CANCER (NEOPLASM)

Table of contents : 


  • Epidemiology
  • Aetiology
  • Pathogenesis
  • Metastases
  • Oncogenomics
  • Morphology 
  • Symptoms & signs
  • Oncological emergencies
  • Laboratory examinations
  • Experimental animal models
  • Prevention
  • Therapy 
  • Prognosis
  • Spontaneous tumour regression
  • Specific organ cancers 
  • Web resources
  • Bibliography

  • Cell types in children : ovary (45%), sacrococcygeal region (40%, causing dystocia), testes, retroperitoneum, mediastinum (=>respiratory distress) , nasopharynx, intracranium, neck and stomach(monodermoma : a tumor that has developed from one germ layer)
    benign tumor
    malignant tumor
    epithelial cells
    Laboratory examinations : IHC with epithelial markers (cytokeratins 1, 5, 10, 14; EGFR, b2-microglobulin) 
  • adenoma : a benign epithelial tumor in which the cells form recognizable glandular structures or in which the cells are clearly derived from glandular epithelium
    • adenoma alveolare : an adenoma whose cells are arranged like those of an alveolar gland. 
    • mucinous adenoma : an epithelial tumor whose cells produce mucin. 
    • embryonal or trabecular adenoma : a follicular adenoma whose cells are closely packed to form cords or trabeculae, with only a few small follicles 
    • tubular adenoma : an adenoma whose cells are arranged in tubules, as occurs with adenomatous polyps of the colon, some fibroadenomas of the breast, and androblastoma. 
  • papilloma / papillary tumor / villoma / villous papilloma or tumor : a benign epithelial neoplasm producing finger-like or verrucous projections from the epithelial surface
  • polyp : a morbid excrescence, or protruding growth, from mucous membrane; classically applied to a growth on the mucous membrane of the nose, the term is now applied to such protrusions from any mucous membrane.

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    carcinoma : a malignant new growth made up of epithelial cells tending to infiltrate the surrounding tissues and give rise to metastases
    • adenoid cystic, adenocystic or cribriform carcinoma / cylindroma : carcinoma characterized by bands or cylinders of hyalinized or mucinous stroma separating or surrounded by nests or cords of small epithelial cells. It appears as one or more of 3 patterns:
      • cribriform carcinoma
      • solid carcinoma
      • tubular carcinoma
      Malignant and invasive but slow growing, it spreads by infiltrating the bloodstream and perineural spaces 
    • adnexal carcinoma : carcinoma forming structures resembling the cutaneous appendages, particularly the sweat or sebaceous glands.
    • basosquamous or metatypical cell carcinoma : carcinoma that histologically exhibits both basal and squamous elements.
    • cancer or carcinoma in situ / preinvasive carcinoma : a neoplastic entity wherein the tumor cells are confined to the epithelium of origin, without invasion of the basement membrane; the likelihood of subsequent invasive growth is presumed to be high
    • carcinoma medullare, molle or spongiosum / medullary carcinoma / cerebriform, encephaloid, medullary, or soft cancer or carcinoma : carcinoma composed mainly of epithelial elements with little or no stroma; sites where this is commonly found are the breast and thyroid gland
    • scirrhous cancer or carcinoma / scirrhoma / fibrocarcinoma / carcinoma fibrosum : carcinoma with a hard structure owing to the formation of dense connective tissue in the stroma
    • metaplastic carcinoma
    • adenosquamous carcinoma : areas of glandular, squamous, and large-cell differentiation
    • sarcomatoid carcinoma (SC) / pseudosarcoma : sarcomatoid transformation of a carcinoma histologically resembling a sarcoma. Current terminological preferences are such that several formerly used terms--including "spindle-cell carcinoma," "pulmonary blastoma," "squamous cell carcinoma with pseudosarcomatous stroma," "pseudosarcoma," and "carcinosarcoma"--are now encompassed by the more generic designation of "sarcomatoid carcinoma."
      • polymorphic sarcoma type : sarcomatoid components are polymorphic
      • spindle cell type : sarcomatoid components consisted of spindle cells
      • osteoclastic giant cell type : a huge number of osteoclastic giant cells in the sarcomatoid components
      • myxocartilage type : myxocartilaginoid components are seen in the tumor tissue
    • spindle cell carcinoma / monophasic sarcomatoid carcinoma : carcinoma, usually of the squamous cell type, marked by fusiform development of rapidly proliferating cells
    • villous carcinoma / carcinoma villosum : carcinoma in which the cells are arranged in a villous pattern, as papillary projections which are covered with neoplastic epithelium; usually seen in the gastrointestinal tract
    • epidermoid, prickle, planocellular or squamous cell carcinoma (SCC) : carcinoma developed from squamous epithelium, having cuboid cells and characterized by keratinization and often by preservation of intercellular bridges. Initially local and superficial, the lesion may later invade and metastasize
    • adenocarcinoma : carcinoma derived from glandular tissue or in which the tumor cells form recognizable glandular structures; adenocarcinomas may be classified according to the predominant pattern of cell arrangement
      • acinar, acinous or acinic cell carcinoma, adenocarcinoma or tumor : a slow-growing malignant tumor characterized by acinic cells arranged in small glandlike structures, usually occurring in the pancreas or salivary glands, particularly in females
      • adenoacanthoma : an adenocarcinoma in which some or the majority of the cells exhibit squamous differentiation
      • alveolar adenocarcinoma
      • papillary or polypoid adenocarcinoma / dendritic cancer : an adenocarcinoma in which the tumor elements are arranged as finger-like processes or as a solid spherical nodule projecting from an epithelial surface
      • tubular carcinoma or cancer : an adenocarcinoma in which the cells are arranged in the form of tubules
      ... or according to a particular product of the cells, as mucinous adenocarcinoma 
      • colloid, gelatinous, mucinous, muciparous, or mucous cancer, carcinoma or adenocarcinoma / carcinoma mucosum or muciparum : an adenocarcinoma that produces mucin in significant amounts
        • signet-ring cell carcinoma or adenocarcinoma : signet-ring cell (one in which the nucleus has been pressed to one side by an accumulation of intracytoplasmic mucin)
      • serous adenocarcinoma
      • clear cell adenocarcinoma or carcinoma / mesonephroma : a rare malignant tumor of the female genital tract, resembling a renal cell carcinoma and containing tubules or small cysts with some cells that are hobnail-shaped and others whose cytoplasm is clear, containing abundant glycogen (hence "clear" during staining after fixation for microscopy) and inconspicuous stroma. It arises from multipotent serous mullerian cells and may occur in the ovary, uterus, cervix, vagina, and bladder

      • Aetiology : one form has been linked to in utero exposure to diethylstilbestrol (DES)
    mesenchymal cells => connective-tissue tumor : any tumor developed from some structure of the connective tissue bone tissue
  • chondroma
    • osteolipochondroma : a benign cartilaginous tumor containing osseous and fatty elements
  • osteoma
  • sarcoma : any of a group of tumors usually arising from connective tissue, although the term now includes some of epithelial origin; most are malignant
  • chondrosarcoma
  • osteosarcoma
  • fatty tissue lipoma
    • osteolipoma : lipoma with osseous metaplasia
    • topholipoma : a lipoma containing tophi
    soft tissue sarcoma (STS) : a general unnatural term used by clinicians and for convenience by pathologists for a malignant sarcoma derived from extraskeletal connective tissue (as opposed to those of the soft epithelial tissues), with almost all lesions originating from primitive mesoderm. Not included are the reticuloendothelial system, glia and supporting tissues liposarcoma (12-33%)
    fibrous tissue fibroma / fibroid tumor : a tumor composed mainly of fibrous or fully developed connective tissue 
    • cystic fibroma : a fibroma that has undergone cystic degeneration.
      • hard fibroma / fibrum durum : one composed of fibrous tissue with few cells
    fibrosarcoma (6-40%) : a malignant tumor composed of cells and fibers derived from fibroblasts, which produce collagen but otherwise lack cellular differentiation; it is grossly grayish white and firm, invades locally, and metastasizes hematogenously. Several varieties occur: an aggressive adult form, a rarely metastasizing infantile or congenital form, an inflammatory form, and a postirradiation form. 
    • osteogenic fibrosarcoma : from anaplastic fibroblasts in any area of osseous metaplasia. Cells contain microcrystals of hydroxyapatite seen at TEM
    myocytoma : a tumor made up of myocytes
    • smooth muscle tissue
    • rough muscle tissue
    leiomyoma
    rhabdomyoma
  • leiomyosarcoma (2-11%)
  • rhabdomyosarcoma (3-20% in adults; 50% in childhood)
  • peripheral nervous system (PNS) glioma neurofibrosarcoma (5-7%) 
    gliosarcoma
    vascular tissue angioma  angiosarcoma (3%)  mesenchymal perivascular epithelioid cell tumours (so-called PEComas) : coexpression of melanocytic (HMB-45) and muscle (MyoD1) markers 
    histiocytes
    malignant fibrohistiocytoma (20%)
    synovial tissue
    synovial sarcoma (4-10%)

    uncertain origin
    2-5%
  • epithelioid sarcoma : a rare, frequently metastatic tumor consisting of lobulated masses of spindle and epithelioid cells surrounding a necrotic center; it usually arises in the deep soft tissues of the distal extremities in young adults, particularly males.
  • alveolar soft part sarcoma : a well-circumscribed, slow growing, painless, highly metastatic malignant neoplasm of unknown cell origin, characterized by a distinctive alveolar pattern and occurring predominantly in the extremities (thigh) of adult females, or head (orbit) and neck of children. On the contrary of most sarcomas, it also causes hematogenous metastases to lung, brain, bones, and arterovenous fistulae. Cytoplasm is rich of mitochondria and SER, lipid vacuoli, and rod-like crystalline structures surrounded by membranes
  • spindle cell sarcoma : a type of soft tissue sarcoma whose cells are spindle-shaped; it is usually resistant to radiation therapy and may be of either high or low grade malignancy.
  • telangiectatic sarcoma : a sarcoma that develops a rich vascular network; the endothelial cells may be mistaken for the neoplastic element.
  • embryoma / embryonal tumor : any neoplasm thought to be derived from embryonic cells or tissues, such as a dermoid cyst, teratoma, primitive neuroectodermal tumor, embryonal carcinoma or sarcoma, nephroblastoma, or hepatoblastoma
  • germ cell tumors (GCT) : any of a group of tumors arising from primitive germ cells (PGCs), usually of the testis or ovary. Oct-3/4 is almost exclusively in GCTs and the level of expression is related to the immaturity—and hence the malignancy—of the tumor. Types include :
    • benign GCTs :
      • mature or benign cystic teratoma / dermoid cyst / teratoblastoma / dysembryoma / organoid or teratoid tumor (80-90% of al teratomas) : teratoma of the testis, usually found in young women, presumably derived from the ectodermal differentiation of totipotential cells, lined by apparent skin and its associated adnexal structures, and typically filled with a sebaceous caseous material in which is found hair
        • didermoma / bidermoma : a teratoma composed of cells and tissues derived from 2 cell layers
        • tridermoma : a teratoma containing representatives of all 3 germ layers.
        • sequestration cyst : collection of cancerous cells which form cysts that contain one or more of the 3 primary embryonic germ layers: skin, hair or teeth. 
        Epidemiology : 1 every 40,000 newborns; female-to-male ratio 3:1
        Localizations
        • in children : ovary (45%), sacrococcygeal region (40%, causing dystocia), testes, retroperitoneum, mediastinum (=>respiratory distress) , nasopharynx, intracranium, neck and stomach
        • in adults : in the ovary or testis
        Therapy : surgical resection
      • gonadoblastoma : rare, it contains all gonadal elements, including germ cells, sex cord derivatives, and stromal derivatives and is frequently associated with an abnormal chromosomal karyotype. It may give rise to development of a dysgerminoma or other more malignant GCT.

      • Localizations : usually arising in dysgenetic gonads (ovary or testis), often bilaterally
    • malignant GCTs :
      • yolk sac tumor (YST) or carcinoma / endodermal sinus tumor (EST) / adenocarcinoma of infantile testis / infantile or juvenile embryonal carcinoma : a malignant GCT of children 1-5 years old that represents a proliferation of both yolk sac endoderm and extraembryonic mesenchyme (43-9F mAb+). YST is characterized by numerous patterns including labyrinthine glandular (similar to rat placenta with Schiller-Duval bodiesand myxoid stroma), myxomatous, sarcomatoid, hepatoid, and parietal variants.It is characterized by a glandular pattern; frequently there are intracytoplasmic or extracytoplasmic eosinophilic, PAS+ round hyaline bodies or globules. IHC for cytokeratins and AFP
        • pure YST
        • part of a mixed germ cell tumor
        Localizations : it most often occurs in the testis (orchioblastoma), but is also seen in the ovary and some extragonadal sites (prostate, sacrococcygeal region, pericardium, pineal gland, urachus, liver, uterus
        Therapy : cisplatin-based chemotherapy alone is an alternative to laminectomy or radiation therapy in the management of epidural cord compression from EST, even when the cord compression is severe. 
      • immature, malignant or solid teratoma (IT) / teratoblastoma / dysembryoma / organoid or teratoid tumor : a solid tumor resembling a dermoid cyst but composed of immature embryonal and/or extraembryonal elements derived from all 3 germ layers

      • Symptoms & signs : growing teratoma syndrome (GTS)
        Localizations
        • in children : ovary (45%), sacrococcygeal region (40%, causing dystocia; Middeldorpf or tailgut tumor : Middeldorpf V. Zur Kenntnis der Angebornen Sacral-Geschwulste. Virchows Arch (Pathol.Anat.) 101:37-41 (1885). This term is no longer used becauseit lacks specificity), testes, retroperitoneum, mediastinum (=>respiratory distress) , nasopharynx, intracranium, neck and stomach
        • in adults : in the ovary or testis
        Laboratory examinations : tumor markers : AFP+ref in epithelial cells of primitive cysts, adenoid and gut-like structures of probably entodermal origin; b-hCG
        Therapy : surgery followed by vincristine + chemotherapy (AMD, cyclophosphamide, methotrexate, bleomycin)
      • teratoma with malignant transformation (MT) is a well-described entity that refers to the MT of a somatic teratomatous component in a GCT to a histology that is identical to a somatic malignancy (carcinoma or sarcoma, eg, primitive neuroectodermal tumors, undifferentiated rhabdomyosarcoma, anaplastic small-cell tumor, adenocarcinoma, and leukemia)

      • Therapy : surgical resection has been the mainstay of therapy for localized transformed disease because these tumors are thought to be resistant to standard treatment. Chemotherapy for MT limited to a single cell type may result in major responses and long-term survival in selected patients. Local therapy after chemotherapy is an important component of treatment to achieve maximum response. 
      • spermatocytic seminoma (SS) / spermatocytoma (10%) : clean background, low mitotic rate, areas (10-30% of the tumor) in which the 3 cell types characteristic of conventional spermatocytic seminoma can be identified under light microscopy, absence of lymphocytes, low tendency to metastasize, diploid or polyploid > aneuploid, c-kit+/- (derived from spermatogonia or primary spermatocytes but 40% of the SSs originate from primordial cells), PLAP-, NY-ESO-1+
        • spermatocytic seminoma associated with a sarcomatous component, sometimes rhabdomyosarcomatous type : the presence of the sarcomatous elements transformed the usually innocuous spermatocytic seminoma into a highly aggressive neoplasm. The sarcomatous elements may represent a nonseminomatous germ cell component
      • germinoma / gonocytomas (gonocyte is the primitive reproductive cell of the embryo or a secondary gamete-producing cell) : a type of GCT consisting of large round cells with vesicular nuclei, usually found in the ovary, undescended testis, anterior mediastinum, or pineal gland. All are characterized by isochromosome 12p : the (dysplastic) gonocytes from which these tumours are derived are prone to polyploidization, especially in the gonads
        • seminoma / spermatocytoma / spermocytoma / seminomatous germ cell tumor : a radiosensitive, malignant neoplasm of the testis, a type of GCT thought to be derived from the sexually undifferentiated embryonic gonad; they retain their gonocyte characteristics and the single gonocytes have little or no stem cell potential.; 3 histologic variants are recognized
          • testicular carcinoma in situ (CIS) / intra-tubular germ cell of neoplasia of the unclassified type => testicular seminomas; problematic variants include seminomas with tubular, granulomatous, and edematous patterns. 
            • classical seminoma (CS) / typical seminoma (TS) / classic pure seminoma (85%) : "tigroid" background, stromal lymphoid infiltrates, retroperitoneal relapse, aneuploid, c-kit+, PLAP+, NY-ESO-1-
            • anaplastic seminoma (AS) (5%) : spermatocytic seminoma with a predominant anaplastic component (nuclei have large rope-like nucleoli with granular and filamentous chromatin). In addition, sheets of cells with vesicular nuclei and prominent nucleoli superficially resembling embryonal carcinoma are found. There are numerous large mononuclear and multinucleated giant cells with bizarre nuclei and prominent nucleoli, but no sarcomatous elements. Many normal and abnormal mitotic figures are present. Tunical and vascular invasion and extensive necrosis are constant features. IHC : p53 overexpression, PLAP-, LCA-, NSE-, AFP-, hCG-, vimentin-, and cytokeratins-. Despite the presence of a major anaplastic component, no patient has developed metastasis.
          • seminoma with syncytiotrophoblastic giant cells (STGC) secretes hCG (a fact that raises serious difficulties in its differential diagnosis with combined seminomas and choriocarcinomas)
          • atypical seminoma
          • teratogenic gonocytoma if the tumour stem cell has differentiation potential; it is an epiblastoma (epiblast is the upper layer of the bilaminar embryonic disc present during the second week; it gives rise to ectoderm except for the neural plate) if no differentiation is manifest, but may differentiate along embryonic lines into teratoma or may show extraembryonic differentiation towards yolk sac tumor or choriocarcinoma
        • dysgerminoma : the most common malignant GCT of the ovary, composed of large round or polygonal cells with much glycogen, which are frequently radiosensitive and located bilaterally

        • Aetiology : mutations in OPCML
      • embryonal carcinoma (EC) : a highly malignant GCT that is a primitive form of carcinoma, probably of primitive embryonal cell derivation; it has a histological appearance similar to that of a yolk sac tumor (43-9F mAb+; PLAP+ in 75% ), producing a-fetoprotein (AFP) in the cytoplasm of single cells in the solid masses and in areas forming tubular patternsref. In females, there is a median age of 15; in males the majority of patients are adolescents or older. It usually occur admixed with other GCT types. The combination of positivity for placental alkaline phosphatase and negativity for epithelial membrane antigen can assist in the distinction of embryonal carcinomas from somatic carcinomas.
        • pure EC
        • part of a mixed germ cell tumor
      • some types of choriocarcinoma
    • combined or mixed GCTs : AFP+ structures could be interpreted as early stages of embryonal developmentref
    • polyembryoma : a rare, immature GCT characterized by numerous AFP+refembryoid bodies in association with mature and immature teratoma structures (extraembryonic differentiation) and primitive embryonic tissue, usually found in the ovary => retroperitoneum) and testis. AFP+ not only in yolk sac cells among the embryoid bodies, in the endoderm and in the margins of the ectodermal cells, but also in multiple elements in the mucinous matrix. Hepatoid tissues react positively to AFP and alpha antitrypsin (AAT) as well as to hCG. By using hCG and human placental lactogen (hPL) as markers it is proven that among trophoblastic cells of the tumor, not only syncytiotrophoblastic cells but also the intermediate cells and the cytotrophoblastic cells could be identifiedref.
    Many tumors are mixtures of types. 
    Growing teratoma syndrome consists of an enlarging mature teratoma arising during or after chemotherapy for a nonseminomatous germ-cell tumor, with normal serum levels of alpha-fetoprotein and human chorionic gonadotropin ()Logothetis CJ, Samuels ML, Trindade A, Johnson DE. The growing teratoma syndrome. Cancer 1982;50:1629-1635). The preferred treatment is complete surgical resection2 because teratomas are resistant to chemotherapy and radiation therapy. Although embryonal carcinomas express little or no retinoblastoma protein (pRB),3 mature teratomas express high levels of pRB. Normally, cyclin-dependent kinase 4/6 (CDK4/6) stimulates cell growth by phosphorylating pRB. The development of selective CDK inhibitors,ref including PD0332991 (Pfizer), which selectively inhibits CDK4/6, suggests a new treatment for growing teratoma syndromeref
    embryoid bodies : structures resembling embryos, occurring in several types of GCTs. 
    Hepatic tissue is observed in 9.3% of GCTs. The incidence of hepatic tissue is low in tumors of the ovary (5%), high in both retroperitoneal (27%) and sacro-coccygeal (24%) tumors, and low in both mature (0.3%) and immature teratomas (11%). It is usually encountered in infancy, and the frequency is high in both yolk sac tumors (48%) and mixed GCTs (52%). The hepatic tissue found mainly in mature or immature grade 1 teratomas was similar to adult normal human liver tissue (Ha-type). Tissue in areas consisting of some immature somatic elements of a mixed GCT is similar to embryonic or fetal liver tissue (Hf-type). Many hepatic nests found in a polyembryoma are of both Ha- and Hf-types. The hepatic tissue found in close relation to yolk sac elements shows predominantly hepatocellular carcinoma-like features (HCLS). Immunohistochemically, the cytoplasm of adult liver-type cells is positive for a1-antitrypsin (AAT), human albumin (ALB), and the third (C3) and fourth (C4) components of the complement system. The cytoplasm of fetal liver-type cells shows the same positivity; in addition, these cells are positive for a-fetoprotein (AFP) in 25% of the cases. The cytoplasm of hepatic cells of HCLS was positive for AFP, AAT, ALB, C3, and C4. A weakly positive reaction for CEA and CA19-9 is observed in bile duct-like structure in some Hf-type casesref.
  • melanocytoma : a neoplasm or hamartoma composed of melanocytes
  • (malignant) melanoma (MM) / melanotic cancer or carcinoma / melanoblastoma / melanocarcinoma (1.5%) : a malignant neoplasm of melanocytes, characterized by irregular borders and dyshomogeneous color (also achromic areas) and cytological atypias

  • Epidemiology : > 100,000 new cases of melanoma are diagnosed every year and the numbers are rising; 30,000 deaths every year worldwide 
    Pathological types
    • superficial spreading melanoma (SMM) : the most common type of MM, characterized by a period of radial growth atypical of melanocytes in all layers of the epidermis (Paget's cell / pagetoid cell (a large, irregularly shaped, pale anaplastic tumor cell with vacuolated cytoplasm and a vesicular nucleus that is usually hyperchromatic and surrounded by a clear zone; cells occur singly or in small clusters in the epidermis)) which do not undergo neurotization, usually associated with regional lymphadenitis and a lymphocytic cellular host response that is sometimes accompanied by partial or complete regression of the radial growth phase (RGP); deeply invasive growth (vertical growth phase (VGP)) is superimposed on the radial phase. It occurs most often on the lower leg or back, usually presenting as a small pigmented macule to a slightly palpable flat lesion that assumes an irregular outline on enlargement. While RGP melanoma cells remain dependent on exogenous growth factors supplied by surrounding keratinocytes, are incapable of anchorage-independent growth, are not tumorigenic in immmunodeficient mice and do not metastatize in patients, VGP melanoma cells acquire growth-factor and anchorage-independent growth, are tumorigenic in animals and are highly metastatic both in patients and in experimental animal models.
      • Allen-Spitz melanoma : juvenile melanoma, a poorly pigmented lesion composed of plump spindle and/or epitheloid cells, some perhaps multinucleated with large nuclei, often with prominent nucleoli and mitosis. Is now considered malignant melanoma, type superficial spreading (Allen A & Spitz S. Compound blue nevi. Cancer 6:1-6 (1953))
    • nodular melanoma : a type of MM arising without a perceptible radial growth phase, most often occurring on the head, neck, and trunk, typically presenting as a uniformly pigmented, elevated, bizarrely colored nodule that enlarges rather rapidly and commonly ulcerates, which may arise de novo or from a preexisting malignant melanoma of a different type.
    • acral-lentiginous melanoma: an uncommon type of MM, although it is the most common type seen in nonwhite individuals, occurring chiefly
      • on the palms and soles, especially on the distal phalanges of the fingers and toes, often on the tip of the digit or nail fold or bed (subungueal melanoma)
      • sometimes involving mucosal surfaces, such as the vulva or vagina
      It typically presents as an irregular, enlarging black macule, which has a prolonged noninvasive stage.
    Histology :
    • conventional MM
    • polypoid MM
    • desmoplastic MM (DMM)
    Configuration of tumor cells :
    • mixed cell type
    • epitheloid cell type
    • spindle cell type
    Clarke's classification
    • I : many melanosomes of different sizes, melanofilaments
    • II : nuclear anomalies, abortive spheroidal melanosomes
      • type 1 : pigmented melanocytes
      • type 2 : nonpigmented melanocytes (amelanotic melanoma : an unpigmented MM)
    • III : only spherical melanosomes (commonest type)
      • granular matrix, partially melanotic
      • lamellar
    • IV : granular or lamellar organelles, many mitochondria
    Onset
    • sporadic melanomas (90%) :
      • 0.2-2% have germline mutations in CDKN2A. Some have somatic mutations that exclusively affect the ARF-coding sequence in the shared exon 2 or ARF-specific exon 1b deletion
      • activating Tyr-HRAS mutations
      • absence or very low incidence of point mutation or allelic loss of TP53
      • Myc amplification and overexpression
      • activating NRAS mutations in 56% of congenital nevi, 33% of primary melanomas and 26% of metastatic melanoma, rarely in dysplastic nevi, suggesting a distinct evolutionary path to melanoma
    • familial melanomas (10%) :
      • 25-40% have inactivating mutations in CDKN2A (it contains 2 upstream exons, 1a and 1b, driven by separate promoters, which result in alternative transcripts that share common downstream exons 2 and 3 : although a common acceptor site in the second exon is used by both first exons, the ORFs remain distinct in the shared exon 2) : some specifically target exon 1a which codes for INK4A / p16 exclusively (it inhibits CDK4/CDK6-mediated phosphorylation and inactivation of RB1), others p14 / ARF (it inhibits MDM2-mediated ubiquitylation and subsequent degradation of p53). On the contrary INK4B inactivation is not significant : as INK4A is lost in almost all established melanoma cell lines, but in only 15-28% of primary uncultured sporadic melanoma samples, one possible cancer-relevant distinction between INK4A and INK4B might relate to the capacity of INK4A to regulate cellular senescence. 95% of these also have activating NRASmutations, compared with only 10% of those with no family history. The lifetime penetrance (by age 80 years) is 67% overall, but only 58% in Europe, compared with 91% in Australia and 76% in USA, paralleling the baseline population incidences of melanoma for these regions, which is influenced by the amount of UV-light exposure.
      • CDK4 Arg24Cys or Arg24His mutations are epistatic to INK4A inactivation
      • multiple benign or dysplastic nevi (moles)
      • red hair colour (RHC) phenotype : red hair, a fair complexion, the inability to tan and a tendency to freckle, associated with MC1R Arg151Cys, Arg160Trp and Asp294His variatns, which increase the amount of pheomelanin in skin => diminished UV-light protective capacity, increased production of mutagenic and cytotoxic metabolites, and additional pigmentary-independet effect(s) on melanoma risk. The presence of a single MC1R variant increases the penetrance of CDKN2A mutation from 50% to 84%.
      • HGF / SF-HGF-R activation stimulates proliferation and motility of melanocytes by disrupting adhesion between melanocytes and keratinocytes via downregulation of E-cadherin and desmoglein-1 ("scattering").
      • 10q LOH (30-50%) :
        • PTEN (in 5-15% of uncultured melanoma specimens and metastases, as well as in 30-40% of established melanoma cell lines)
        • the MYC antagonist MXI1
      • mutations in BRAF (60% of melanomas, activating V599E mutation (also present in 82% of nevi) in 80% of cases)
      • MITF (20%) : up to 13 copies
    Tumour-associated antigens
    Pathogenesis : the expression pattern of Slug, a master regulator of neural crest cell specification and migration, correlates with those of other genes that are important for neural crest cell migrations during development. Moreover, Slug is required for the metastasis of the transformed melanoma cells. These findings indicate that melanocyte-specific factors present before neoplastic transformation can have a pivotal role in governing melanoma progressionref
    Metastases : cancer cells express high levels of CXCR4 (up-regulated thanks to positive selection exercted by hypoxia on tumour cell clones lacking inhibition of the VHL tumour suppressor over HIF-1a), CCR7, and CCR10, and are characterized by a distinct metastatic pattern involving the regional lymph nodes, skin, bone marrow, lung and liver, ie tissues that express peak levels of the ligand chemokines CXCL12 and CCL21 : signalling through CXCR4 or CCR7 mediates actin polymerization and pseudopodia formation, and subsequently induces chemotactic and invasive responses. Rarely intratracheal metastasesref
    Localizations
    • cutaneous melanoma (CM) (99%)
    • mucosal melanoma (MuMs) (1%) : on a mucous membrane (50% are mucosal melanomas of the head and neck (MMHN), accounting for approximately 0.2% of all melanomas), usually in older women; most are acral-lentiginous, but nodular and superficial spreading melanomas also occur

    • Epidemiology : incidence is 0.4 cases per million in USA Epidemiology : equal gender distribution and with a peak incidence in the age range 60-80 years. In consequence of their hidden location, they are usually diagnosed in a locoregionally advanced clinical stage, with a rate of 5-48% of regional and 4-14% of distant dissemination. 
      Prognosis : far more aggressive behaviour than that of skin melanomas; 5-year actual survival rates are poor (17-48%), which is attributed mainly to a haematogenous dissemination 
      Therapy : earlier reports advocated radical surgery as the mainstay of therapy; however, local recurrence and survival were unchanged whether radical surgery or local excision was performed, and the most recent data are favoring the conservative approach when appropriate. Unfortunately, a multitude of adjuvant therapies have been tried without any success. Adjuvant radiotherapy plays a role when combined with surgery, particularly in the head and neck region and female genitalia, but this is reserved for nodal and locoregionally advanced disease and has had no effect when used as a prophylactic method. Local control with either surgery or radiotherapy is frequently (60-70%) achieved, but the rates of local, regional and distant recurrences are high (50-90%, 20-60% and 30-70%, respectively). 
    • melanomatosis : the formation of melanomas in various parts of the body.
    Laboratory examinations :
    • IHC for S-100 protein, tyrosinase, HMB-45, melan A, and microphthalmia transcription factor
    • cancer thickness : thicker melanomas are more likely to spread than thinner ones, but thin cancers sometimes spread too, and only 40% of thick melanomas spread
      • Breslow's thickness : maximal thickness of a primary cutaneous melanoma measured in tissue sections from the top of the epidermal granular layer, or from the ulcer base (if the tumour is ulcerated), to the bottom of the tumour, as assessed with micrometric oculars; metastatic rates correlate closely with tumour thicknessref.
      • Clark's level or thickness (Clark WH. A classification of malignant melanoma in man correlated with histogenesis and biological behaviour. Adv.Biol.Skin 8:621-647 (1967)) : the level of invasion of primary malignant melanoma of the skin. The prognosis is worse with each successive deeper level of invasion.
        • I : limited to the epidermis
        • II : into the underlying papillary dermis (< 0.76 mm)
        • III : to the junction of the papillary and reticular dermis (0.76-1.5 mm)
        • IV : into the reticular dermis (1.5-4 mm)
        • V : into the subcutaneous fat (> 4 mm)
    • lymphatic density (LD) and lymphatic invasion ref :
      • > 12 lymph vessels / mm2 => secondary tumours
      • < 5 lymph vessels / mm2 => cancer does not spread
    • sentinel-node biopsy and subsequent immediate lymphadenectomy do not confer an overall survival benefit for patients with melanoma. Although this procedure has a proven prognostic value, the long-term benefits of adjuvant therapy for patients with melanoma who are identified by means of this procedure are uncertainref. In addition, the cost-effectiveness of the procedureref calls into question the proposed "standard-of-care" designation. The staging of intermediate-thickness (1.2 to 3.5 mm) primary melanomas according to the results of sentinel-node biopsy provides important prognostic information and identifies patients with nodal metastases whose survival can be prolonged by immediate lymphadenectomyref
    Therapy :
    • chemotherapy :
      • thalidomide in combination with low dose temozolomide has generated favorable results in a phase II investigation as an oral regimen for patients with advanced-stage metastatic melanoma whose disease has not metastasized to their brains
      • MEK inhibitor trametinib + BRAF inhibitor dabrafenib
    • augmerosen combined with dacarbazine raises the median survival time to 9.1 months from 7.9 months for patients treated with dacarbazine alone. For patients treated per protocol, who had completed a minimum follow-up time of 12 months, Genasense resulted in a median survival of 10.1 months, compared with 8.1 months for dacarbazine alone.
    • BRAF inhibitors
    • immunotherapy :
      • immunostimulant antibodies (ipilimumab + nivolumab)
      • IL-2 : high numbers of tumour-associated CD64+ macrophages in tumour biopsies were statistically significantly associated with poor response to treatmentref
      • high-dose adjuvant intravenous IFN-a2b for all patients with intermediate- and high-risk melanoma after resection : the substantial toxicity of the therapy and the fact that its benefit is limited to 20-30% of patients at risk have hindered its general acceptance. During treatment the median relapse-free survival was 16.0 months among patients without autoimmunity (antithyroid, antinuclear, anti-DNA, and anticardiolipin autoantibodies, and patients were examined for vitiligo) (108 of 148 had a relapse) and was not reached among patients with autoimmunity (7 of 52 had a relapse). The median survival was 37.6 months among patients without autoimmunity (80 of 148 died) and was not reached among patients with autoimmunity (2 of 52 died). In univariate and multivariate regression analyses, autoimmunity was an independent prognostic marker for improved relapse-free survival and overall survival (P<0.001)ref. Because autoimmunity was observed only after a median of three months — and in some instances, more than a year — from the start of IFN-a2b therapy, the development of autoimmunity cannot be used as a criterion for selecting patients for the therapyref. Nonetheless, patients with a documented preexisting propensity toward autoimmunity might be a group for whom immunotherapy should be considered, providing that the resulting autoimmunity could be anticipated to be managed effectivelyeref
      • therapeutic cancer vaccines :
    Prognosis : only 35-50% of people with stage III melanoma and 5-10% of those with stage IV disease will achieve long-term survival
    Web resources
  • mesothelioma : a tumor derived from mesothelial tissue (mesothelin+)
    • benign or localized fibrous mesothelioma (10%)
    • malignant mesotheliomas (often the result of excessive exposure to asbestos)

    • Epidemiology : about 880 people die of mesothelioma each year throughout Japan
      Histological subtypes (WHO classification) : 
      • epithelial subtype (55%) : better prognosis when early diagnosed and treated with intrapleural immunotherapy or multimodality therapy
        • tubulopapillary subtype = low-grade mesotheliomas
        • epithelioid subtype = high-grade mesotheliomas
          • malignant mesothelioma with deciduoid features (MMWDF) : MNF116+, HBME-1+, and calretinin+
      • biphasic subtype (30%)
      • sarcomatoid subtype (15%)
      Localizations Aetiology
      • environmental carcinogens (asbestos (80% in the Western World : only a relatively small fraction of those exposed develop malignant mesothelioma) and erionite) : the risk is 9.5 times higher than the national average among people who lived within 500 meters of a now-defunct Kubota Corp. asbestos plant in Amagasaki, Hyogo Prefecture, Japan, and 4.7 times higher than the national average among residents living between 500 meters and 1 km from the plant.
      • viruses (SV40, a DNA tumor virus that preferentially causes mesothelioma in hamsters, has been detected in several human mesotheliomas. The expression of the SV40 T antigen in mesothelioma cells, and not in nearby stromal cells, and the capacity of antisense T-antigen treatment to arrest mesothelioma cell growth in vitro suggest that SV40 contributes to tumor development. The capacity of T-antigen to bind and inhibit cellular p53 and Rb-family proteins in mesothelioma, together with the very high susceptibility of human mesothelial cells to SV40-mediated transformation in vitro, supports a causative role of SV40 in the pathogenesis of mesothelioma. Asbestos appears to increase SV40-mediated transformation of human mesothelial cells in vitro)
      • genetic predisposition (in the villages of Karain and Tuzkoy, in Anatolia, Turkey, 50% of deaths are caused by mesothelioma. Erionite may be a cofactor in these same villages)
      • exposure to ionizing radiations (minor importance)
      Pathogenesis : p53 mutations are rarely found in mesothelioma; p16, p14ARF, and NF2 mutations/losses are frequent 
      Treatment : historically, no classes or combinations of agents consistently yielded response rates > 20%. 
      • surgical ablation (most are not candidates)
      • radiotherapy (alone didn't demonstrate any efficacy on the patient survival; most are not candidates)
      • chemotherapy alone didn't demonstrate any efficacy on the patient survival
      • stage I :  a therapeutic approach seems to be neoadjuvant intracavitary treatment using cytokines
      • stages II and III : multimodality protocol combining surgery, radiotherapy and chemotherapy (doxorubicin=> P30 and pemetrexed) has proved to be effective in patients with epithelial subtype, negative margins of resection and negative lymph nodes.
    • germinal epithelial tumors
    • angiomatoid tumour : a small, circumscribed, benign tumour of the genital tract, composed of small glandlike spaces lined by flattened or cuboidal mesothelium-like cells.
    Between first symptoms of disease and diagnosis of mesothelioma often more than 6 months pass as clinical symptoms are rarely typical 
    Laboratory examinations
    • histopathological distinction between adenocarcinoma and mesothelioma requires TEM and experienced pathologists.
    • tumor markers : CA-125
  • primitive neuroectodermal tumor (PNET) : proposed name for a heterogeneous group of neoplasms thought to derive from undifferentiated neuroglial cells of the neural crest
  • They occur as : 
    • central PNETs : brain, spinal cord and sympathetic nervous system
    • peripheral PNETs (pPNETs) : epidural spinal, extremities, the pelvis, or the chest wall, seen most often in adolescents and young adults, frequently with widespread metastases
      • Askin's tumor : a malignant small-cell tumor of soft tissue in the thoracopulmonary region in childrenref
      • Ewing's sarcoma family of tumors (ESFT)
      • melanotic neuroectodermal tumor (MNET) of infancy (MNTI) / melanotic progonoma or ameloblastoma / melanoameloblastoma / pigmented ameloblastoma / retinal anlage tumor : a rare benign but locally aggressive, rapidly growing, deeply pigmented tumor consisting of an infiltrating mass of cells arranged in an alveolar pattern. Its source of origin is in dispute, the various theories giving rise to its several names. Maturation of the neural elements (e.g. to ganglionic elements) has been reported only occasionally.

      • Epidemiology : occurring almost exclusively in infants during the first year of life 
        Localizations
        • jaw MNTI (mostly)
          • upper jaw MNTI
            • anterior hard palate
          • lower jaw MNTI
        • epididymal MNTI
        • soft tissues of the arm
        • skull
        • central nervous system MNTI (male/female ratio 3.5; much worse outcome. The average age is 8 years (range 3.5 months to 69 years) with 85% becoming clinically apparent in the first decade of life; 73.7% of the patients reported succumbed to their disease at a mean age of 2.8 years, with a postoperative survival time of just 9 months. Systemic metastases were reported in 9 cases and had mostly spread via cerebrospinal fluid)
        Therapy : conservative excision
    Tumor markers : NSE
    Experimental animal models : canine malignant melanoma (CMM) is an aggressive neoplasm that is initially treated with surgery and/or radiation therapy.  Unfortunately, the median survival time (MST) for stage II-III CMM treated with surgery alone is 3-5 months.  Hypofractionated RT and chemotherapy in > 90% stage I CMM results in a MST of only 1 year
  • neuroendocrine tumours (NT)
  • carcinoid (tumor) / apudoma : a yellow circumscribed tumor (0.5-1 cm) arising from APUD cells
    • low-grade typical carcinoids (TC)
    • intermediate-grade atypical carcinoids (AC)
    Epidemiology : incidence varies between 0.8 and 1.9/100,000 population. 
    Localizations Symptoms & signs :
    • asymptomatic (66%)
    • carcinoid syndrome (if from argentaffinoma it is a.k.a. argentaffinoma syndrome) due to excess serotonin levels
    • Rarely carcinoid syndrome develops in patients with noncarcinoid malignant tumors and dermatomyositis
    Prognosis : 5-year survival varying between 15% and 35% 
    • about 20% present with metastases
      • multiple liver metastases don't worse survival rates, but in some cases heterotopic incretion increases the likelihood to develop carcinoid syndrome as liver catabolism (serotonin is metabolized in the liver by MAO into 5-hydroxyindole acetic acid (5-HIAA)) is bypassed
      • most osseous metastases have been reported from carcinoids of the stomach or rectum
    • the development of second primary malignancies (SPM) in patients with gastrointestinal carcinoid tumors is a well-described phenomenon, with reported rates as high as 55%. There is a predilection for gastrointestinal and genitourinary adenocarcinomas, but a variety of other malignancies have been reported as well. The etiology of this malignant predisposition may be rooted in the tumorigenic properties of the various neuroendocrine peptides elaborated and secreted by neuroendocrine cells. Peptides such as secretin, gastrin, bombesin, cholecystokinin (CCK), and vasoactive intestinal peptide (VIP) are believed to promote the growth of tumor cells. As many as 30 peptides and amines identified in neuroendocrine cells may have similar properties. 
    Laboratory examinations
    • biopsy =>
      • histology : firm, gray-yellow, submucosal nodules. They grow through the muscularis mucosa and the bowel wall into the mesentery. Mesenteric invasion provokes an intense fibrotic reaction. If the tumors become large, they may present as intraluminal polypoid masses, and occasionally, they are ulcerated.
        • alveolar or glandular carcinoid : palisade of cells at periphery of nidi, no atypias
        • trabecular or nastriform or gyriform carcinoid : cells arranged in cords
        Intracytoplasmatic vesicles and vacuoles (resisting to fixation) 100-700 nm with peripheral pale halo, increased volume of RER and SER. 
      • IHC with panneuroendrocine tumor markers (NSE, synaptotagmin, neurophysin, NCAM, keratins AE1 and AE3) and hormones (not all carcinoids secrete hormones)
    • preoperative ultrasound may show a solid, hypoechoic, well-defined margin mass combined with calcification or a cyst.
    • [5-HT, histamine]plasma and [5-hydroxy-indolacetic acid (5-HIAA)]urine.
    • chest X-ray, chest, abdominal and pelvic CT, and octreotide scintigraphy are indicated for assessing metastases (even umbilical metastases)
    Therapy
    • surgical resection is the only curative option
    • surgery can also offer prolonged palliation and is needed to restore bowel transit in obstructive/ischaemic bowel problems
    • adequate palliation of hormone-related symptoms can also be achieved by
    • TACE of liver metastases (response rate = 50%, but is accompanied by significant side effects)
    Prognosis : median survival = 3.5-8..5 years; unfavorable prognostic factors are glandular or mixed histological type, size > 2 cm, location in anterior intestine, [5-HIAA]urine > 150 mg/die 

    high-grade neuroendocrine tumours (HGNT)

    • large cell neuroendocrine carcinomas (LCNECs)
    • small cell carcinomas (SCCs)
      • oat-cell type carcinoma : the cells are round or elongated and slightly larger than lymphocytes; they have scanty cytoplasm and clump poorly.
      • intermediate cell type
      • combined cell type carcinoma
      Localizations
      • small cell lung carcinoma (SCLC)
      • extrapulmonary small cell carcinoma : pure or mixed with squamous-cell carcinoma
        • genitourinary tract
          • epididymis
          • prostate
          • breast (12 cases reported in worldwide literature)
          • uterine cervix
          • endometrium 
          • kidney (30 cases reported in worldwide literature)
          • bladder (135 cases reported in worldwide literature)
        • parotid
        • esophagus
        • stomach 
        • duodenum 
        • pancreas
        • liver
        • gallbladder
        • colon 
        • larynx 
        • primary left ventricular tumor
        • unknown primary tumor 
        Therapy : curative surgery or primary combination chemotherapy consisting of etoposide and cisplatin + local-regional adjuvant radiotherapy 
        Prognosis : median survival for patients with limited disease was 25 months compared to 12 months for patients with extensive disease 
  • small round blue cell tumors (SRBCT) of childhood are a group of tumors that share a common histologic characteristic with H&E staining :  they all appear small, blue (high nuclear-to-cytoplasmic (N/C) ratio with nucleus which stains with hematoxylin) and round, but they are vastly different from each other
    • small cell carcinomas
    • non-Hodgkin's lymphoma (NHL)
    • undifferentiated sarcoma
    • small cell osteosarcomas
    • extraskeletal myxoid chondrosarcomas
    • mesenchymal chondrosarcoma
    • Ewing's sarcoma
    • rhabdomyosarcoma (RMS)
    • malignant rhabdoid tumour (MRT) resembles rhabdomyosarcoma but the tumour cells are very primitive rather than of myogenic origin

    • Epidemiology : found almost exclusively in infants (occasionally diagnosed at or immediately after birth) 
      Localizations
      • primarily in the kidney (malignant rhabdoid tumur of the kidney (MRTK))
      • it may be found in other parts of the body
        • childhood atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system (CNS). Most AT/RTs demonstrate monosomy 22 or deletions of chromosome band 22q11 with alterations of the hSNF5/INI1 gene. The tumor's incidence is still undefined, but it may comprise as high as 1 in 4 primitive CNS tumors in infants. Treatment (surgery, chemotherapy, and radiotherapy) is far from optimal, but there are occasional long-term survivors, especially among older children
        • sites outside of the kidney and CNS (21 cases congenital MRTs have been published in the literature. 18 patients had disseminated disease at diagnosis. The median overall survival time for all patients was 2.0 months (0-24 months). The only patient who survived had a localized tumor at initial diagnosis
          • chest wall, axilla, right elbow, and bone marrow. Chest wall lesion was resected completely. Although the masses in axilla and bone marrow responded rapidly to chemotherapy, the elbow lesion increased in size
      Laboratory examinations : distinctive light microscopy and immunohistochemical findings 
      Prognosis : poor (highly lethal) 
    • Merkel cell carcinoma (MCC)
    • nephroblastoma / Wilms' tumor
    • medulloblastoma
    • hepatoblastoma
    • neuroblastoma
    • carcinoid tumors
    • malignant peripheral PNET (pPNET) or peripheral neuroepithelioma
    • desmoplastic small round cell tumor (DSRCT) is an increasingly recognized, high-grade malignant tumor that has a predilection for adolescent males. These polyphenotypic tumors characteristically, but not invariably, arise in intimate association with the serosal membrane of the peritoneal cavity and harbor a signature translocation : t(11;22)(p13,q12). In the paratestis they often involve the surface of the epididymis. Characteristic cytologic features include granular chromatin, smooth to irregular nuclear membranes, nuclear molding, cytoplasmic vacuoles, cytoplasmic densities, pseudorosettes, and metachromatic stroma
    mixed tumors : a tumor composed of more than one type of neoplastic tissue adenoepithelioma : a tumor composed of glandular and epithelial elements.
    mucoepidermoid carcinoma : a malignant epithelial tumor of glandular tissue characterized by acini with mucus-producing cells and by the presence of malignant squamous elements; it may occur as a low, intermediate, or high grade malignancy


    carcinosarcoma / biphasic sarcomatoid carcinoma : a malignant tumor composed of carcinomatous and sarcomatous tissues, a differentiation continuum of spindle-cell carcinomas / monophasic sarcomatoid carcinoma
    mesenchymoma : a mixed mesenchymal tumor composed of 2 or more cellular elements not commonly associated, not counting fibrous tissue as one of the elements. benign mesenchymoma
    • rhabdomyochondroma : striated muscle and cartilaginous elements.
    • rhabdomyomyxoma : striated muscle cell and myxoid elements
    • chondromyoma : myomatous and cartilaginous elements.
    • lipomyohemangioma / angiomyolipoma (AML) : by a mixture of spindle (muscle))cells, adipose tissue, epithelioid cells, and blood vessels

    • Localizations
    • lipomyoma / myolipoma : fatty and muscle elements
    malignant mesenchymoma / mixed cell sarcoma : a sarcoma composed of 2 or more cellular elements (excluding fibrous tissue) 
    • myxoid chondrosarcoma / chondromyxosarcoma : myxoid and cartilaginous elements

    myxoma / colloid, gelatinous or mucous tumor : a benign tumor composed of primitive connective tissue cells and stroma resembling mesenchyme 
    • cystic myxoma / myxocystoma : myxoma with cystic degeneration
    • enchondromatous myxoma : one containing cartilage in the intercellular substance.
    • myxoma fibrosum / myxofibroma : a fibroma containing myxomatous tissue.
    • lipomatous myxoma / lipomyxoma / myxolipoma / lipoma myxomatodes : lipoma with foci of myxomatous degeneration.
    • myxoma sarcomatosum / myxosarcoma : a sarcoma containing myxomatous tissue.
    • vascular myxoma : a myxoma containing many blood vessels
    • angiomyxoma : a chorioangioma containing capillary-like blood vessels; it may extend into the umbilical cord and often contains myxomatous tissue resembling that in the normal cord.

    • Localizations : cutaneous angiomyxoma
  • fibroelastoma : a neoplasm consisting of fibroelastic elements.

  • Localizations : papillary fibroelastoma

    collision tumor : an area of mixing of malignant cells from 2 distinct tumors (such as a carcinoma and a sarcoma) that have developed separately but near each other.
    desmoid tumor : a fibromatous tumor arising in the musculoaponeurotic tissue, usually of the abdominal wall, and often closely resembling low-grade fibrosarcoma; desmoid tumors are not encapsulated, are locally invasive, and rarely metastasize. The tumor often infiltrates adjacent muscle and has a high incidence of recurrence despite seemingly adequate gross resection. The highest frequency is in women of childbearing age of which over 90% of tumors are abdominal in location. For abdominal wall desmoid tumors, approximately 33% are associated with a previous operation at the tumor site
    Symptoms & signs : the most frequent presenting symptom is a nontender, palpable abdominal wall mass
    Laboratory examinations : diagnostic imaging is best carried out by CT or MRI, which delineate the extent of involvement of the layers of the abdominal wall and potential intraperitoneal extension
    Therapy : initial treatment of abdominal wall desmoid tumors is surgical. Because the margins of the tumor are not easily determined and because the tumor often infiltrates muscle and periosteum, limited margins around the gross tumor frequently result in microscopic tumor at the margin. Recurrence rates for abdominal desmoid tumors vary from 9% to 40%, and recurrence is frequent with inadequate margins. A 5-cm margin of resection is considered adequate with mono bloc resection of rib cage, pubic or iliac bone or involved portions of organs such as bladder to achieve these margins. Reconstruction of the abdominal wall with polypropylene mesh is necessary in most cases. In patients in whom adequate margins of resection are achieved, there is no benefit from adjuvant radiotherapy. Second and third resections after recurrence have been associated with no higher rate of recurrence than primary resection. Radiotherapy alone has achieved local control in desmoid tumor in as many as 100% of tumors treated primarily and 75% of recurrent tumors. Radiation doses at least 60 Gy are considered necessary for consistent control. The large radiation dose risks major damage to adjacent bowel and therefore primary radiation treatment of abdominal wall desmoid tumors has a limited role. 
    Sarcomas :

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