HOMO SAPIENS DISEASES : MEDIASTINUM

• thoracic fistula : an abnormal passage communicating with the thoracic cavity.
• tracheal fistula : an abnormal passage communicating with the trachea.
• tracheocutaneous fistula : an abnormal connection between the trachea and the surface of the neck, due to epithelialization of a tracheotomy opening.
• bronchocavitary fistula : a fistula connecting a bronchus and a cavity within the lung.
• bronchopleural fistula : a fistula between a bronchus and the pleural cavity, sometimes seen after lung surgery or as a complication of empyema, fibrosis, or pneumonia.
• pulmonary fistula : an abnormal passage communicating with the lung.
• mediastinitis : inflammation of the mediastinum.
• acute mediastinitis : an often fatal inflammation of the mediastinum

Aetiology :
• usually secondary to perforation of the esophagus by
• forceful vomiting
• trauma
• spontaneous (Boorheave syndrome)
• less often it may be caused by spread of an infectious process from some adjacent organ or area
• descending necrotizing mediastinitis (DNM) is a rare but serious complication of otopharyngeal (e.g. peritonsillar abscess) and deep neck infection that spreads down to the mediastinum through the cervical-facial planes

Aetiology : b-hemolytic Streptococcus spp. (>90%)
Therapy : aggressive surgical drainage and appropriate antibiotics and hyperbaric oxygen therapy (HBOT) might be of great value as an adjunctive management to control this fatal infection^ref
Prognosis : mortality rate remains high
Pathogenesis : there may be obstruction of structures in the area, such as the superior vena cava or the tracheobronchial tree
Symptoms & signs : sudden onset of chills, fever, and prostration, severe chest pain and sometimes tachypnea, sinusal tachycardia, pneumomediastinum, and hemomediastinum
• chronic mediastinitis : any of numerous inflammatory conditions of the mediastinum

Aetiology : often secondary to a fungal or tuberculous infection;
Symptoms & signs : may be minimal or the result of obstruction of structures in the area. The most common specific condition is :
• fibrosing, fibrous or indurative mediastinitis (FM) / mediastinal fibrosis : development of whitish, hard fibrous tissue in the upper mediastinum, causing compression, distortion, or obliteration of the superior vena cava, and sometimes constriction of the bronchi and large pulmonary vessels. Patients of fibrosing mediastinitis are usually young. Fibrosing mediastinitis can be either idiopathic (arising spontaneously) or from an abnormal immunologic response to Ajellomyces capsulatum
• granulomatous mediastinitis : mediastinal fibrosis with granulomas.
Web resources : TransGlobal Health Community Center support group for people affected by "Fibrosing Mediastinitis
• mediastinic lymphadenitis
• diseases of thymus
• thymic aplasia : absence of the thymus gland, as in DiGeorge's syndrome
• Dubois' thymic abscess or disease : abscess of the thymus in congenital syphilis
• thymic tumors : tumors of the thymus
• thymic epithelial tumours (TET) : thymic epithelial cell (TEC) neoplasm (27% : 4% are purely epithelial tumors)

Marino, Muller-Hermelink, and Kirchner (MMHK) morphologic classification of thymomas based on the resemblance of the neoplastic cells to subtypes of the normal thymic epithelial cells
• thymomas / organotypic thymic epithelial tumours (TET) : a tumor derived from the epithelial or lymphoid elements of the thymus (95% in anterior mediastine, 5% in neck, left hilum or intraparenchymal; 30-60% invade capsula (malignant thymoma), 3-5% give metastases)
• benign
• medullary thymoma
• predominantly epithelial and spindle cell
• mixed type thymoma
• thymoma with pseudosarcomatous stroma is a recently described, rare variant of thymomas that are characterized by having a biphasic histologic pattern which consists of both an epithelial and a spindle cell stromal component. So far only 12 cases having similar histologic findings have been reported worldwide.
• low-grade
• organoid thymoma (predominantly cortical)
• cortical thymoma
• low-grade metaplastic carcinoma of the thymus
• well differentiated thymic carcinoma (WDTC) / non-organotypic thymic epithelial tumours (TET) / squamous cell carcinoma (SCC)
• high grade thymic carcinomas / non-organotypic thymic epithelial tumours (TET)
• poorly differentiated
• moderately differentiated
• lymphoepithelioma-like carcinoma
• micronodular thymoma with lymphoid B-cell hyperplasia : the aetiological relationship of EBV with these tumours could not be proved. The lymphoid B-cell hyperplasia may result from a host immune response and may suggest a favourable clinical course of this type of tumour.
• ectopic thymomas
• primary intrapulmonary thymoma is a rare lesion with around 20 cases reported so far in the literature. A pure spindle cell morphology in these lesions is rarer still with only 2 cases recorded to date.
• ectopic hamartomatous thymoma (EHT) is a rare benign tumor that consists of
• nests of epithelial cells, including solid, cystic, or glandular epithelial islands
• spindle cells (cytokeratin⁺EMA⁺) dominating the microscopic picture. The transition from spindle epithelial cell to myoid cell (cytokeratin⁺EMA⁺myoglobin⁺creatine kinase-mm⁺) has been reported
• adipose cells which intermingle haphazardly to impart a hamartomatous quality to the tumor
It may develop from the third branchial pouch or thymic anlage.
• thyroidal epithelial thymomas are a rare group of thyroid neoplasm tumors.
• spindle epithelial tumor with thymus-like differentiation (SETTLE) of the thyroid has been reported only 17 times in English literature
• pericardial rhabdomyomatous spindle cell thymoma with mucinous cystic degeneration
• spindle cell thymoma (1-5%) : associated to immunodeficiency
• composite tumor of organoid thymoma (WHO type B1) and lipofibroadenoma
WHO classification, 1999 :
• thymomas
• medullary and mixed thymomas
• type A
• type AB
• type B : predominantly cortical and cortical thymomas and well-differentiated thymic carcinomas
• type B1
• type B2
• type B3
• type C / thymic carcinoma
Radiologically, a smooth contour and round shape are most suggestive of a type-A tumor, whereas an irregular contour most strongly suggests type C. The findings of computed tomography (CT) imaging revealed that type A and AB tumors tend to be round and have the smooth surface while type B1, B2 and B3 tumors are often flat and have irregular surface. Pleural seeding is rare in type-A and AB tumors; calcification is suggestive of type B. Type-C tumors are significantly larger and more commonly associated with lymphadenopathy than type B3. At T2-weighted MR imaging, lobular internal architecture is more prominent in types B1, B2, and B3 tumors than in others. However, imaging findings among the various types overlap to some extent, and the ability of imaging studies to differentiate types AB, B1, B2, and B3 is limited. Type AB, B1 and B2 tumors possess a significant number of CD4⁺CD8⁺ double positive T cells in the tumor.
Aetiology :
• myasthenia gravis is associated in 0%, 6.8%, 40.0%, 55.6%, 10.0%, and 0% in patients with type A, AB, B1, B2, B3, and C tumors, respectively
• the histologic type of thymomas associated with pure red cell aplasia (PRCA) has generally been regarded to be predominantly the spindle cell type, but recent studies has shown that lacks a strong correlation with a particular histologic type and the pathogenesis of PRCA associated with thymoma did not seem to be related to the histologic type.
• hypogammaglobulinemia with thymoma (Good's syndrome)
Masaoka clinicopathological classification :
• stage I
• stage II
• stage III
• stage IVa
• stage IVb
Rosai-Levine staging :
• type I (noninvasive, rare atypias and mitoses => ablative surgery)
• type II (invasive => chemotherapy, radiotherapy)
• IIA : locally invasive
• IIB : metastases
• T lymphocyte lymphomas (22%)
• mixed neoplasm (50%)
• connective tissue neoplasm
• teratoma
• neuroendocrine neoplasms
• thymic carcinoid
• small cell neoplasm
Thymus-related syndromes :
• neuromuscular syndromes
• myasthenia gravis (30%)
• Lambert-Eaton myasthenic syndrome (LEMS)
• myositis
• dermatomyositis
• hematological syndromes
• pure red cell aplasia (PRCA) (7%)
• erythrocytosis
• pancytopenia
• megakaryocytopenia
• T lymphocytosis
• acute leukemia
• multiple myeloma
• immune deficiencies
• hypogammaglobulinemia
• T lymphocytes deficiency
• connective tissue diseases (CTD)
• systemic lupus erythematosus (SLE)
• rheumatoid arthritis (RA)
• Sjogren syndrome (SS)
• systemic scleroderma
• myocarditis
• polymyositis
• mediastinum neoplasms
• lymphadenopathies
• Hodgkin disease
• non-Hodgkin lymphomas (NHL)
• sarcoidosis
• aspecific or specific infectious lymphopathies
• embrionary neoplasms
• germ cell tumours (GCT)
• immature neoplasms
• embryonic cyst
• mediastinal choriocarcinoma
• mediastinal polyembryoma
• teratoma neoplasms
• transdermal cyst
• mediastinal dermoid cyst
• thymic cysts : rare congenital unilocular or multilocular cysts of the upper anterior mediastinum containing tissue resembling that of the thymus
• bronchial or bronchogenic cyst : a spherical congenital cyst arising from anomalous budding during the formation of the tracheobronchial tree; it is usually found in the mediastinum or the lung and is lined with bronchial epithelium that may contain secretory elements. It may contain air, and if it communicates with the trachea or a bronchus it may periodically evacuate fluid contents into the air passages, resulting in attacks of voluminous expectoration. Infection leads to mediastinal or pulmonary abscess
• enteric or enterogenous cyst / enterocyst / enterocystoma (paraesophageal, at lower third)
• coelomic cyst
• neurenteric cyst : a cyst of the posterior mediastinum containing tissues from the nervous system and other organs, and connecting with the spinal dura mater.
• pericardial cyst : a benign collection of clear fluid, almost always located immediately adjacent to the pericardium; such cysts must be differentiated from the more serious mediastinal tumors.
• thymic tumors
• nervous neoplasms (orthosympathetic ganglia > intercostal nerves > phrenic, vagus, laryngeal)
• neurinoma
• ganglioneurofibroma
• neuroblastoma
• pheochromocytoma
• vascular neoplasms
• lymphangioma
• hemangioma
• connective tissue neoplasms
• fibroma
• fibrosarcoma
• lipomas
• liposarcoma
• endothoracic goitres (thyroid migrates from neck into mediastine)
• prevascular goitre
• retrovascular goitre
• ectopic thyroid (no vascular root)
False tumors :
• aneurysms
• hematomas
• Dubois' thymic abscess or disease
• meningocoele
Localizations :
• anterior / previsceral mediastinum (1 : containing thymus and perithymic adipose tissue)
• upper anterior mediastinum (1a) : goitres, thymic tumors
• intermediate anterior mediastinum (1b) : thymic tumors, lymphomas
• lower anterior mediastinum (1c) : pleuropericardial cysts (at angle between sternum and pleura), thymic tumors
• intermediate / visceral mediastinum (2 : containing heart, ascending aorta, pulmonary artery, and trachea) : benign or malignant lymphatic diseases
• posterior / paravertebral mediastinum (3 : containing esophagus and descending aorta)
• upper posterior mediastinum (3a) : goitres, nervous tumors
• intermediate posterior mediastinum (3b) : nervous tumors, bronchogenous cysts
• lower posterior mediastinum (3c) : nervous tumors, mesenchymal tumors
Symptoms :
• none => accidentalome (50.26 %)
• systemic symptoms (5.70%)
• thoracic pain (8.30%)
• cough / dyspnea (65.5%)
• pulmonary infections (5.7%)
• pleural effusion (3.6%)
• heart disease (2.50%)
• thoracic deformities (2.07%)
• recurrent palsies (1.55%)
• dysphagia (1.55%)
• mediastinum occupation syndrome (2.59%)
• others (1.55%)
Diagnosis :
• posteroanterior and laterolateral chest X-ray
• chest CT
• MRI
• biopsy via mediastinotomy (contraindicated in asymptomatic patients with noninvasive neoplasms due to risk of dissemination)
• pneumomediastinum / Hamman's disease or syndrome / mediastinal emphysema : the presence of air or gas in the mediastinum, which may interfere with respiration and circulation

Aetiology :
• trauma
• pathologic process
• (tracheo)bronchial asthma
• pneumothorax
• interstitial emphysema
• pulmonary barotrauma
• acute mediastinitis
• induced deliberately as a diagnostic procedure
Symptoms & signs :
• Hamman's murmur or sign : a precordial crunching, clicking, or knocking sound, synchronous with each heart beat, heard on auscultation in such conditions as acute mediastinitis, pneumomediastinum, and pneumothorax when patient lies on left side
• subcutaneous emphysema at sternal incisure
Complications : pneumothorax or pneumopericardium
• hemomediastinum : an effusion of blood in the mediastinum.

Aetiology : acute mediastinitis
• mediastinic syndromes
• superior vena cava syndrome
• middle lobe syndrome
• vagus (X) nerve paralysis

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