Anatomy of mediastinum and its disorders


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Anatomy of mediastinum and its disorders

  1. 1. ANATOMY OF MEDIASTINUM AND ITS DISORDERS<br />Dr.G.GIREESH,<br />P.G Resident<br />Dept.Of Gen.Medicine.<br />
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  3. 3. ANATOMY OF MEDIASTINUM<br />It is the anatomic space that lies in the midthorax <br />Separates the two pleural cavities.<br />It is limited by the diaphragm below and the suprasternal thoracic outlet above.<br /> It contains several vital structures in a small space,<br />Abnormalities can produce important symptoms. <br />For clinical purposes, Divided into <br />Anterior, <br />Middle, <br />Posterior compartments <br />
  4. 4. ANATOMY OF MEDIASTINUM<br />The Anterior compartment contains <br />The Thymus,<br />Substernal extensions of the thyroid <br />Parathyroid glands, <br />blood vessels<br />Pericardium<br />Lymph nodes<br />
  5. 5. ANATOMY OF MEDIASTINUM<br />The middle compartment contains the <br />Heart,<br /> Great vessels,<br />Trachea, <br />Main bronchi,<br /> Lymph nodes, <br />Phrenic and <br />Vagus nerves. <br />
  6. 6. ANATOMY OF MEDIASTINUM<br /> The posterior compartment<br />The vertebrae <br />Descending aorta, <br />Oesophagus,<br />Thoracic duct, <br />Azygous and Hemizygous veins <br />Lower portion of the vagus,<br />Sympathetic chains, and<br />Posterior mediastinal nodes.<br />
  7. 7. Disorders of superior mediastinum <br />Enlarged lymph nodes due to <br /> Tuberculosis <br /> Leukemia <br /> Sarcoidosis<br /> Lymphoma <br />Tumors of the thymus <br />Teratomas<br /> Abscesses <br />Intrathoracic thyroid Aneurysm <br />Cystic hygroma<br /> Carcinoma<br /> Vascular tumours <br />Oesophageal lesions<br />
  8. 8. DISORDERS OF ANT.MEDIASTINUM<br /> These include<br />Lymphoma <br />Lymph node enlargement due to <br /> Tuberculosis<br /> Hodgkin’s disease <br /> Sarcoidosis<br />Thymus tumours <br />Diaphragmatic hernia<br />Thyroid aneurysm<br />Parathyroid aneurysm <br />
  9. 9. LYMPHOMAS<br />These arise in the anterior Mediastinum<br />Hodgkin's lymphoma is the most frequent <br />Carries the best prognosis. <br />Other malignancies with worst prognosis are <br /> Non-Hodgkin's lymphoma<br /> Plasmacytomas <br /> Angiomatous lymphoid hamartomas <br />
  10. 10. Thymus masses<br />The thymus gland is relatively large at birth.<br /> After puberty, it regresses to a small size. <br />A Thymic mass can be a Tumour <br /> Cysts <br /> Thymic lymphoma <br />Cysts may be single or multiple. <br />Usually asymptomatic <br />They manifest on chest X-ray as an enlarged thymus.<br />
  11. 11. Thymus masses<br />Thymoma is a common mediastinal tumour. <br />It is usually malignant <br />Usually associated with myasthenia gravis. <br /> Some are asymptomatic.<br /> Enlarging tumours present with features of mediastinal compression syndrome <br />Chest x-ray -Rounded shadow in the Ant. Mediastinum.<br /> Lateral view gives better delineation of the tumour.<br /> Surgical resection is the best method of treatment.<br />
  12. 12. THYROID MASSES<br />Retrosternal extension of an enlarged thyroid <br />Majority are multinodular benign goitres <br />Cystic areas with hemorrhage and calcification. <br />X-ray-show a sharply defined and often lobulated outline. <br /> Rarely symptomatic<br />Compress the trachea at the thoracic inlet and result in respiratory distress <br />Occasionally cause superior vena cava syndrome.<br />Thyroid cancer involves the mediastinum by <br /> Direct extension <br /> Metastases to <br /> nodes. <br />
  13. 13. TERATOMAS<br />Identical to certain testicular and ovarian neoplasms,<br /> Arise from primitive germ cells <br />Arise by migrating to the mediastinum during oncogenesis.<br />Dermoid cysts contain disorganized mixture of all 3 layers. <br />i.e. skin, hair, cartilage, bone, epithelium, and neural tissue. <br />They often contain cystic areas.<br />Should be excised To prevent further expansion<br />To exclude malignant change<br />
  14. 14. TERATOMAS<br /> .<br />Malignant germ cell tumours are classically divided into <br /> 1) Seminomas.<br /> 2) Teratomas. <br /> Non-seminomatous germ cell tumours (malignant teratoma) can range from well-differentiated to trophoblastic. <br /> Serum levels of α-FP and β-HCG are ↑sed<br /> Seminomas tend to be non-secretory. <br />These tumours are very malignant and invade adjacent mediastinal structures.<br /> Not cured by surgery<br />These are responsive to chemotherapy using cisplatin-based regimes.<br />
  15. 15. PERCARDIAL CYSTS<br /> Occur in the anterior compartment and cardiophrenic angle<br /> They contain clear liquid and a flattened endothelial or mesothelial lining with a bland fibrous wall.<br /> Develop embryologically in relationship to the pericardium,<br /> Rarely communicate with the pericardial sacs <br /> X-ray-Smooth, clear, demarcated densities <br />D/D’S-Pericardial fat pad<br /> Hernia through the foramen of Morgagni.<br /> Aspiration reveals clear fluid.<br /> Surgical excision is not recommended.<br />
  16. 16. Middle mediastinum<br />Aortic aneurysm<br />Pericardial cyst <br />Bronchogenic cyst <br />Lipoma<br />Lymphoma<br />Neoplasm<br />Morgagni’s hernia<br />
  17. 17. BRONCHOGENIC CYSTS<br />Arise in association with the major airways <br />Dvp. around the paratracheal area or carina <br />Middle and posterior compartments<br />Lined by respiratory epithelium. <br />Contain inspissated mucus.<br />Cough or wheezing due to local pressure on airways<br />Occasionally they communicate with the trachea<br />There is an increased tendency to recurrent infections.<br /> Symptomatic pt.s need surgical removals of the cysts<br />
  18. 18. MEDIASTINAL LYMPHADENOPATHY<br />Middle mediastinum is the commonest site of intrathoracic lymphadenopathy.<br />Gross lymphadenopathy is a feature of<br /> 1)Tuberculosis<br /> 2)Histoplasmosis. <br /> 3) Metastatic carcinoma<br /> 4) Lymphomas, <br /> 5)Sarcoidosis.<br />
  19. 19. Giant follicular lymph node hyperplasia (Castleman's disease)<br /> Its Aetiology is unknown. <br />The lesion consists of a vascular tumour with satellite lymphadenopathy.<br />Two histological subgroups are described, <br />(1) a more common hyaline vascular picture with lymphoid follicles and penetrating capillaries <br />(2) a plasma cell type characterized by sheets of plasma cells between germinal centres.<br /> It causes pressure effects <br />Systemic symptoms with fever, anaemia, and weight loss.<br />Small group of patients with multicentric disease have progressive hyperplasia, recurrent infections, and subsequently develop a frank lymphoma.<br />
  20. 20. Posterior mediastinum<br />Esophageal lesions<br />Neurogenic tumours<br />Cysts<br />Diaphragmatic hernia<br />Aortic Aneurysm<br />Meningocoele<br />Parasitic cysts<br />
  21. 21. BOCHDALEK HERNIA<br />
  22. 22. Enteric cysts<br />Are located in the posterior mediastinum <br />Lined by gastric or intestinal epithelium. <br />All cysts may become1) Infected<br /> 2) Bleed<br /> 3)Rupture <br />Rupture into the Mediastinum. <br /> Pleural cavity.<br />
  23. 23. Tumours of post.mediastinum<br />Found in the paravertebral gutters,<br />Neural in origin. <br />Benign tumours tend to be asymptomatic, <br />Malignant tumours cause pressure effects. <br />Occasionally, spinal cord compression results from direct extension into the intravertebral foramen.<br />Tumours arising from peripheral nerve cell sheaths include Neurilemmoma (Schwannoma) <br />Neurofibroma<br /> Malignant counterparts. <br />Tumours of the autonomic chain include Ganglioneuroma<br />Neuroblastoma.<br />
  24. 24. NEUROGENIC TUMOURS<br />There are 4 histological types.<br />1.neurilemmoma<br /> Benign and is classically a dumbbell-shaped mass. <br /> compress the spinal cord and produce pressure symptoms.<br /> 2.ganglioneuroma<br /> Benign, elongated and large. <br /> Usually occurs in children but may be found at any age.<br /> Causes flushing,hypertension,headache,sweating,diarrhoea.<br />3.neurofibroma<br /> Associated with generalized neurofibromatosis<br /> (von Recklinghausen's disease).<br /> 4.NEUROBLASTOMA<br /> Malignant and found frequently in children.<br />
  25. 25. AORTIC ANEURYSMS<br />causes :<br />Hypertension<br />Atherosclerosis<br />Blunt chest trauma<br />Mycotic dissection<br />Cystic medial necrosis in Marfans syndrome<br />Ehlers- Danlos syndrome<br />Aortitis in tertiary syphilis<br />Coarctation of aorta <br />
  26. 26. VASCULAR TUMORS<br />Vascular tumors may originate in the mediastinum.<br /> Vascular hamartomas<br />Lymphangiomas and <br />Hemangiomas are benign tumors.<br />Hemangiopericytomas are malignant. <br />Mesenchymal benign -lipoma<br />Malignant-Liposarcoma<br />Mesothelioma<br />Rhabdomyosarcoma<br />Mesenchymoma<br />These rarely cause mediastinal masses.<br />
  27. 27. PNEUMOMEDIASTINUM<br />There are 3 possible causes -<br /> 1) penetrating chest wall injuries; <br /> 2) tear or defect in trachea, bronchus or oesophagus;<br /> 3) tear or defect in alveolar wall<br /> Air from alveoli enters the interstitial space, <br />Travels along the perivascular sheath into the mediastinum <br />Enters the subcutaneous tissues of the neck and chest wall<br />Results in surgical emphysema.<br />Pt. gets sudden pain in the substernal areas and dyspnoea.<br /> X-ray –Air accumulation parallel to the heart and aorta. <br />In surgical emphysema-subcutaneous crepitations are felt .<br />Treatment of the underlying disorder is necessary. <br />Rarely needs surgical incision.<br />
  28. 28. MEDIASTINITIS<br />It usually results from <br /> Oesophageal rupture<br /> Bronchial rupture<br />Tuberculous lymphadenitis. <br /> Infection from subphrenic abscess <br />Osteomyelitis of spine. <br />Treatment-<br /> 1.Appropriate Antibiotics. <br /> 2.Surgery.<br />
  29. 29. CHRONIC FIBRINOUS MEDIASTINITIS<br />Its a chronic slowly progressive fibrosis. <br />Similar to idiopathic retroperitoneal fibrosis.<br /> Various theories have been put forward but not proven. <br />Involves S.V.C, Azygos and Innominate veins. <br />Apart from engorged neck veins, swelling of face and neck, one may get headache, breathlessness, giddiness and epistaxis. <br />X-ray chest-Widening of the upper mediastinum. <br />Secondary causes of mediastinal fibrosis like tuberculosis and histoplasmosis must be ruled out.<br /> Corticosteroids can be tried.<br /> Surgical removal of fibrotic bands relieves the symptoms.<br />
  30. 30. Superior Vena Cava Syndrome <br />Obstruction of blood flow through the superior vena cava causes dilation of the collateral veins of the upper thorax and neck and edema and congestion of the face<br /> patients may have headache, dyspnea, dysphagia, and wheezes. Malignancy is the most frequent cause of this syndrome,<br /> bronchogenic carcinoma <br /> lymphoma a distant second.<br />Fibrosingmediastinitis<br />Methysergide ingestion. <br />Aortic aneurysm <br />Retrosternal thyroid <br />Invasive procedures are contraindicated.<br /> When the obstruction is thought to be caused by tumor, effort must be made to obtain tissue elsewhere. <br />Irradiation, chemotherapy, or stent placement should be initiated before attempts are made to obtain mediastinal tissue. <br />
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  32. 32. Organ involvedSymptoms and signs<br />1. Trachea, main bronchi -Stridor, dyspnoea, cough, features of lung collapse <br />2. Oesophagus- Dysphagia (extrinsic compression on barium swallow)<br /> 3. Superior vena cava -Engorged non-pulsatile neck veins, oedema and cyanosis of face, neck and arms<br /> 4. Left recurrent laryngeal nerve- Hoarseness of voice, bovine cough<br /> 5. Phrenic nerve- Hemi-diaphragm paralysis <br />6. Sympathetic trunk- Horner’s syndrome<br />
  33. 33. Diagnostic approach<br />1.chest x-ray<br />2. Computed tomography (CT) –<br />3. Magnetic resonance imaging-For spinal tumours.<br />4.Fine-needle aspiration biopsy – valuable .<br />5. Anterior mediastinotomy.<br />6. Bronchoscopy –limited value<br />
  34. 34. THANK YOU<br />
  35. 35. Thymoma<br /> <br />General Considerations<br />Most common anterior mediastinal mass<br />Accounts for 50% of anterior mediastinal masses and 25% of all mediastinal tumors<br />Most are solid lymphoepithelial tumors of the thymus, some are cystic<br />About 1/3 are malignant under 20 and over 40 years of age<br />About half are malignant in those 20-40<br />Rare in children — most common around 5th or 6th decade<br />Mean age of 52<br />They can be classified into four types which occur in about equal frequency<br />Lymphocytic<br />Epithelial<br />Mixed<br />Spindle cell (Hassall’s corpuscles in this type)<br />There are World Health Organization classifications and surgical staging classifications as well<br />Clinical Findings<br />Most benign thymomas are asymptomatic<br />Most with malignant thymomas are symptomatic<br />Symptoms include<br />Cough<br />Chest pain<br />Dyspnea<br />Dysphagia<br />Superior vena caval syndrome<br />Red cell aplasia, hypogammaglobulinemia or collagen vascular disease such as dermatomyositisand lupus<br />Imaging Findings<br />Conventional radiographs of the chest may show <br />Oval round or lobulated soft tissue mass, sharply demarcated, usually smaller than teratomas<br />Superior aspect of anterior mediastinum<br />Project predominantly to one side or the other<br />May displace heart and great vessels posteriorly<br />On CT <br />
  36. 36. Normal thymic tissue may be seen as a triangular density in the anterior mediastinum up to 30 years of age at which time fatty involution occurs<br />Thymus should be < 1.8 cm up to 20 years and < 1 cm after 20 years<br />A small percentage (5%) may contain curvilinear or amorphous calcification<br />Absence of fat planes and invasion of adjacent structures favors malignancy<br />A homogeneously enhancing capsule favors benignancy<br />MRI<br />May be more sensitive to small thymic masses than CT<br />Hypointense to mediastinal fat on T1<br />On T2, signal is isointense or hyperintense ro surrounding fat<br />Differential Diagnosis<br />Non-Hodgkin’s lymphoma can occur in thymus<br />Thymolipomas are rare, fatty tumors of the thymus that have been associated with<br />Aplastic anemia<br />Hypogammaglobulinemia<br />Grave’s disease<br />Hodgkin’s disease<br />Chronic lymphocytic leukemia<br />Anterior Mediastinal Masses – 3 T’s and an L<br />Thymoma <br />Teratoma <br />Thyroid enlargement <br />Lymphoma <br />Treatment<br />Most thymomas are treated surgically<br />Degree of invasiveness rather than histopathology is best determinant of malignancy versus benignancy<br />Complications<br />About 15% of patients with myasthenia gravis have thymomas and about 33-50% of patients with thymomas have myasthenia<br />Thymomas are associated with leukemia<br />Prognosis<br />Surgical evaluation of encapsulation or invasion is better indicator of prognosis than actual histology<br />In patients with myasthenia, about 50% improve following removal of the thymoma<br />For those with invasive thymoma, 15 year survival is 12.5%<br />For those with non-invasive thymoma, 15 year survival is 47%<br />