mediastinum and its surgical anatomy and diseases

mediastinal diseases and management

1. mediastinum

2. Topics anatomy of mediastinum Contents of mediastinum Epidemiology of mediastinal tumors Clinical presentation Radiological anatomy

3. Introduction The mediastinum is the region in the chest between the pleural cavities that contain the heart and other thoracic viscera except the lungs Boundaries Anterior - sternum Posterior - vertebral column and paravertebral fascia Superior -thoracic inlet Inferior - diaphragm Lateral - parietal pleura

4. Sternal Angle Thoracic inlet Thoracic oulet Boundaries of mediastinum sternum Thoracic vertebra

5. TS: Mediastinum 5 CS: Mediastinum

6. Divisions of mediastinum

7. Superior Mediastinum Posterior Mediastinum Anterior Mediastinum Middle Mediastinum Sternal Angle T4 T5 divided into superior mediastinum and inferior mediastinum by an imaginary line passing through sternal angle anteriorly lower border of 4 th thoracic vertebra posteriorly Mediastinum divisions

8. Inferior mediastinum : is subdivided into Anterior mediastinum Middle mediastinum Posterior mediastinum

9. Superior Mediastinum Boundaries Ant: Manubrium sterni Post: T-1 to T-4 Sides: Mediastinal pleura Sup: Plane of thoracic inlet at T1 Inf: Imaginary line joining sternal angle and lower border T-4 9

10. Superior Mediastinum It contains: Trachea Esophagus Blood vessels (large veins & arteries) (listed later) Nerves (listed later) Thoracic duct Thymus Lymph nodes: (listed later)

11. Superior mediastinum contents Blood Vessels Veins: SVC Lt & Rt brachiocephalic veins, Arteries: Arch of Aorta Brachiocepalic artery Lt Common carotid Lt subclavian artery

12. Superior Mediastinum Nerves Vagus nerve Left Recurrent Laryngeal nerve. Phrenic nerve.

13. Superior Mediastinum Lymph nodes: Highest mediastinal Paratracheal Prevascular retrotracheal

14. Anterior Mediastinum Lies ant. to pericardium Boundaries: Anterior: body of sternum Posterior: pericardium superior: imaginary line separating sup. & inf.mediastinum Infreior: diaphragm Lateral: mediastinal pleura

15. Anterior mediastinum: contains: Thymus gland Lymph Nodes Fat.

16. Thymus Located in anterior mediastinum. Develops from endoderm of 3 rd pharyngeal pouch Present in childhood, involutes in adults Blood supply Arterial :i nt. Mammary arteries Venous: internal thoracic veins Lymphatic drainage: lower cervical, int. Mammary and hilar nodes

17. Middle Mediastinum Boundaries: Anterior: posterior surface of sternum Posterior: oesophagus, desc. thoracic aorta, azygous vein Superior: plane seperating sup.& inf mediastinum Inferior: diaphragm Lateral: mediastinal pleura

18. Middle Mediastinum Contents: Heart enclosed in pericardium Arteries: Ascending Aorta, Pulmonary trunk with its Lt & Rt branches Veins : SVC,Pulmonary veins Nerves: Phrenic, vagus nerve Bifurcation of Trachea with two principal bronchi Tracheobronchial lymph nodes 18

19. Posterior Mediastinum Boundaries: Ant. Pericardium, Bifurcation of trachea Post. T5 to T12 sup. Transverse thoracic plane Inf. diaphragm Sides: Mediastinal pleura 19

20. 20 Posterior Mediastinum Contents: Oesophagus Arteries Descending Aorta with its brs Veins Azygos Hemizygos Accessory hemizygos Nerves: Vagus Splanchnic nerves Thoracic duct lymph nodes Posterior mediastinal

21. Trachea: anatomy

22. LENGTH:10-15 cm DIAMETER: 2cm in males &1.5 cm in females Lined by ciliated columnar epithelium Lower level at T6 on inspiration & T4 on expiration Made of c shape rings 2 rings per cm The rings make tube convex anterolateraly Posteriorly the gap is filled by trachealis muscle.

23. NERVE SUPPLY: LYMPHATIC DRAINAGE Pretracheal paratracheal lymph node PARA SYMPHATHETIC: vagus & recurrent laryngeal nerves ( sensory & secreto-motor to mucous membrane motor to trachealis muscle) SYMPHATHETIC: -middle cervical ganglion (vasomotor)

24. Blood supply ARTERIAL SUPPLY Upper trachea Inferior thyroid artery Lower part Branches of the bronchial artery VENOUS DRAINAGE Upper part : left brachiocephalic vein Lower part: Inferior thyroid vein

25. Radiological antomy

26. CHEST X-RAY

27. 27 Tracheobronchial anatomy Tracheal Displacement Due to Goiter

28. Clues to locate mass to mediastinum Mediastinal masses : Masses in the lung not contain air bronchograms mediastinal mass will create obtuse angles with the lung . Mediastinal lines will be disrupted May contain air bronchograms A lung mass abutts the mediastinal surface and creates acute angles with the lung

29. LEFT: A lung mass abutts the mediastinal surface and creates acute angles with the lung. RIGHT: A mediastinal mass will sit under the surface of the mediastinum, creating obtuse angles with the lung

30. Cervicothoracic sign The anterior mediastinum ends at the level of the clavicles. The posterior mediastinum extends much higher. Therefore any mass that remains sharply outlined in the apex of the thorax must be posterior and entirely within the chest, and  any mass that disappears at the clavicles must be anterior and extends into neck

31. See sharp margin above clavicle Mass is in posterior mediastinum. because it remains sharply outlined in apex of thorax, indicating that it is surrounded by lung. This particular example is a ganglioneuroma

32. Thoracoabdominal sign A sharply marginated mediastinal mass seen through the diaphragm must lie entirely within the chest. The posterior costophrenic sulcus extends far more caudally than the anterior aspect of the lung Therefore Any mass that extends below the dome of the diaphragm and remains sharply outlined must be in the posterior compartments and surrounded by lung, and Any mass that terminates at dome of diaphragm must be anterior

33. Can you see the outline of the mass below the diaphragm? Margin of mass is apparent and below diaphragm, therefore this must be in the middle or posterior compartments where it is surrounded by lung This example is a ‘Lipoma ’

34. Hilum overlay sign Principle of hilum overlay An anterior mediastinal mass will overlap the main pulmonary arteries, therefore they will be seen within the margins of the mass

35. Hilum can be seen through mass this must be an anterior mediastinal mass because it overlaps rather than “pushes out” the main pulmonary arteries This particular example is a thymoma

36. VASCULAR ANATOMY

37. At T3 Level

38. At T4 Level

39. At T5 Level

40. At T6 Level

41. MEDIASTINAL TUMORS EPIDEMOLOGY Mediastinal malignancies are heterogenous in nature . most masses (> 60%) are: Thymomas Neurogenic Tumors Benign Cysts Lymphadenopathy (LAD) In children the most common (> 80%) are: Neurogenic tumors Germ cell tumors Foregut cysts In adults the most common are: Lymphomas LAD Thymomas Thyroid masses

42. Mediastinal Masses Compartment % Malignant Anterosuperior 59 Middle 29 Posterior 16 Mediastinal division Most common tumors Anterior-superior thymoma middle lymphoma posterior Neurogenic tumors

43. Anterosuperior Masses Thymus Thymoma Thymic carcinoma Thymic cyst Thymic carcinoid Thymolipoma Mediastinal Lymphoma Hodgkin’s Lymphoma Non-Hodgkin’s Lymphoma Mesenchymal tumors Germ Cell Tumor Seminoma Non seminomatous Germ Cell Embryonal cell carcinoma Endodermal sinus tumor Choriocarcinoma Teratoma Mature Immature Endocrine tumors Thyroid tumors Parathyroid adenoma

44. Middle mediastinal masses Mediastinal Lymphoma Hodgkin’s Lymphoma Non-Hodgkin’s Lymphoma Mesenchymal tumors CYST: Bronchogenic cyst Thoracic duct Meningoceles Cardiac & pericardial tumors Tracheal tumors vascular tumors Lymphadenopathy Inflammatory Granulomatous sarcoidosis

45. Posterior mediastinal masses Mediastinal Lymphoma Hodgkin’s Lymphoma Non-Hodgkin’s Lymphoma Mesenchymal tumors Neurogenic tumors Peripheral nerves Symphathetic ganglia paraganglia ENDOCRINE TUMORS ESOPHAGEAL TUMORS & CYSTS

46. Tumors of thymus Thymomas Thymic carcinomas Thymic lymphomas Carcinoids Thymolipomas Secondaries

47. Thymoma Presentation Most common primary anterior mediastinal tumor M=F, most >40 Most patients are asymptomatic Half of patients suffer have associated parathymic syndromes myasthenia gravis hypogammaglobulinemia pure red cell aplasia

48. 1/3 have chest pain, cough or dyspnea on presentation Myasthenia gravis occurs in 30-50% of pts with thymoma. Hypogammaglobulinemia occurs in 10% of pts with thymoma Pure red cell aplasia occurs in 5%, but thymoma occurs in 50% of pts with red cell aplasia

49. Thymoma lobulated mass in the anterior mediastinum

50. thymoma

51. Invasive thymoma Encasement of mediastinal structures, infiltration of fat planes, and an irregular interface between the mass and lung parenchyma, are highly suggestive of invasion. Pleural thickening, nodularity, or effusion generally indicates pleural invasion by the thymoma

52. Thymic Carcinoid carcinoid tumors (neuroendocrine tumors) of the thymus are very rare, accounting for <5% of all neoplasms of the anterior mediastinum. They originate from the normal thymic Kulchitsky cells, which belong to the amine precursor uptake and decarboxylation (APUD) group Presentation men aged 30 to 50 years (male/female ratio: 3:1) Rarely associated with carcinoid syndrome Associated endocrine abnormalities: Cushing’s syndrome due to ectopic ACTH or MEN 73% have regional lymph node and/or distant osteoblastic bone mets

53. Thymic carcinoid tumor in a 22-year-old man with a 3-month history of a persistent dry cough. Contrast-enhanced CT scan shows a heterogeneously enhancing thymic mass . PET image shows intense FDG uptake by the mass

54. Thymic Carcinoma Presentation M>F, 40s Thymic carcinomas are less common than thymomas, more aggressive with a higher propensity for capsular invasion Early local invasion, widespread lymphatic and hematogenous metastases Clinically, patients present initially with tussis, dyspnea, pleuritic chest pain, phrenic nerve palsy, or superior vena cava syndrome 80% of patients with thymic carcinoma may have radiographic evidence of invasion into adjacent structures in the mediastinum 40% may have evidence of mediastinal lymphadenopathy Distant metastases to regional lymphatics, bone, liver, kidney, and lung are a common clinical feature

55. Thymic Carcinoma Thymic carcinomas behave more aggressively than invasive thymomas and are more likely to metastasize to distant sites

56. Thymic Lymphomas Lymphoma is the most common cause of an anterior mediastinal mass in children and the second most common cause of an anterior mediastinal mass in adults.

57. cancers of the head and neck, abdomen, and pelvis can involve the thymus via lymphatic pathways Metastatic disease to the thymus in a 10-year-old boy 2 years after diagnosis of alveolar rhabdomyosarcoma of the thigh. Secondary Tumors of the Thymus

58. Mediastinal lymphoma

59. Primary Mediastinal Lymphoma 5-10% of patients with lymphoma present with primary mediastinal lesions Primary mediastinal lymphoma represents 10-20% of primary mediastinal masses in adults and are usually in the anterosuperior compartment Usually present with fever, weight loss and night sweats Pain, dyspnea, stridor, SVC syndrome due to mass effects are uncommon

60. Primary Mediastinal Lymphoma Two Types Primary Mediastinal Hodgkin’s Lymphoma Primary Mediastinal Non-Hodgkin’s Lymphoma Poorly differentiated lymphoblastic Diffuse lymphocytic Primary Mediastinal B-cell Lymphoma

61. Primary Mediastinal Hodgkin’s Lymphoma Presentation Incidental mediastinal mass on chest xray is 2nd most common presentation after asymptomatic lymphadenopathy Mass is usually large, rarely causes retrosternal chest pain, cough, dyspnea, effusions or SVC syndrome Bimodal age distribution “B” symptoms: fever, weight loss (>10% body wt in 6 months), night sweats Generalized pruritus present

62. A chest CT exam shows the mass to extend from the neck to the diaphragm, compressing the tracheal and left mainstem bronchus leading to left lower lobe atelectasis. The chest wall mass is partially eroding the sternum. Dx:Lymphoma, Hodgkin, Anterior Mediastinal, Sternal Involvement

63. Two contiguous slices from an enhanced chest CT exam show a homogenous, solid, anterior mediastinal mass and a large right pleural effusion. Dx-Lymphoma Non-Hodgkin, Anterior Mediastinal

64. Mediastinal Germ Cell Tumors Primary extragonadal germ cell tumors comprise 2% to 5% of all germ cell tumors Approximately two thirds of these tumors occur in the mediastinum The mediastinum is the most common site of primary extragonadal germ cell tumors in young adults Represent 10-15% of adult anterosuperior mediastinal tumors

65. they presumably arise from germ cells that migrate along the urogenital ridge during embryonic development . The embryologic urogenital ridge extends from C6 to L4 and after malignant transformation of displaced germ cells, explains the development of primary germ cell tumors outside the gonads Mediastinal Germ Cell Tumors

66. Mediastinal Germ Cell Tumors Three types Teratoma Seminoma Nonseminomatous Germ Cell Tumor

67. Mediastinal Teratomas Most common mediastinal germ cell tumor Three types: Mature: benign, well-differentiated Immature: contains >50% immature components, may recur or metastasize Malignant: a mature teratoma that contains a focus of carcinoma, sarcoma or malignant GCT

68. Mature Teratoma Occurs in children and young adults Usually asymptomatic, but if large enough, may cause chest pain, dyspnea, cough or other symptoms of mediastinal compression Contains derivatives of all three primitive germ layers including Ectoderm: teeth, skin, hair Mesoderm: cartilage and bone Endoderm: bronchial, intestinal and pancreatic tissue Expectoration of hair (trichoptysis) is rare but pathognomonic

69. Dx Teratoma, Anterior Mediastinal CT exam show a low density mass in the anterior mediastinum with irregular walls with calcium in it.

70. Mediastinal Seminoma Represents 40% of malignant mediastinal GCTs Afflicts Caucasian men in 20s-30s Only rarely represents a metastatic lesion from a testicular primary tumor, but testicular USG is usually performed to rule this out If any other germ cell tumor histology is identified in the tumor, it is treated as a mixed NSGCT AFP normal, β-HCG may be elevated in 10%

71. Mediastinal Seminoma Presentation Slow growing tumor, usually symptomatic at diagnosis Commonly presents with chest pain, dyspnea, cough, weight loss Presents infrequently with SVC syndrome Bulky, lobulated, homogeneous mass, no calcifications Usually not invasive, but many have metastasized to regional lymph nodes, lung and/or bone by the time of diagnosis

72. Mediastinal Nonseminomatous Germ Cell Tumors Five Types Embryonal cell carcinoma Endodermal sinus tumor: elevated AFP Choriocarcinoma: elevated β-HCG Malignant Teratoma Mixed

73. Mediastinal Nonseminomatous Germ Cell Tumors NSGCTs of the mediastinum have a worse prognosis than mediastinal seminomas or teratomas Occur in men in the 20-40 age group 20% of patients also have Klinefelter’s syndrome

74. Tracheal tumors Extremely rare tumors. Comprise of 0.1 to 0.4 %of all diagnosed malignancies Two types: squamous cell carcinoma M:F=3:1 Age:6 th decade adenoid cystic carcinomas M:F=1:1 younger age Clinical feature: cough, dysnoea, dysphagia,stridor hemoptysis, dysphonia

75. Clinical presentation of mediastinal mass

76. Clinical Presentation Asymptomatic mass Incidental discovery – most common 50% of all mediastinal mass are asymptomatic 80% of such mass are benign More than half are malignant if with symptoms

77. Clinical Presentation 1 Effects on Compression or invasion of adjacent tissues Chest pain , from traction on mediastinal mass, tissue invasion, or bone erosion is common Cough , because of extrinsic compression of the trachea or bronchi, or erosion into the airway itself Hemoptysis, hoarseness or stridor Pleural effusion, invasion or irritation of pleural space Dysphagia, invasion or direct invasioin of the esophagus Pericarditis or pericardial tamponade Right ventricular outflow obstruction and cor pulmona le

78. Clinical Presentation 2 Effects on Compression of nerves Hoarseness, invading or compressing the nerves recurrent laryngeal nerve Horners syndrome, involvement of the sympathetic ganglia Dyspnea, from phrenic nerve involvement causing diaphragmatic paralysis Tachycardia, secondary to vagus nerve involvemenT

79. Clinical Presentation Superior vena cava Vulnerable to extrinsic compression and obstruction because it is thin walled and its intravascular pressure is low. Superior vena cava syndrome Results from the increase venous pressure in the upper thorax , head and neck characterized by dilation of the collateral veins in the upper portion of the head and thorax and edema oand phlethora of the face, neck and upper torso, suffusion and edema of the conjunctiva and cerebral symptoms such as headache, disturbance of consciousness and visual distortion Bronchogenic carcinoma and lymphoma are the most common etiologies

80. Clinical Presentation Systemic symptoms and syndromes Fever, anorexia, weight loss and other non specific symptoms of malignancy .

81. Mediastinal mass: pre treatment evaluation

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