Successfully reported this slideshow.

Pathology of mediastinal masses


Published on

Published in: Health & Medicine
  • Be the first to comment

Pathology of mediastinal masses

  1. 1. Pathology of Mediastinal Tumors By Osama El-Zaafarany
  2. 2. Anatomy  The mediastinum is the space between: • • • the thoracic inlet & the diaphragm, The sternum & vertebral column, The 2 lungs.  Compartments: • Anterior. • Superior. • Middle. • Posterior.
  3. 3.    The anterior mediastinum: thymus, lymph nodes, and small vessels. The middle mediastinum: the heart, proximal great vessels, central airway structures, and lymph nodes. The posterior mediastinum: sympathetic chain ganglia, vagus nerve, thoracic duct, and esophagus
  4. 4. DD of Mediastinal Mass  Antero-superior mediastinum:  Thymic tumors: Thymomas, Thymic carcinomas, Thymic cysts.  Lymphomas: Hodgkin's disease, Non-Hodgkin's lymphomas.  Germ cell tumors: Seminomas, Non-seminomas.  Endocrine tumors: Parathyroid adenomas, Thyroid tumors (retrosternal).  Mesenchymal tumors: Lipoma, liposarcoma, haemangioma, lymphangioma….
  5. 5. DD of Mediastinal Mass  The middle mediastinum:        Lymphomas. Cysts: Bronchogenic,pericardial,thoracic duct. Mesenchymal tumors. Tracheal tumors. Cardiac and pericardial tumors Vascular tumors: e.g. Aortic aneurysm. Lymphadenopathy: Inflammatory, Granulomatous, Sarcoidosis.
  6. 6. DD of Mediastinal Mass  The posterior mediastinum:   Lymphomas Neurogenic tumors: Peripheral nerves: Schwannomas Sympathetic ganglia: Ganglioneuromas, Neuroblastomas Paraganglia: Paragangliomas      Mesenchymal tumors Esophageal tumors and cysts Hiatal hernias. Thoracic duct cyst. Meningocele.
  7. 7. Thymic Tumors thymus gland • • • is an irregular lobulated lympho-epithelial organ in the anterior mediastinum. derived from the endoderm of third pharyngeal pouch. involutes during adulthood, gradually being replaced by adipose tissue. (I) Thymoma:  Thymomas are epithelial tumors associated with an exuberant lymphoid component composed of immature cortical thymocytes.  Thymomas are exceedingly rare.  incidence of 0.15 per 100,000 person-years.  higher in males than females.
  8. 8. ‫‪Thymoma‬‬ ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬
  9. 9. Thymoma ‫ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬    characterized by an indolent growth pattern that can be locally invasive. Long survival. myasthenia gravis is present in 30% to 40% of patients;(The cardinal features are weakness and fatigability of skeletal muscles)  81 % of recurrences are local, 9% distant.
  10. 10. Thymoma Pathological Classification: (WHO) Type A: tumors are composed of neoplastic oval or spindle-shaped epithelial cells without atypia or lymphocytes. Type AB: is similar to type A, but with foci of lymphocytes. Type B: tumors consist of plump epithelioid cells and are subdivided into three subtypes. Type B1 tumors resemble normal thymic cortex with areas similar to thymic medulla. Type B2 have scattered neoplastic epithelial cells with vesicular nuclei and distinct nucleoli among a heavy population of lymphocytes; perivascular spaces are prominent. Type B3 is composed of predominantly round or polygonal epithelial cells exhibiting mild atypia admixed with a minor component of lymphocytes; have described as well-differentiated thymic carcinoma. Type C: Thymic carcinomas these have clear-cut cytologic atypia and a cytoarchitecture resembling carcinoma distinctively unlike normal thymus tissue
  11. 11. Thymoma ‫ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ Masaoka Staging System     I : Macroscopically completely encapsulated, with no microscopic capsular invasion II :  IIa: Macroscopic invasion into surrounding mediastinal fatty tissue or mediastinal pleura.  IIb: Microscopic invasion into the capsule III : Macroscopic invasion into surrounding organs IV :  IVa: Pleural or pericardial implants/dissemination  IVb: Lymphogenous or hematogenous metastases
  12. 12. Thymoma ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬  Treatment: • Surgical resection is the mainstay of treatment for thymomas, and complete en- bloc surgical resection (R0) remains the treatment of choice for all thymomas regardless of invasiveness. • Radiation therapy is often considered for the adjuvant setting in patients with resected stage II and III thymomas. And still others recommend radiation only in the circumstance of incomplete resection.
  13. 13. Thymoma, Treatment ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬  Chemotherapy: • Thymomas have proven to be very sensitive to chemotherapy. • A clinical response is seen in roughly two thirds of patients. • The duration of response ranges from 12 to 93 months. • The most promising use of chemotherapy is in the neoadjuvant setting; appears to be effective at rendering tumors more amenable to a complete resection. • The commonly employed drugs in combination chemotherapy are cisplatin, doxorubicin, and cyclophosphamide. • May be combined with post-operative radiotherapy for stages III and IV.
  14. 14. (II) Thymic Carcinoma:     Thymic carcinomas are less common than thymoma. arise from thymic epithelium. more aggressive with a higher propensity for capsular invasion. frequently present with advanced disease and have a poorer 5-year survival than with thymomas
  15. 15. Thymic Carcinoma ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬  The majority of thymic carcinomas are undifferentiated high-grade lesions with: • Anaplasia. • marked cellular atypia. • lacking the histologic features of a normal thymus.    Others: adenocarcinomatous, sarcomatous, squamous, basaloid, mucoepidermoid, or lymphoepithelial like. 60% expression of CD5, CD70 and CD117 in epithelial cells. Current management requires an aggressive multimodality approach, including primary surgical resection and the use of adjuvant cisplatin-based chemotherapy, often coupled with postoperative radiation therapy.
  16. 16. (III) Thymic Carcinoid:     Thymic carcinoid tumors (neuroendocrine tumors) of the thymus are very rare. They originate from the normal thymic Kulchitsky cells, which belong to the amine precursor uptake and decarboxylation (APUD) group. Approximately 50% are associated with endocrine disorders, such as multiple endocrine neoplasia (MEN -1), or secondary Cushing's syndrome. Complete surgical resection is the preferred method of treatment, although recurrence is common.
  17. 17. Malignant Mediastinal Germ Cell Tumors     The mediastinum is the most common site of primary extragonadal germ cell tumors in young adults. A number of malignant processes are associated with nonseminomatous germ cell tumors; acute myeloid leukemia and malignant histiocytosis. Arise from germ cells that migrate along the urogenital ridge during embryonic development, which extends from C6 to L4. Meticulous work-up must be performed to prevent overlooking an occult gonadal primary, including testicular ultrasound.
  18. 18. Malignant Mediastinal Germ Cell Tumors ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬     Primary mediastinal germ cell tumors have the same morphologic and histologic appearance as those of the testes. They are divided into seminomatous and non-seminomatous tumors. Have a poor prognosis and aggressive behavior. Tumor markers can aid in diagnosis: The Alpha-fetoprotein (AFP) is elevated in 75% of patients. • The β-subunit of human chorionic gonadotropin (β-HCG) is elevated less than half of the time. • Lactate dehydrogenase (LDH) is elevated in 50% of patients. •  Main line of treatment is chemotherapy.
  19. 19. Mediastinal Neurogenic Tumors    Arise in the posterior mediastinum from peripheral nerves, sympathetic ganglia, or mediastinal chemoreceptors. Neuroblastoma is an aggressive variant of neurogenic tumors and is a disease of childhood. In adults, the majority of neurogenic tumors are benign schwannomas and neurofibromas in the setting of neurofibromatosis type 1 (NF-1) or von Recklinghausen's disease.
  20. 20. Mediastinal Neurogenic Tumors ‫ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬    Paragangliomas are rare tumors that arise from extra-adrenal paraganglia and potentially are catecholamine secreting. Most tumors are benign (~10% malignant), and surgical resection is usually curative. Malignant peripheral nerve sheath tumors (MPNSTs) have increased risk in Patients with NF-1. MPNSTs are difficult to detect, metastasize rapidly, and thus carry a poor prognosis.
  21. 21. Mediastinal Neurogenic Tumors ‫ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬     Management for patients with malignant mediastinal neurogenic tumors entails a multidisciplinary approach similar to the management of adult soft-tissue sarcomas. Surgical resection is the mainstay of therapy, and an R0 resection should be attempted. Adjuvant radiation has been incorporated into the management of localized MPNSTs. Unresectable disease, radiation can be delivered either alone or with chemotherapy that is used for soft-tissue sarcomas; doxorubicin, ifosfamide.