A clinicopathologic study of mediastinal lesions with special emphasis on thymomas
Keywords:Mediastinum, Thymomas, Myasthenia Gravis
Background: Mediastinal masses are relatively uncommon lesions that sometimes pose an interesting diagnostic and therapeutic problem for the clinician. Thymomas are one of the common mediastinal neoplasms and exhibit a wide spectrum of morphologic features and an unrivalled frequency of other autoimmune diseases. The great morphologic variability and heterogeneity in thymomas has rendered their histological classification difficult and highly controversial.
Methods: This retrospective and descriptive study on thymoma was done in the department of pathology, Kasturba Medical College Mangalore (Manipal University), India over a period of five years from January 2006 to June 2011. Histopathology sections taken were stained with routine Hematoxylin and Eosin stains in every case. Additional stains and immunohistochemistry were done as required.
Results: Total number of mediastinal lesions studied was 66, with thymomas making up 15 cases. The age range of patients with thymomas was 22 to 65 years with a mean of 48 years. The most common histologic sub-type of thymoma was B2. Type AB thymoma was associated with bad prognosis. Five cases of thymomas were associated with Myasthenia Gravis. All thymomas showed cytokeratin positivity. Reticulin fibers were seen around individual tumor cells in Type A thymoma while Type B2 showed around tumor nests.
Conclusion: Thymomas are rare & interesting neoplasm located in the mediastinum. A histomorphological analysis aided by immunohistochemistry and radiology permits an exact diagnosis and also allows for differentiation between benign and malignant neoplasms.
Kornstein MJ, deBlois GG. Pathology of the Thymus and Mediastinum. 1st edition. Philadelphia (PA): Saunders; 1995.
Kornstein MJ. Thymoma classification my opinion. Am J ClinPathol. 1999;112(3):304–7.
Marx A, Muller-Hermelink HK. Thymoma and thymic carcinoma. Am J SurgPathol 1999; 23(6): 739–42.
Suster S, Moran CA. Thymoma classification. The ride of the valkyries? Am J Clin Pathol. 1999;112(3):308–10.
Harris NL, Muller-Hermelink HK. Thymoma classification. A siren’s song of simplicity. Am J Clin Pathol. 1999;112(3):299–303.
Muller-Hermelink HK, Marx A. Towards a histogenetic classification of thymic epithelial tumours? Histopathol. 2000;36(5):466–9.
Lattes R. Thymoma and other tumors of the thymus: an analysis of 107 cases. Cancer. 1962;15(6):1224-60.
Lardinois D, Rechsteiner R, Lang RH, et al. Prognostic relevance of Masaoka and Muller-Hermelink classification in patients with thymictumors. Ann Thorac Surg 2000;69(5):1550–5.
Okumura M, Ohta M, Tateyama H, et al. The World Health Organization histologic classification system reflects the oncologic behavior of thymoma: a clinical study of 273 patients. Cancer. 2002;94(3): 624-32.
Nakagawa K, Asamura H, Matsuno Y, et al. Thymoma: a clinicopathologic study based on the new World Health Organization classification. J Thorac Cardiovasc Surg 2003;126(4):1134–40.
Shrivastava CP, Devgarha S, Ahlawat V. Mediastinaltumors: A clinicopathological analysis. Asian Cardiovasc Thorac Ann. 2006;14(2):102-4.
Conkle DM, Adkins RB Jr. Primary malignant tumors of the mediastinum. Ann Thorac Surg. 1972;14(5):533-67.
Rubush JL, Gardner IR, Boyd WC, Ehrenhaft J L. Mediastinaltumors: review of 186 cases. J Thorac Cardiovasc Surg. 1973;65(2):216-22.
Dubashi B, Cyriac S, Tenali SG. Clinicopathological analysis and outcome of primary mediastinal malignancies – A report of 91 cases from a single institute. Ann Thorac Med. 2009;4(3):140-2.
Azarow KS, Pearl RH, Zurcher R, Edwards FH, Cohen AJ. Primary mediastinal masses: A comparison of adult and pediatric populations. J Thorac Cardiovasc Surg. 1993;106(1):67-72.
Davis RD, Oldham HN Jr, Sabiston DC Jr. Primary cysts and neoplasms of the mediastinum: recent changes in clinical presentation, methods of diagnosis, management, and results. Ann Thorac Surg. 1987;44(3):229–37.
Cohen AJ, Thompson L, Edwards FH, Bellamy RF. Primary cysts and tumors of the mediastinum. Ann Thorac Surg. 1991;51(3):378-84.
Mullen B, Richardson JD. Primary anterior mediastinaltumors in children and adults. Ann Thorac Surg. 1986;42(3):338-45.
O’Gara RW, Horn RC Jr, Enterline HT. Tumors of the anterior mediastinum. Cancer. 1958;11(3):562-90.
Bernatz PE, Harrison EG, Clagett OT. Thymoma: a clinicopathologic study. J Thorac Cardiovasc Surg. 1961;42:424-44.
Salyer WR, Eggleston JC. Thymoma: a clinical and pathological study of 65 cases. Cancer. 1976;37(1):229-49.
Suster S, Rosai J. Cystic thymomas: a clinicopathologic study of ten cases. Cancer 1992;69(1):92-7.
Gripp S, Hilgers K, Wurm R, Schmitt G. Thymoma: Prognostic factors and treatment outcomes. Cancer. 1998;83(8):1495-503.
Moran CA, Suster S. Thymoma with prominent cystic and hemorrhagic changes and areas of necrosis and infarction: a clinicopathologic study of 25 cases. Am J Surg Pathol. 2001;25(8):1086-90.
Lewis JE, Wick MR, Scheithauer BW, Bernatz PE, Taylor WF. Thymoma: a clinicopathologic review. Cancer. 1987;60(11):2727-43.
Masaoka A, Monden Y, Nakahara K, Tanioka T.Follow-up study of thymomas with special reference to their clinical stages. Cancer. 1981;48(11):2485-92.
Chen G, Marx A, Chen WH, et al. New WHO classification predicts prognosis of thymic epithelial tumors: A clinicopathologic study of 200 thymoma cases from China. Cancer. 2002;95(2):420-9.
Moran CA, Suster S. On the histologic heterogeneity of thymic epithelial neoplasms. Impact of sampling in subtyping and classification of thymomas. Am J Clin Pathol. 2000;114(5):760-6.
LeGolvan DP, Abell MR. Thymomas. Cancer. 1977; 39(5):2142-57.
Verley JM, Hollmann KH. Thymoma: A comparative study of clinical stages, histologic features, and survival in 200 cases. Cancer. 1985; 55(5): 1074-86.
Legg MA, Brady WJ. Pathology and clinical behavior of thymomas: a survey of 51 cases. Cancer. 1965;18:1131-44.
Pan CC, Chen PC, Wang LS, Chi KH, Chiang H. Thymoma is associated with an increased risk of second malignancy. Cancer. 2001;92(9):2406-11.
Osserman KE, Genkins G. Studies in myasthenia gravis: review of a twenty-year experience in over 1200 patients [abstract]. Mt Sinai J Med. 1971;38(6):497-537.
Marx A, Muller-Hermelink HK, Strobel P. The role of thymomas in the development of myasthenia gravis [abstract]. Ann N Y Acad Sci. 2003;998:223-36.
Seybold WD, McDonald JR, Clagett OT, Good CA. Tumors of the thymus. J Thorac Surg. 1950;20:195-214.
Wilkins EW Jr, Edmunds LH Jr, Castleman B. Cases of thymoma at the Massachusetts General Hospital. J Thorac Cardiovasc Surg. 1966;52(3):322-30.