Thymic hyperplasia and neoplasia: a review of current concepts.

摘要: Summary Although the term thymic hyperplasia is used most commonly to indicate occurrence of germinal centers in thymus, cognizance must be taken fact that such m.ay occur apparently normal thymuses both children and adults. A concept compartmentalization proposed with origin perivascular space (extraparenchymal compartment) thyrnus. These contain a high percentage B lymphocytes contrast true parenchyma. significance thymus myasthenia gravis remains controversial, removal nonneoplastic this condition proven therapeutic value. variety neoplasms originating have previously been lumped together under single "thymoma". It apparent, however, thymoma, carcinoid, various lymphomas, germ cell tumors arise differ not only pathologically but also their clinical behavior. Thymoma regarded as an epithelial neoplasm ultrastucturally characterized by many desmosomes tonofilaments. The do behave malignant manner, lymphomas should sharply separated from thymoma. Poorly differentiated carcinoma histiocytic lymphoma may distinguishable electron microscopic demonstration filaments carcinoma. evidence Hodgkin's disease ("granulomatous thymoma") variant thymoma appears overwhelming. Lymphoblastic distinctive especially prevalent teenage males. High levels terminal transferase characterize lymphoblasts there striking tendency for leukemia occur. Thymic carcinoid usually nonfunctional, although one-third reported cases are associated Cushing's syndrome. On light microscopy ribbon pattern punctate necroses characteristic carcinoids. Electron dense core granules invaluable establishing diagnosis. An important clue diagnosis seminoma (a shows same radiosensitivity its testicular counterpart) frequent presence epithelioid giant granulomas centers. Separation described justifiable on pathologic grounds often essential appropriate patient investigation treatment.