Mediastinal endocrine neoplasm, of probable thymic origin, related to carcinoid tumor. Clinicopathologic study of 8 cases

Abstract

Eight cases of a primary mediastinal endocrine neoplasm with the appearance of carcinoid tumor are presented, and the 8 cases previously reported are reviewed. These neoplasms occur in adults, most often in males, and are located in the anterior or anterosuperior mediastinum. The only effective treatment is surgical excision. Their natural history is similar to carcinoid tumors of other locations, especially those arising from derivatives of the foregut. They are characterized microscopically by formation of rosettes, ribbons, and festoons; sheet‐like or medullary areas; and large “balls” with central necrosis and calcification. Their cytoplasm contains argyrophil granules and, by electron microscopy, “neurosecretory” granules. Some features of these neoplasms favor an origin from the thymus gland. However, they should be clearly separated from thymomas because of their different histogenesis, microscopic appearance, and natural history. It is suggested that the so‐called “epithelial thymoma” associated with Cushing's syndrome is related to the neoplasm discussed here. Copyright © 1972 American Cancer Society