Carcinoid tumor of the thymus: report of two cases.

Carcinoid tumors of the thymus are rare. In 1972, Rosai and Higa first described these neoplasms as a distinct entity from thymomas. Clinically, they may be asymptomatic or present with symptoms of a growing mass and/or with ectopic endocrine secretion. Two cases of thymic carcinoid tumor without endocrine manifestations are presented. Microscopically, both tumors showed typical features of carcinoid, such as ribbons, festoons and rosette-like structures. Immunohistochemically, they were immunoreactive for neuron-specific enolase (NSE), chromogranin A and keratin. Electron microscopic examination was performed only in one case and numerous dense core neurosecretory granules were demonstrated. Thymic carcinoid tumors may pursue an aggressive but protracted clinical course. Along with radiotherapy and possibly adjunctive chemotherapy, complete surgical excision remains the best treatment today either for the primary tumor or for subsequent recurrences.