Carcinoid tumor arising in a treated primary germ cell tumor of the mediastinum.

: A 33-year-old man had a locally aggressive anterior mediastinal carcinoid tumor, manifested as an enlarging mass refractory to chemotherapy two years after initially successful treatment of a primary germ cell tumor. Ultrastructurally, the tumor contained dense-core endocrine-type secretory granules. Many mediastinal carcinoid tumors have been reported, but we found no examples of such a tumor arising as a sequel to or as a refractory component of a mediastinal germ cell tumor after initially effective therapy.