Primary mediastinal carcinoid tumors.

A study of 15 cases of carcinoid tumor of the thymus, diagnosed and treated at the Mayo Clinic, revealed histopathologic features of the neoplasm that might cause it to be confused with other mediastinal tumors, both primary and secondary. The tumor was associated with ectopic ACTH production in six patients, of whom five had Cushing's syndrome. Metastasis, which occurred in 11 patients (73%), was delayed for as long as 8 years after initial diagnosis. Eleven patients underwent surgical resection of their primary thymic neoplasms, and nine of these received postoperative radiotherapy or chemotherapy or both. One patient was treated with chemotherapy alone, and three had no treatment for their neoplasms, which were discovered at autopsy. Eight patients are still alive. Of these, five have developed metastases, and only one is free of metastatic disease more than 5 years after diagnosis. In the two remaining cases, the discovery of the thymic tumor was recent and follow-up is not yet meaningful. Overall, four of the seven patients who died had proven metastatic disease. The mean survival after the appearance of extrathymic tumor in this group was 3 years. Of the five patients who are still alive with metastasis, all have survived at least 2 years since that spread of their disease.