Metastatic carcinoma of the prostate mimicking primary carcinoid tumor of the lung and mediastinum.

Although prostatic carcinomas rarely present as intrathoracic metastases, they may occasionally exhibit clinical and radiographic findings suggestive of a primary pulmonary carcinoid, particularly when they have a cribriform pattern. This report describes three patients who presented with lung and mediastinal neoplasms initially diagnosed as primary carcinoid tumors. These tumors were later proven to be metastatic prostate carcinoma by the use of immunohistochemical studies, including stains for chromogranin, carcinoembryogenic antigen and prostate specific antigen. These findings emphasize the importance of considering metastatic prostate adenocarcinoma in the differential diagnosis of carcinoid or neuroendocrine carcinoma with a cribriform pattern.