Occult prostate adenocarcinoma with pulmonary metastasis: diagnosis by fine needle aspiration biopsy of the lung and immunohistochemistry.

Metastatic pulmonary nodules were found in a 70-year-old man, who also had osteoblastic bone lesions and symptoms of prostatism. Extensive searching, including a transurethral resection of the prostate, failed to establish the primary site of the malignancy. One of the pulmonary nodules was biopsied using a fine needle aspiration technique, and revealed adenocarcinoma. The tumor cells in this lesion stained positive for prostate specific antigen. The patient was treated with estrogen for prostatic carcinoma and improved.