Prostatic adenocarcinoma metastatic to the head and neck and the workup of an unknown epithelioid neoplasm

Background. Epithelioid tumors in the head and neck are common and include both primary and metastatic lesions. For metastatic lesions, clinical factors, tumor location, and ancillary immunohistochemical studies must be taken into consideration to help the clinician and the pathologist determine the site of origin. One unusual, but important, primary tumor that can metastasize to the head and neck is carcinoma of the prostate (CAP). Methods. The files of the University of Pennsylvania Department of Pathology were searched for cases of metastatic CAP. All slides were examined, and clinical information was obtained from the referring physician's patient charts. Results. We describe 14 cases of metastatic CAP to the head and neck. Six patients had no history of CAP at the time of biopsy of the head and neck metastasis, and only eight patients had other widespread metastatic disease. Histologically, most of the tumors had epithelioid cells with prominent nucleoli and cribriform, solid, or infiltrating single cell growth patterns. PSA and PSAP immunohistochemical stains were positive in all cases. Seven of 12 patients with known follow-up are alive after radiation or hormonal therapy. Conclusions. These results demonstrate a fair prognosis with possible prolonged survival with metastatic CAP to the head and neck after appropriate diagnosis and subsequent hormone and radiation therapy. Given this survival advantage with treatment, it is critical to consider the diagnosis of metastatic CAP when evaluating a metastatic malignant ephitelioid tumor in the head and neck of an elderly man.