Primary Adenosquamous Carcinoma of the Prostate.

Prostate cancer accounts for 29% of malignant diagnoses among men in the United States and is the second leading cause of death from cancer. Effective screening methods and improved treatment have decreased the mortality rate significantly. This decreased mortality rate, however, does not apply to all histologic variants. Adenosquamous carcinoma of the prostate is an extremely aggressive neoplasm with no current known curative therapy. It is often diagnosed after chemotherapy, radiation, or androgen deprivation therapy for traditional prostatic adenocarcinomas. Primary carcinomas of the prostate with squamous features include, but are not limited to, pure squamous cell carcinoma and adenocarcinoma mixed with squamous cell carcinoma (SCC). Important distinguishable clinical features of adenosquamous carcinoma include normal prostate-specific antigen (PSA) levels, even with advanced disease and osteolytic versus osteoblastic metastatic lesions in adenocarcinoma. Additional entities to consider in the differential diagnosis are squamous metaplasia of the prostate, secondary involvement of pure SCC, and urothelial carcinoma with squamous differentiation. Here, we present a de novo case of adenosquamous carcinoma in a 48-year-old man who rapidly developed extensive metastatic disease.