Adenosquamous carcinoma of the prostate.

We describe a patient with adenosquamous carcinoma of the prostate. His history suggests a common histogenesis of the glandular and squamous elements of the tumor. A 60-year-old white man had adenocarcinoma of the prostate diagnosed by biopsy and then underwent radical prostatectomy, which showed adenosquamous carcinoma. Immunoperoxidase in the glandular component was positive for prostate-specific antigen (PSA), prostatic acid phosphatase (PAP), and low molecular weight keratin CAM 5.2 but was negative for high molecular weight keratin AE-3. The squamous component was negative for PSA, PAP, and CAM 5.2 but positive for AE-3. Previously reported patients with adenosquamous carcinoma of the prostate share a history of radiation or hormonal therapy followed much later by prostatectomy, suggesting that adenosquamous carcinoma consists of residual primary adenocarcinoma and metaplastic squamous epithelium caused by radiation or hormonal treatment. However, the present case lacks this history, suggesting that the two types of epithelia may have developed concurrently.