The prostatic gland: malignancies other than adenocarcinomas.

Many rare variants of prostatic carcinoma have been described and characterized in recent years. Accurate diagnosis of these variants is necessary in order to determine appropriate therapy. Unusual tumors arising in the prostate raise questions of histogenesis, and may carry a better or worse prognosis than typical adenocarcinoma. Virtually the entire spectrum of cellular differentiation has been observed within prostatic epithelium, and rare neoplasms exhibit these unusual forms of differentiation as the chief component of the tumor. Except in sarcoma (marked prostatic enlargement), imaging plays a limited role in the diagnoses of these entities. Biopsy and histologic diagnoses are essential and the role of imaging is restricted to the evaluation of locoregional and distant spread of the disease.