Small cell carcinoma of the prostate is a high-grade malignant neoplasm with neuroendocrine differentiation. The morphologic features characteristic of the disease’s pathology include small tumor cells with minimal cytoplasm, nuclear molding, fine chromatin pattern, extensive tumor necrosis/apoptosis, and a brisk mitotic rate.
Small cell carcinoma of the prostate is rare, accounting for less than 1% of all prostate cancers. Approximately 50% of patients have pure small cell carcinoma at initial presentation. Some 25-50% of cases are mixed with a conventional prostatic adenocarcinoma.
Another 25-40% of cases are initially diagnosed as prostatic adenocarcinoma and recur as small cell carcinoma after hormonal therapy. The median interval between initial diagnosis of prostatic adenocarcinoma and recurrence of small cell carcinoma is 25 months. Unlike prostatic adenocarcinoma, small cell carcinoma of the prostate may present with metastases in up to 25% of patients.
The distribution of prostatic small cell carcinoma is similar to that of prostatic adenocarcinoma. Most patients have multifocal disease but also have a dominant nodule located in the peripheral zone. These tumors may be felt by digital rectal examination and can be diagnosed by needle core biopsy. The transitional zone and central zone are not common locations for clinically important prostate cancers.