Histologic features of metastatic prostate cancer.

Prostate carcinomas begin as well-differentiated lesions. Before metastases occur these carcinomas dedifferentiate into moderately or poorly differentiated lesions and increase in size to at least 1 cm3. Well-differentiated lesions rarely metastasize and metastases are rarely well differentiated. Positive staging lymphadenectomies usually contain moderately differentiated metastases. Patients with moderately differentiated metastases have a statistically significant better survival than patients with poorly differentiated metastases. Metastases typically disseminate as they dedifferentiate, with stage D1 metastases being moderately differentiated and stage D2 metastases being poorly differentiated. "Prostate-specific" immunohistochemical techniques and serum prostate-specific antigen levels may be helpful in determining whether a particular metastases is from the prostate. However, metastases of uncertain origin should rarely, if ever, be attributed to the prostate without confirmation that the patient has a prostate carcinoma with histologic features capable of metastasizing.