AbstractAn unusual type of prostatic carcinoma associated with crossed renal ectopia and dermatomyo-sitis is reported in a young man. Infiltration by an epithelial tumor filled the enlarged prostate with soft papillary masses. Cystoprostatectomy and removal of a single large pelvic lymph node metastasis were done. Histologically, the tumor resembled endometrial carcinoma and may have arisen from paramesonephric tissue in the prostate. Large amounts of immunoglobulins were found in the tumor tissue. The patient has survived for more than 5 years, although a slow growing urethralrecurrence has been noted.