Malignant mixed tumor of the salivary-gland type, primary in the prostate.

A previously undescribed malignant mixed tumor arising in the prostate of a 72-year-old man is herein presented. Clinically, it was manifested by slowly progressing urinary frequency and urgency, as well as by intense pain. The total serum acid phosphatase value and the prostatic fraction were within normal limits. Six months after prostatectomy the patient died, with local recurrence and roentgenologic evidence of a single pulmonary metastasis. Both light-microscopic and electron-microscopic examination showed features similar to those of a malignant mixed tumor of the salivary gland. These findings suggest that this tumor originated in seromucinous ectopic glands. The important factor in its recognition is that it is not hormone-dependent.