PRIMARY PROSTATIC LEIOMYOSARCOMA

Leiomyosarcoma of the prostate is rare, accounting for less than 0.1% of prostate malignancies with only 23 cases reported in the literature.1 It has a poor prognosis, although the length of survival is variable. We report a case of primary prostatic leiomyosarcoma in a boy. CASE REPORT A 14-year-old boy presented with perineal pain during defecation and voiding for 5 months, dysuria and hematuria. Digital rectal examination revealed an indurated left prostatic lobe. Excretory urography showed an anteriorly displaced bladder compressed by a large pelvic mass on lateral view. However, examination of the upper urinary tract was normal. Computerized tomography of the abdomen and pelvis revealed a 15 3 11 cm. multiseptated pelvic mass with thickened irregular walls displacing the bladder and rectum (fig. 1). Surgical biopsy of the mass performed elsewhere demonstrated a smooth muscle neoplasm with no features that could exclude leiomyoma. Pelvic lymph node dissection and radical cystoprostatectomy were performed. The 580 gm. radical prostatectomy specimen contained an uncircumscribed tumor on the left side, extending from the apex to the base. Microscopic examination revealed an infiltrative neoplasm invading and displacing the normal prostate stroma and glands with abnormal mitotic figures and giant cells. Necrosis was present and mitotic counts were 14/10 high power fields. On immunohistochemistry the tumor displayed intense cytoplasmic immunoreactivity for actin, desmin and vimentin (fig. 2) but was negative for keratin and S100 protein. Extraprostatic extension of the tumor as well as involvement of the margin of resection was documented. Examination revealed 3 left iliac nodes with metastatic tumor. The patient received 46 Gy. adjuvant radiotherapy. He died of lung, liver and bone metastases with gross local recurrence 4 months after diagnosis. DISCUSSION