Conference Coverage

Presentation of A Rare Malignancy: Leiomyosarcoma of the Prostate

Abstract: 2018 AVAHO Meeting


 

Background: Prostatic leiomyosarcoma is a rare tumor that accounts for less than 0.1% of all primary prostatic malignancies. This neoplasm is composed of highly aggressive prostatic smooth muscle cells that presents with nonspecific signs and symptoms mimicking other forms of prostatic pathology.

Case Report: A 72-year-old male presented with 6 months of progressive severe lower urinary tract symptoms (LUTS) secondary to bladder outlet obstruction. The patient was refractory to medical management and required multiple emergent bladder catheterizations. Workup with urinalysis, blood biochemistry, and PSA levels were persistently normal. He denied hematuria, weight loss, or perineal pain. On rectal exam, a mass like induration was noted along the right upper lobe of the prostate.

The patient was referred for transurethral resection of the prostate (TURP) for suspected severe BPH. Histopathological examination demonstrated atypical cytology consistent with high-grade leiomyosarcoma. A PET scan revealed a 1.9 cm tumor with uptake of 12.6 SUV in the right posterior prostate.

Discussion: Fewer than 200 cases of prostatic leiomyosarcoma have been reported. Patients typically present between 41-78 years of age (mean age of 61 years) with signs and symptoms related to LUTS (89.4%) and perineal or rectal pain (25.6%). Constitutional symptoms, burning on ejaculation, and hematuria are uncommon. PSA levels remain normal, due to its non-epithelial etiology, which may contribute to delays in diagnosis.

Diagnosis is usually achieved after a TURP procedure or transrectal needle biopsy. Pathology demonstrates neoplastic spindle cells with nuclear atypia, multifocal necrosis, and cystic degeneration. Immunohistochemistry is characteristically positive for desmin, smooth muscle actin, and vimentin. Tumors have been reported to range between 2-31 cm in size, frequently presenting with invasion of local structures. The lungs are the most common site of distant metastasis.

Treatment may include a multimodal approach of surgery, radiation, and chemotherapy. Long-term prognosis is poor due to the tumors aggressive nature, and recurrence is common. Median survival is estimated at 17 months and 50-75% of patients die within 2-5 years of diagnosis. Due to the substantially high risk of death, prostatic leiomyosarcoma may be one of the most aggressive and poorly prognostic malignancies involving the prostate.

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