Transrectal ultrasound appearance of radiation-induced prostatic sarcoma

BACKGROUND. Delayed development of prostatic sarcoma is a rare complication of prostatic pelvic irradiation. The transrectal ultrasound appearance of this lesion has not been previously described. METHODS. Three cases of radiation-induced prostatic sarcoma are presented, with emphasis on the transrectal ultrasound findings. RESULTS. An irregular, hypoechoic prostatic mass with an anechoic area consistent with the echogenicity of muscle and/or necrosis was found in all 3 patients. This appearance is distinctly dissimilar from prostatic adenocarcinoma. CONCLUSIONS. The sonographic finding of an irregular, hypoechoic prostatic mass with an anechoic area should raise suspicion for prostatic sarcoma in patients with a history of pelvic irradiation who develop an abnormal prostate on rectal examination and/or worsening voiding symptoms despite a normal serum prostate-specific antigen level.