[A case of stromal tumors of uncertain malignant potential treated by radical prostatectomy]. 
A 56-year-old man visited a local hospital after experiencing urinary frequency for five years.  A digital rectal examination revealed a markedly enlarged prostate and his serum prostate specific antigen (PSA) was 9.0 ng/ml.  Although the first transrectal biopsy could not determine the final diagnosis due to insufficient sampling, the additional biopsy revealed prostatic stromal tumor of uncertain malignant potential.  Magnetic resonance imaging and computed tomography showed an organ-confined huge prostate tumor.  We performed radical prostatectomy uneventfully and the specimen weighed 141 g. One year after the operation, the patient had no urinary symptoms and no evidence of disease recurrence.