[A case report of prostatic stromal tumor of uncertain malignant potential (STUMP)].

Sarcomas and related proliferative lesions of specialized stroma of prostate are rare. Lesions have been classified into prostatic stromal tumor of uncertain malignant potential (STUMP) and prostatic stromal sarcoma (SS) based on the degree of stromal cellularity, presence of mitotic figures, necrosis, and stromal overgrowth. STUMPs are considered neoplastic, based on the observations that they may diffusely infiltrate the prostate gland and extend into adjacent tissues, and often recur. Although most cases of STUMP do not behave in an aggressive fashion, occasional cases have been documented to recur rapidly after resection and a minority have progressed to stromal sarcoma. Here we describe a case of STUMP. A 42-year-old male was seen at a hospital with the chief complaint of elevated levels of prostate specific antigen. Since digital examination revealed abnormal findings in the prostate, then he was referred to our hospital. We diagnosed STUMP by ultra-sound-guided needle biopsy of the prostate. Then we performed radical prostatectomy. Finally we made the pathological diagnosis of prostatic STUMP. Ten months later, there was no sign of metastasis or recurrence.