A case of prostatic stromal tumor of uncertain malignant potential

57歳男性.患者は頻尿を主訴に近医を受診, 直腸診にて前立腺腫瘤を指摘され, 著者らの施設へ紹介となった.入院時, 血清PSAの軽度上昇を認め, 経直腸エコーでは前立腺背側に精嚢へ突出する28×23×18mm大の内部不均一な腫瘤を認めた.経直腸エコーガイド下前立腺針生検の結果, leiomyosarcomaと診断し, 前立腺全摘術を施行したところ, 病理組織学的には前立腺原発のP-STUMPと診断され, 術後11ヵ月経過現在, 再発・転移は認められず, 経過も良好である
Sarcomas and related proliferative lesions of specialized prostatic stroma are rare. Lesions have been classified into prostatic stromal tumor of uncertain malignant potential (P-STUMP) and prostatic stromal sarcoma 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 STUMPs 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 P-STUMP. A 57-year-old male went to his family doctor because of pollakisuria. Digital examination revealed abnormal findings in the prostate, then he was referred to our medical center. The mass was palpable in the left lobe of the prostate; it was elastic hard, surface smooth, about 2 cm in diameter. Serum PSA was elevated slightly (5.42 mg /dl). We diagnosed firstly leiomyosarcoma by transrectal ultra sound guided needle biopsy of the prostate. Then we performed radical prostatectomy. Finally we made the pathological diagnosis of P-STUMP. After 11 months, there is no sign of metastasis or recurrence.