経尿道的膀胱腫瘍切除術後に発生した炎症性偽腫瘍

Inflammatory myofibroblastic tumor of the urinary bladder after TUR-Bt

　症例は46歳，男性。表在性膀胱癌の経過観察中に無症候性肉眼的血尿が出現し，膀胱鏡を施行したところ非乳頭状腫瘍が認められた。TUR-Btを施行し，炎症性偽腫瘍と診断した。根治的腫瘍切除を目的としてTUR-Btを施行し，術後5か月経過した現在，再発を認めていない。悪性腫瘍の診断で過大な手術を施行しないために，炎症性偽腫瘍を念頭に置き，鑑別することが重要である。

　A 46-year-old man with asymptomatic gross hematuria had three papillary bladder tumors cystoscopically. Pathological examination of the transurethrally resected specimen revealed urenary carcinoma,G2,pT1. Postoperative asymptomatic gross hematuria was persisted and cystoscopic examination showed a non-papillary tumor in the retrotrigone of the bladder. Pathological diagnosis of the tumor obtained by transurethral resection was an inflammatory myofibroblastic tumor consisted of spindle cells but without abnormal nuclear mitosis and positive staining for anaplastic lymphoma kinase. 5 months after TUR-Bt,there is no recurrence. Inflammatory myofibroblastic tumor of the urinary bladder is a rare benign entity that can easily be mistaken for a malignant neoplasm both clinically and histologically. It is important to identify inflammatory pseudotumor in order to avoid more invasive surgeries.