OBJECTIVETo study the clinicopathologic features, diagnosis and differential diagnosis of inflammatory myofibroblastic tumor of the urinary bladder.

METHODSExcisional specimens from 5 cases of vesical inflammatory myofibroblastic tumor were studied by light microscopy and immunohistochemistry (EnVision). The clinical data were also analyzed.

RESULTSAmong the 5 patients studied, 3 were males and 2 were females. The age of the patients ranged from 10 to 53 years (mean age = 35 years). The most common clinical presentation was micturition pain and hematuria. Three cases were located at the dome of the urinary bladder and the remaining 2 cases were found in the left lateral wall. Histologically, the tumor varied from myxoid to highly cellular. The tumor cells were spindle to stellate in shape, widely separated or showed a compact fascicular pattern. There were often associated with mixed inflammatory infiltrates and an irregular meshwork of small dilated vessels. Immunohistochemical study showed that the tumor cells expressed AE1/AE3 (5/5), vimentin (5/5), smooth muscle actin (5/5), calponin (5/5), caldesmon (3/5), desmin (4/5) and anaplastic lymphoma kinase protein (4/5). Follow-up data were available in 4 patients and none had local recurrence or died of this disease.

CONCLUSIONInflammatory myofibroblastic tumour of urinary bladder is a rarely encountered but distinctive neoplasm with intermediate malignant potential.