The various types of spindle-cell lesions of the bladder can be difficult to distinguish because their clinicopathologic features overlap considerably, even between benign and malignant lesions. This problem can become most acute during an intraoperative consultation wherein the urologist must decide the extent of a cystectomy. In this review of the pathologic differential diagnosis of spindle-cell bladder lesions, a case of inflammatory (myofibroblastic) pseudotumor of the bladder will be presented to help illustrate the difficulties in making the diagnosis. Recognizing inflammatory (myfibroblastic) pseudotumor of the bladder requires a high index of suspicion. Inflammatory (myofibroblastic) pseudotumors are fibromyxoid spindle-cell tumors that usually occur in relatively young patients who have no history of surgery of other procedure to the area. They show normal mitotic figures (few), have a delicate granulation tissue-like vascularity, contain chronic of mixed inflammatory infiltrates, reveal minimal nuclear atypia, and rarely display tumor necrosis, except adjacent to the ulcerated surface. Electron microscopy reveals reactive myofibroblasts, and immunohistochemical stains often show both cytokeratin and desmin reactivity in the spindled tumor cells. For the unaware, this immunophenotype can lead to an overdiagnosis of either sarcomatoid carcinoma or a form of myogenic sarcoma. Although inflammatory (myofibroblastic) pseudotumors may recur locally, their prognosis is very good following complete or incomplete resection. Thus far, there have been no reported metastases.