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Leiomyosarcoma of the Urinary Bladder: A Clinicopathologic and Immunohistochemical Study of 15 Cases

We present the clinicopathologic and immunohistochemical features of 15 vesical leiomyosarcomas. The nine male and six female patients ranged in age from 16 to 72 years (median: 49 years). Gross hematuria was the most common complaint. The tumors most often arose in the dome of the bladder (50%) and ranged in size from 1 to 10 cm (median: 5 cm). Five patients underwent total cystectomy, nine had a partial cystectomy or local excision, and one was only biopsied. Based on the highest of five sets of mitotic counts per case, eight tumors had one or fewer mitotic figures per 10 high-power fields (MF/10HPF); none of these patients developed metastases during a follow-up interval of 1 month to 20 years (mean: 62 months). Five tumors showed three to six MF/10HPF; one patient in this group died after 6 years with unresectable metastases, whereas the others are disease free with follow-up of 8 months to 8 years (mean: 62 months). Two tumors contained 10–15 MF/10HPF; one produced widespread metastases and was fatal after 3 months, whereas the other has not recurred or metastasized after 9 months. All tumors had infiltrating margins and invaded the bladder musculature—important features in their distinction from vesical leiomyoma. Nine leiomyosarcomas had zones of myxoid intercellular material; six of these were predominantly or exclusively myxoid. The myxoid foci often closely resembled inflammatory pseudotumor, particularly in superficial portions of the neoplasms. In two cases, an intense superficial plasma cell infiltrate mimicked a plasma cell granuloma. All 12 leiomyosarcomas studied immunohistochemically were negative for epithelial markers (cytokeratins and epithelial membrane antigen); staining for muscle-specific actin and vimentin was uniformly positive, and eight neoplasms also expressed desmin.