Myxoid leiomyosarcoma of the urinary bladder.

A 16-year-old male patient with hematuria was found to have a 3-cm mass on the right posterolateral wall of the urinary bladder. After a biopsy specimen disclosed a myxoid tumor, a partial cystectomy was performed. The specimen contained a gelatinous tumor that, on microscopic examination, was a myxoid leiomyosarcoma similar to the neoplasm recently described in the uterus and several other locations. This tumor, which is the first of its type (to our knowledge) reported to occur in the bladder, must be distinguished from other neoplasms and nonneoplastic lesions that occur in this organ. The patient is well two years postoperatively.