Myxoid malignant fibrous histiocytoma of the bladder.

Although the most common soft tissue sarcoma of adulthood, malignant fibrous histiocytoma (MFH) is an extremely rare tumor of the urinary bladder. Only three well-documented cases have been reported in the world literature. The patient presented in this report represents the first case of the myxoid variant to develop in the urinary bladder. Whereas all previous patients with MFH of the bladder had intermittent hematuria, this patient's chief complaint was bladder outlet obstruction due to extension of the tumor into the prostate. He was managed with radical cystoprostatectomy, postoperative radiation therapy to the tumor bed, and adjuvant chemotherapy using doxorubicin. The patient tolerated the therapy well and was disease-free at the 3-year follow-up visit. The histogenesis, clinical features, pathologic characteristics, and treatment considerations of this rare bladder tumor are discussed in detail.