Leiomyoma of the urinary bladder in asymptomatic women.

Most bladder tumors are derived from the urothelium. Benign mesenchymal tumors are rare. Leiomyomas account for less than 0.43% of all bladder tumors. Genitourinary leiomyomata may arise in any anatomic structure containing smooth muscle. They have been reported to involve single or multiple organs. Since they may also mimic malignant lesions, they should always be considered in the differential diagnosis of any pelvic mass, with a possibility of being asymptomatic and discovered incidentally by radiographic imaging. We, herein, report a case illustrating clinical and pathological features in particular immunohistochemistry, and discuss its etiology and differential diagnosis.