Bladder leiomyomas, although rare (0.43% of bladder tumors), represent the most common non-epithelial / mesenchymal tumor of the urinary bladder.  Leiomyomas arise in the submucosa, but growth is most commonly intravesical (as in this case) rather than extravesical. They are smooth, solid, homogeneous masses. Cystic components indicate degeneration. At cystoscopy, the mass may not be evident as normal bladder mucosa may cover the leiomyoma. MR imaging remains superior in demonstrating the submucosal origin of the tumor and the preservation of the muscle layer.

Other urinary bladder masses to be considered include urothelial (transitional) cell carcinoma especially if it exhibits multiplicity, and rarely, leiomyosarcoma (if with necrosis), pheochromocytoma, lymphoma, sarcoma, and metastases.