[Malignant mixed Müllerian tumor of the urinary bladder]

True mixed epithelial-mesenchymal tumors of the urinary bladder are exceedingly rare, and only two vesical adenosarcomas have been reported to date. These tumors originated from bladder endometriosis, and malignant transformation of endometriosis has been described, with endometrioid and clear-cell carcinomas being the most common malignancies. We report an unusual case of a malignant mixed Müllerian tumor with heterologous rhabdomyoblastic differentiation, which originated in the urinary bladder of a postmenopausal woman. To the best of our knowledge, such a neoplasm has not yet been reported in the literature.