In fact, some leiomyosarcomas of the urinary bladder can express cytokeratin and are partially or extensively myxoid to such a degree that distinction from IMTs may become impossible; albeit, the presence of (a) prominent cytological atypia, (b) abnormal mitotic figures, (c) preferential reactivity for high-molecular-weight caldesmon and the lack of (a) a delicate vascular network, (b) interspersed inflammatory and red blood cells, and (c) ALK-1 immunostaining (usually demonstrated in IMT) may be of particular value in the differential diagnosis [1,3-5,14,19,20]. This evidence concerns the gene CALD1 and inflammatory myofibroblastic tumor.