[Rectal malignant stromal tumor (leiomyosarcoma): echoendoscopic, computed tomographic aspects and anatomopathologic correlations]

We report the CT and endorectal us features of a malignant stromal tumor of the rectum (leiomyosarcoma). On CT scan, rectal leiomyosarcoma appeared as a large soft tissue mass, arising from the anterior rectal wall with exorectal extension. On endorectal US, the rectal leiomyosarcoma presented as a well-defined hypoechogenic and heterogeneous mass arising from the rectal muscularis propria. The uncommon location of leiomyosarcoma to the rectum may simulate other rectal tumors such as adenocarcinoma on CT. As suggested by this report, endorectal us demonstrated the muscular origin of the tumor.