[Tumors originating in the muscularis mucosae of the recto-sigma]

Tumours arising from the muscular layer of the bowel are uncommon and extremely rare when localized in colon and rectum. Most of them arise from the external muscular layer or muscularis propria. Tumours originating in muscularis mucosae or in the vascular system are uncommon. Two hundred rectal leiomyomas and leiomyosarcomas have been described. Tumours originated in the muscularis mucosae are polypoid, pedunculated, benign and most of them will be treated by a polypectomy without recurrence. However leiomyomas arising from the muscularis propia have a 60% of recurrence after local treatment and in some cases the recurrence will be a metastatic leiomyosarcoma. Three tumours arising from muscularis mucosae of the rectum and sigma are presented. All three were diagnosed and removed by colonoscopy. Two were diagnosed as leiomyomas. The third was a low grade leiomyosarcoma and an anterior resection was performed as definitive treatment.