TUMORS ARISING IN THE MUSCULARIS MUCOSAE OF THE SIGMOID COLON AND RECTUM

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 origin ating in muscularis mucosae or in the vascular system are uncommon. Tw o hundred rectal leiomyomas and leiomyosarcomas have been described. T umours originated in the muscularis mucosae are polypoid, pedunculated , benign and most of them will be treated by a polypectomy without rec urrence. However leiomyomas arising from the muscularis propia have a 60% of recurrence after local treatment and in some cases the recurren ce will be as a metastatic leiomyosarcoma. Three tumours arising from muscularis mucosae of the rectum and sigma are presented. All three we re diagnosed and removed by colonoscopy. Two were diagnosed as leiomyo mas. The third was a low grade leiomyosarcoma and an anterior resectio n was performed as definitive treatment.