The purpose of this article is to place on record 7 cases of malignant neoplasm of the rectum; 2 of spindle cell sarcoma, 1 of myosarcoma, 3 of melanoma and 1 of lymphosarcoma (leukosarcoma). We are including melanoma within this group of sarcomas notwithstanding the controversy as to whether these growths are of epithelial or of mesoblastic origin.
INCIDENCE
Sarcoma of the rectum, though well recognized and described, occurs infrequently. It has been estimated that only 0.5 per cent of all rectal neoplasms are sarcoma. Weeks1 estimated that 1 of each 242 sarcomas occurred in the rectum, Williams (quoted by Pennington2) 1 in 270 and Lapeyre3 1 in 216. Sarcoma occurs with less frequency in the rectum than in other portions of the gastro-intestinal tract. Pennington2 quoted Corner-Fairbanks that of 175 gastro-intestinal sarcomas only 11 were in the large bowel, 7 of these being in the