Undifferentiated carcinoma of the large intestine.

Eight cases of the rare undifferented carcinoma of the large intestine are described. The histological distinction between undifferentiated and poorly differentiated colonic adenocarcinoma and malignant carcinoid is discussed. It is concluded that undifferented carcinoma is a variant of adenocarcinoma which tends to grow to a large size before symptoms are produced but which nevertheless has a good prognosis when locally resectable. Five patients survived between 6 and 28 years, one is well 6 months after operation and two cases where local removal could not be achieved, died within a year.