Atypical lipomas of the colon. Report of two cases with pseudomalignant features

Two cases of large intestinal submucosal lipomas with atypical features are described. These atypical features consist of cellular fibrosis, atypical hyperchromatic nuclei, and increased mitotic activity, with the occasional presence of atypical mitoses. They were associated with ulceration and appeared to be reactive in nature. The major importance lies in distinguishing these lesions from truly sarcomatous tumors.