Contributor: Gordon K. Klintworth
Atypical lipoma (atypical lipomatous tumor, well-differentiated liposarcoma) is a tumor of adipose connective tissue with atypical histopathologic features, but which does not metastasize and which can be adequately treated by a local excision especially if it is situated superficially. When present in the retroperitoneum such lesions may be difficult to excise and recurrences follow attempts at surgical removal. An atypical lipoma needs to be differentiated from the various types of  liposarcoma.