[A Case of Lipoma Arising from the Mesentery Proper That Had Difficulty in Differential Diagnosis with Well-Differentiated Liposarcoma].

A 54-year-old male patient with a chief complaint of right lower abdominal pain and nausea visited the reporting hospital. Abdominal computed tomography was performed, which showed findings of a membrane-covered internally heterogeneous solid mass associated with a 11×10 cm well-circumscribed calcification, as well as ileus in the right lower abdomen. Based on the imaging findings, it was diagnosed with liposarcoma, and surgery was performed for both diagnosis and treatment. The mass was located in the mesentery of the terminal ileitis and could be removed without gross residue. Histopathological examination showed altered fat cells and fibrous partition, most of which were lipoma, but well-differentiated liposarcoma could also not be ruled out. It was diagnosed with lipoma mixed with well-differentiated liposarcoma. In particular, lipoma and liposarcoma from the mesentery proper is extremely rare. We encountered a case of lipoma arising from the mesentery proper that had difficulty in differential diagnosis with well-differentiated liposarcoma and here in report it with the addition of some literature consideration.