LAUSR

Abstract Background: Lipomas are common benign soft tissue tumors that are well-circumscribed and encapsulated. However, adipose masses that are not demarcated from the surrounding fat are often encountered. Two distinct types of lipomas were analyzed from surgical perspective. Methods: Thirty patients were enrolled after lipoma excision and diagnosed with either encapsulated (n = 20) or non-encapsulated lipoma (n = 10). Comparison of clinical variables, histologic analyses and characterization of the lipoma adipose-derived stem cells (ASCs) between the two lipomas were performed. Results: Non-encapsulated lipomas were associated with older age at operation, larger tumor and increased seroma formation. The density of lymphatic vessels and gene expressions related to lymphatic vessel, inflammation and proliferation were increased in non-encapsulated lipoma. ASCs of non-encapsulated lipoma showed enhanced proliferation when cultured with serum. Conclusions: Non-encapsulated lipomas and their ASCs showed distinct lymphatic histology and cellular response. These findings elucidated the pathogenesis and pathophysiology of lipomas.