Fat tissue after lipolysis of lipomas:: A histopathological and immunohistochemical study

Background: Injections with Lipostabil (R), a phosphatidylcholine (PDC) containing substance, have become a popular technique to treat localized fat accumulation and lipomas for aesthetic reasons. Despite its frequent use, the mechanism of action of PDC and histological changes of treated fat tissue still remain unclear. To investigate the histological changes of lipomas after treatment with PDC. Methods: In all, fourteen lipomas (n = 14) in five patients presenting with multiple lipomas were treated with intralesional injections of PDC (Lipostabil (R), Nettermann, Germany). Histological changes with immunohistochemical analysis of the inflammatory process were evaluated 4, 10, 24, 48 h, 10 days, 30 days and 60 days after lipolysis. Results: Between 4 and 48 h after injection, histology shows a lobular neutrophilic infiltrate with partially destroyed fat cells. At day 10 the inflammatory process is accompanied by an infiltration of T-lymphocytes. After 60 days formation of macrophages with foam cells are visible, accompanied by thickened septa and capsula. Conclusion: Lipolysis with PDC results in a distinct inflammatory reaction of affected fat tissue, similar to factitial panniculitis. Early destruction of fat cells may suggest the involvement of detergent or osmotic mechanisms in the process.