Posttraumatic lipomas: where do they really come from?

A series of nine patients is reported in which a subcutaneous lipoma appeared within a few months after a blunt trauma. Computerized tomography and/or nuclear magnetic resonance and/or echography were employed for the diagnosis in addition to physical examination. Surgical removal of the masses was then performed without any recurrence at the 3-year minimum follow-up. In four cases, suction-assisted lipectomy was employed to minimize the scarring. However, in these cases a biopsy was first performed to rule out malignancy. The pathogenetic mechanisms of posttraumatic lipomas are reviewed in the literature and are found to be incompatible with some of the cases presented. Instead, the hypothesis of a true adipose tissue neoformation following trauma is suggested.