Sclerotic lipoma: lipomas simulating sclerotic fibroma

We report a series of five unusual subcutaneous lipomas characterized by prominent stromal sclerosis in a storiform arrangement.

All lesions occurred in young male adults (23.0 +/- 9.5 years), three lesions were on the scalp and two on the hands. Clinically, lipoma, chondroma or some form of cyst were suspected. In contrast to sclerotic fibroma ('circumscribed storiform collagenoma') a variable number of adipocytes were interspersed within the fibrosclerotic background. These cells also showed immunoreactivity for S100 protein as well as intracytoplasmic lipid deposits ultrastructurally. None of the lesions recurred within a follow-up period of between 0.5 and 9 years.

Our series suggests that sclerotic lipomas should be classified with fibro- and myxolipomas, angiolipomas, spindle cell and pleomorphic lipomas, as an additional characteristic subtype of lipoma. Sclerotic lipomas are often misdiagnosed as a sclerotic fibroma, but are essentially fatty tumours and are, at least in our small series, not associated with Cowden's disease.