Nevus lipomatosus cutaneus superficialis. A light and electron microscopic study.

Nevus lipomatosus cutaneus superficialis is a rare idiopathic abnormality characterized by isolated dermal collections of adipose tissue. The lesions usually are either congenital or present by the third decade of life and occur predominantly in the pelvic-girdle area. We saw a case that was unusual because the nodules present arose in the patient's fifth decade of life and were confined to the abdominal wall. Histopathologic examination of the nodules showed mature adipose tissue, perivascular mononuclear cell infiltrates, and numerous mast cells. By electron microscopy, we observed small mature lipocytes within the perivascular mononuclear infiltrates. However, neither lipoblasts nor the transition of mesenchymal cells to lipocytes could be demonstrated.