Necrobiosis lipoidica: clinical and immunofluorescent study.

Fourteen patients with necrobiosis lipoidica (NL) were carefully evaluated clinically and histologically. Ten of these patients (71%) had diabetes and most of them were treated with insulin (8 of 10 patients). Trauma was found as an immediate triggering factor in 6 patients (43%) and a possible preceding factor in 3 more cases. No immunoglobulins were found in the lesional skin of NL. Intradermal injections of histamine in healthy skin of legs led to deposition of immunoglobulins and complement (C3) in skin blood vessel walls in 4 of 12 patients studied (30%). These results suggest that immune complexes might be involved only in few cases of NL. Preceding trauma combined with metabolic and inflammatory changes could be an important triggering factor in the etiology of NL.