Necrobiosis lipoidica with superimposed pyoderma vegetans.

Necrobiosis lipoidica (NL) is a granulomatous inflammatory skin disease strongly associated with diabetes mellitus (DM). Red-brown papules expanding into plaques with erythematous indurated borders on the lower extremities are characteristic of NL. Diagnosis is made clinically; however, biopsy of lesions confirms the diagnosis. Untreated NL may ulcerate and lead to further complications, but progression to superimposed pyoderma vegetans (PV) is not a known occurrence.