Dermatology Practical & Conceptual

A 56-year-old Caucasian male with a history of uncontrolled diabetes mellitus and multiple other comorbidities was evaluated for slowly expanding plaques of his right lower leg, left forearm and left dorsal hand that had been present for the past six years. The patient denied any associated pruritus or pain. There was no history of previous trauma, immunosuppression, recent travel or prior treatment of the areas. His most recent laboratory values were significant for a hemoglobin A1c (HbA1c) of 8.9%. Physical examination revealed annular waxy brown plaques with central atrophy and a lilac colored advancing edge located on the left posteriorlateral calf measuring 5 x 4 cm (Figure 1), left dorsal hand 5 x 3.5 cm and left forearm 11 x 9 cm. Interestingly, a 5.5 x 4.5 cm plaque on the right anterior lower leg exhibited central hyperkeratosis as opposed to atrophy (Figure 2). A punch biopsy of the atrophic plaque on the left forearm was performed, which revealed granulomatous inflammation with epithelioid granulomas and plasma cells. Periodic acid-Schiff, Gomori’s methenamine silver, acid-fast bacteria and Fite stains were negative for organisms. A subsequent biopsy of an adjacent area demonstrated an attenuated epidermis with diffuse and palisaded granulomatous inflammation within the deeper levels of the dermis (Figure 3). The inflammatory infiltrate was composed of lymphocytes and histiocytes, admixed with scattered perivascular plasma cells (Figure 4). There was minimal increase in interstitial mucin. Bacterial, fungal and acid-fast bacteria cultures for the second biopsy remained negative. The diagnosis is that of necrobiosis lipoidica (NL). The lesions were treated with topical emollients and clobetasol ointment once daily. After one month of treatment the patient reported improved appearHyperkeratotic necrobiosis lipoidica