A case of sarcoidal type of necrobiosis lipoidica

Abstract

Necrobiosis lipoidica (NL) is an idiopathic disorder usually presented with sharply demarcated yellowish to brownish patch on the extensor surface of lower legs. Histologically, it was characterized by palisading necrobiotic granuloma with a surrounding infiltrate of lymphocytes and histiocytes. Sarcoidal type of NL was a rare histologic variant of NL and it was characterized by a naked epithelioid granuloma with minimal necrobiosis. A 53-year-old woman presented with a 2-year history of confluented brownish macules and patches with yellowish crust and ulceration in both lower leg. Skin lesions were distributed dominantly on the extensor surface of lower legs. She did not complain of any subjective symptoms and did not have any underlying disease including diabetes mellitus. Histologic evaluation from macular lesion and crusted lesion of right lower leg showed mild hyperkeratosis, loss of rete ridge and palisading granuloma parallel to epidermis from upper dermis to subcutaneous layer. Granuloma was composed of epithelioid cells with multinucleated giant cell, few lymphocyte and central necrobiosis and reticulum stain revealed a few reticulum fibers surrounding the granulomas, which was consistent with histologic features of granuloma in sarcoidosis. Chest X-ray and serum angiotensin converting enzyme (47 U/mL) showed nonspecific findings, which suggested no evidence of systemic sarcoidosis. From these findings, she was diagnosed with sarcoidal type of NL and the skin lesion showed improvement with systemic steroid. Herein, we report an interesting case of sarcoidal type of NL, which has rarely been reported in dermatologic literatures.