Over several years, brown plaques developed on the legs of a 59-year-old woman with diabetes mellitus and pulmonary sarcoidosis. The plaques were dry and cracked in the winter but otherwise asymptomatic. Physical examination revealed atrophic, red-brown to yellowish plaques with telangiectasia involving both legs.
The differential diagnosis included necrobiosis lipoidica, granuloma annulare, sarcoidosis, lupus erythematosus, and early lipodermatosclerosis.
Key Point: Biopsy revealed a granulomatous infiltrate of epithelioid histiocytes and multinucleated giant cells surrounded by lymphocytes “layered” throughout the dermis. Special stains and polarized microscopy did not reveal any microorganisms or foreign-body material. ANA, anti-dsDNA, and anti-SCL70 were negative. These findings were consistent with necrobiosis lipoidica (diabeticorum).
Treatment: The patient was treated with clobetasol proprionate 0.05% cream. She subsequently underwent bariatric surgery; after significant weight loss, her diabetes improved and no new plaques developed.
Necrobiosis lipoidica (diabeticorum) is a granulomatous dermatitis that affects fewer than 1% of diabetic patients and can rarely affect non-diabetic patients. The skin disease can present before, concurrent with, or after onset of diabetes; the progression of skin disease does not correlate with diabetes control or severity. Plaques are usually painless because of destruction of cutaneous nerves; however, the minority of patients may experience neuropathic pain. Ulceration may follow preceding trauma.
Note: Despite its atrophic surface change, necrobiosis lipoidica is a granulomatous dermatitis that commonly requires super-potent or intralesional corticosteroids for adequate treatment.