Abstract

Necrobiosis lipoidica (NL) is a rare skin condition, typically presents at pretibial surface as dull red papule/plaque with elevated violaceous rim. Salient histological findings are in lower dermis with a layered inflammatory process, palisaded granuloma formation comprising of histiocytes, lymphocytes, plasma cells, and eosinophils, admixed with patches of collagen degeneration. The true cause remains unknown but is often associated with autoimmune disease, diabetes, and hyperlipidemia. We report a case of NL secondary to sclerotherapy. A 56-year-female who presented with erythematous papules on the back of her both knees in the area where she received sclerotherapy injections. She had no known relevant history and laboratory work-up was unrevealing. The rash was persistent with topical steroids. Punch biopsy from both sites revealed similar findings and showed interstitial granulomatous inflammation with giant cells centered in reticular dermis with extension into subcutaneous tissue, along with histiocytes, plasma cells and lymphocytes arranged around vessels and intercalating between collagen bundles with minimal epidermal changes. Colloidal iron showed a mild increase in dermal mucin. Special stains for microorganisms were negative. These histologic findings were reminiscent of an interstitial granulomatous dermatitis resembling NL/granuloma annulare (NL/GA). Given the presence of these lesions in the area of sclerotherapy injections and no evidence of any autoimmune disease or diabetes, the histologic findings most likely represent a type of hypersensitivity/foreign body reaction secondary to sclerotherapy. This histologic pattern resembling NL/GA associated with sclerotherapy has not been reported previously and adds sclerotherapy to the list of causes that can present with dermal findings resembling NL.