Necrobiotic xanthogranuloma (NXG), is a rare multisystem disease that manifests as cutaneous inflammatory lesions, and is commonly associated with lymphoproliferative disease. Diffuse normolipemic plane xanthoma (NX), is also a rare, acquired disease that is often associated with systemic diseases such as lymphoproliferative disease. Both of these diseases have been reported to be associated with monoclonal gammopathy (MG). However, there are few cases in which these diseases co-exist. A 78-year-old female, who had a known case of NX on the neck and axillary area, presented with an asymptomatic erythematous plaque on her left supraclavicular area. Histopathological examination showed lymphoid aggregates, necrobiotic areas, and granulomatous inflammation in the dermis. Numerous foreignbody and Touton type giant cells were noticed. Serum protein immunoelectrophoresis showed an IgG kappa type MG. Lipid profile of the patient was normal. Bone marrow examination showed plasma cell myeloma. Based on these histologic and laboratory results, we diagnosed this lesion as NXG coexisting with NX and multiple myeloma. She was started on treatment with bortezomib and melphalan for multiple myeloma, and high-dose systemic corticosteroid and triamcinolone intralesional injection for the skin lesion. After 3 months of treatment, the NXG skin lesion and MG im-proved. (Ann Dermatol 32(1) 53∼56, 2020

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