Necrobiotic xanthogranuloma in IgG‐κ multiple myeloma

A 70-year-old woman with a 20-year history of immunoglobulin (Ig) G monoclonal gammopathy undetermined significance (MGUS) presented asymptomatic skin lesions on her face, chest and arms. These had begun five years earlier in the infraorbital area. Dermatological examination revealed yellow orange-red, soft, partially ulcerated plaques telangiectasia (images). Skin histology was consistent necrobiotic xanthogranuloma (NXG). Laboratory tests showed serum IgG paraprotein 2.97 g/l kappa free light chain 75.4 mg/l (normal range 3.3–19.4) kappa/lambda ratio 9.8. She also found to have low haemoglobin concentration (94 g/l) mild hypercalcaemia (2.89 mmol/l), while β2 microglobulin, albumin creatinine were within normal limits. Total body computed tomography no osteolytic lesions. Clonal plasma cells bone marrow greater than 10% diagnosis symptomatic IgG-κ multiple myeloma (stage I) made. The patient treated VMP (bortezomib, melphalan prednisone) neither haematological nor cutaneous response. Necrobiotic (NXG) is non-Langerhans cell histiocytosis. It chronic slowly progressive dermatosis primarily affecting may involve eye internal organs, including gastrointestinal respiratory tracts. In vast majority cases, made patients under surveillance for MGUS, particularly subtype. Conversely, more rarely associated condition generally occurs after NXG onset. Chemotherapy NXG-associated malignancies does not always lead improvement. Intravenous immunoglobulin, antimalarials lenalidomide/thalidomide be therapeutic options.