title: Solitary necrobiotic xanthogranuloma of an upper extremity in association with multiple myeloma.
abstract: Necrobiotic xanthogranuloma (NXG) is an uncommon granulomatous disorder of unknown pathogenesis that often presents with yellowish plaques in a periorbital distribution. While a majority of cases are associated with an underlying paraproteinemia of the IgG kappa type, a much smaller number are found to be associated with an underlying multiple myeloma. We present a case of a 78-year-old male with an isolated lesion of NXG on his right upper extremity. Following his diagnosis of NXG, further investigation for underlying systemic disorders with serum immunofixation revealed a monoclonal IgG kappa immunoglobulin with an M-spike of 1.2 g/dL. A PET-CT demonstrated bone destruction in the left proximal fifth rib, left scapula, the anterior lumbar I (L1) vertebrae, the left lumbar III (L3) vertebrae posterior elements and possibly left sacrum. A bone marrow biopsy revealed 18 % plasma cells. With these findings he was diagnosed with stage I multiple myeloma. Though clinically unimpressive and atypical in location for NXG, early biopsy and diagnosis of this solitary lesion led to the discovery of his hematopoietic disorder.
authors.forename: E Eugene
authors.initials: EE
authors.lastname: Bain
authors.forename: Shane A
authors.initials: SA
authors.lastname: Meehan
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Hale
mesh_terms: D000368:Aged; D001706:Biopsy; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D007145:Immunoglobulin kappa-Chains / Q000276:immunology; D008297:Male; D009101:Multiple Myeloma / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D058252:Necrobiotic Xanthogranuloma / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods; D034941:Upper Extremity
chemical_list: D007074:Immunoglobulin G; D007145:Immunoglobulin kappa-Chains