RESUMEN
Necrobiotic xanthogranuloma (NXG) is a rare chronic condition, belonging to the group non-Langerhans cell histiocytoses, which is relevant due to the possibility of extracutaneous involvement and association with systemic diseases, particularly monoclonal gammopathy, MGUS and multiple myeloma. The case reported here NXG was diagnosed after 1 years of evolution in patient with asymptomatic multiple myeloma. After treatment with bortezomib, lenalidomid and dexamethasone, there was evident abrupt decrease of monoclonal immunoglobulin to not measurable level (complete remission of multiple myeloma) and in the same time was evident disappearance of cutaneous and hepatic lesions of NXG on FDG-PET/CT. The etiopathogenetic association of monoclonal immunoglobulin with NXG is documented in this case report with disappearance of NXG in the time of disappearance of monoclonal immunoglobulin.