[Necrobiotic xanthogranuloma with scleroatrophic lichen associated with paraproteinemia].

Necrobiotic xanthogranuloma (Xn) with paraproteinemia is a histiocytoxanthomatosis (non-X histiocytosis) that affects the dermis and subcutaneous tissue of the face and less frequently the trunk and limbs. We present the case of a 58-year-old woman with a previous background of IgG (lambda) paraproteinemia and multiple autoimmune diseases, that associate clinically and histologically typical lesions of Xn on face, neck and limbs and of lichen sclerosus et atrophius (LEA) on skin and mucosae. The treatments performed were ineffective, the Xn lesions followed a chronic and progressive course with increased number, size and ulceration of them. The paraproteinemia has remained stable since it was diagnosed eight years ago. We have not found the association of Xn with paraproteinemia and SAL described in the literature. We review the characteristics of this rare disease and its possible pathogenic mechanisms.