[Localized primary cutaneous nodular amyloidosis in a patient with paraproteinemia].

The term primary cutaneous amyloidosis (PCA) refers to a group of diseases caused by the extracellular deposition of amyloid in the skin without the involvement of other organs. PCA has been divided into the following types: macular, lichen and nodular. The first 2 types are characterized by the deposition in the papillary dermis of amyloid derived from the degeneration of keratin filaments. Primary localized cutaneous nodular amyloidosis (PLCNA) is the rarest form of PCA and the only one in which the amyloid deposits are of the amyloid light-chain (AL) type, as in the primary and myeloma-associated systemic forms of amyloidosis. AL amyloidosis is due to monoclonal immunoglobulin (Ig) lightchain deposition. We report the case of an 83-year-old man with a history of systemic hypertension, type 2 diabetes mellitus, and hyperuricemia, who was seen for a 2-year history of asymptomatic but progressive lesions that had appeared on the left lower limb. One year before consultation, he had been diagnosed with monoclonal gammopathy of undetermined significance (MGUS), after detecting an IgG( ) paraprotein in the serum with no evidence of multiple myeloma in the bone marrow study. Physical examination revealed a plaque with an area of ecchymotic appearance and several hard, reddish-orange nodules with an ulcerated surface in the pretibial region of the left leg (Fig. 1). Histopathological examination showed deposits of an amorphous eosinophilic material diffusely distributed