Eruptive ulcerative follicular spicules heralding progression of smouldering multiple myeloma

erein, we describe a patient with immunoglobulin G (IgG)-lambda smoldering multiple myeloma with translocation t(4:14) who developed widespread ulcerative horny-like spicules, heralding rapid progression to overt myeloma requiring aggressive chemotherapy and autologous stem cell transplantation. The serum abnormal immunoglobulin in the blood was cryoglobulin, which typically precipitates in the tissues at low temperatures causing inflammation and tissue damage. Histopathological changes, observed in lesions at different evolutionary stages, evidenced columns of horny-like eosinophilic homogeneous material, immunoreactive for IgG lambda, protruding from the dilated and/or distorted follicular openings or acrosyringia and small vessel thrombotic vasculopathy and vasculitis in concert with an inflammatory neutrophilic and lymphocytic reaction. Biochemical investigations on material from a spicule and ulcero-necrotic lesion revealed cryoprecipitates containing IgG-lambda with electrophoretic characteristics identical to those of the serum dysprotein. Our findings suggest that the formation of spicules and development of ulcerative lesions are a part of the same clinical spectrum where the cold-dependent precipitation of the immunogenic dysprotein, both in the skin vessels and hair follicle infundibula, play a major pathogenetic role. Whether this highly characteristic paraneoplastic dermatosis can identify patients with high-risk cytogenetic abnormalities and be incorporated into prognostic models, applicable early on in the course of myeloma, warrants further investigation. © 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.