Cutaneous Vasculitis: An Unusual Presentation of a Biclonal Nodal Plasma Cell Dyscrasia

Abstract

We describe an unusual case of a biclonal nodal plasma cell dyscrasia, presenting with a vasculitic rash, end-organ damage, and cytopenias. Serum protein electrophoresis demonstrated a biclonal kappa-restricted paraprotein, with a negative skeletal survey and no bone marrow disease. Fluorodeoxyglucose-PET-CT (FDG-PET-CT) revealed nodal involvement, which was not appreciable clinically, and facilitated biopsy, confirming the diagnosis of a nodal plasmacytoma. Complete biochemical response and resolution of the vasculitic rash were achieved with bortezomib-based therapy.

Figure 1

(a, b, c) Diagnostic axial FDG-PET images illustrate FDG-avid axillary, mediastinal, and cervical nodes, respectively. (c, d, f) Posttreatment axial PDG-PET images illustrate no FDG-avid evidence of residual disease at cervical, mediastinal, and axillary nodes, respectively.

Figure 2

Left axillary lymph node biopsy. (a) Haematoxylin and eosin stain at ×40. (b) CD138 stain at ×40, strongly positive. (c) Kappa stain at ×40, strongly positive. (d) Lambda stain at ×40, negative demonstrating kappa light chain restriction.