A 63-year-old woman had stage IIIb IgG κ multiple myeloma that contained a 13q deletion by fluorescence in situ hybridization. She was treated with vincristine, adriamycin, and dexamethasone, which achieved a partial response. Three months later, there was clinical and biological progression. Despite treatment with bortezomib and dexamethasone, a plasmacytoma developed in the right scapula. Further treatment included local radiotherapy followed by autologous peripheral blood stem cell transplantation (PBSCT).

Three months after transplantation, rose-colored nontender nodules appeared on the skin of the right arm. A skin biopsy showed a diffuse infiltrate of plasma cells in the dermis (shown, left) that were strongly immunoreactive for κ chain (shown, right). The patient died a few weeks later.

Although extramedullary relapses of myeloma are occasionally seen after PBSCT, skin involvement is a rare event.