Light Chain Myeloma Precipitating Cryoglobulinemic Vasculitis.

Multiple Myeloma (MM) is characterized by monoclonal immunoglobulin production leading to widespread skeletal destruction and renal dysfunction. Light chain multiple myeloma (LCMM) affects 15% of individuals with MM and has an overall poor prognosis. Cutaneous manifestations are uncommon and it is rarely complicated by Type I Cryoglobulinemia (CG). Here we present an atypical case of κ-predominant LCMM complicated by Type I CG in an 80-year-old man who presented with a progressive non-blanching necrotic rash and ulcers involving his face, distal extremities, and oropharynx of two months duration prior to his admission at our facility. On admission to our facility, workup showed an overabundance of κ-light chains, elevated free κ/λ ratio, cryoglobulins, and an acute kidney injury. Marrow biopsy demonstrated 60% plasma cells with κ-light chain predominance. Cutaneous manifestations such as acral cyanosis and distal gangrene in LCMM indicate late stages of the disease, and such findings should raise suspicion for additional comorbid pathologies, including cryoglobulinemia, which could help direct earlier initiation of treatment.