Multiple Myeloma Mimicking a Small Vessel Vasculitis Presentation.

Multiple myeloma can have different clinical manifestations, and not all patients present with classic CRAB component. We describe a 46-year-old woman admitted to our hospital with a complaint of a bluish-to-black discoloration of the second toe that was rapidly progressive and acute kidney injury. We documented a Kappa light chain monoclonal gammopathy, increased presence of plasmacytes in bone marrow aspiration, and multiple lytic bone lesions, which led to a diagnosis of multiple myeloma. Although multiple myeloma presenting with blue finger syndrome is uncommon, it must always be considered as a differential diagnosis with this clinical finding.