Livedo Reticularis due to Cryoglobulinemia Associated with Monoclonal Gammopathy of Undetermined Significance

A 76-year-old man was referred to us for the evaluation of a 6-month history of violaceous erythema with itching in the bilateral lower extremities. Physical examination showed livedo reticularis on the lower extremities with multiple ulcers on the ankles and the toes. Laboratory investigations revealed elevated levels of'M'protein, which was positive for the cryoglobulin test in serum. The cryoglobulin was later identified as the IgG-λ, IgM-κ class, which is the same as the 'M' paraprotein found in serum. This finding established monoclonal gammopathy of undetermined significance (MGUS) as the source of the cryoglobulinemia. This case highlights livedo reticularis as a cutaneous manifestation of MGUS-associated cryoglobulinemia.