Monoclonal gammopathy of undetermined significance

Case history

An otherwise healthy 49-year-old black man presents with a second sinusitis infection in 4 months. He has no significant medical history or current medications, and has no back pain or gastrointestinal or urinary symptoms. Physical exam is unremarkable. Splenomegaly and lymphadenopathy are absent, and cardiovascular and respiratory exams are normal. Routine laboratory results show a normal complete blood count, normal kidney and liver function, absent protein in the urine, and mildly increased total protein in serum chemistries. Serum protein electrophoresis shows an IgG monoclonal (M) protein of 2 g/dL.