Monoclonal gammopathy of clinical significance (MGCS) refers to disorders in which small B-cell or plasma-cell clones produce pathogenic monoclonal immunoglobulins that cause organ injury independent of tumor burden. Because the clinical spectrum is heterogeneous and diagnostic criteria remain evolving, MGCS is frequently underrecognized, particularly when organ manifestations precede detectable paraproteinemia. We report a 52-year-old man with multisystem manifestations including cutaneous xant