Plasma cell dyscrasias are a heterogeneous group of disorders caused by the monoclonal proliferation of plasma cells in the bone marrow. Multiple myeloma is the most prevalent plasma cell dyscrasia and the second most frequent hematologic malignancy. Other plasma cell dyscrasias include monoclonal gammopathy of undetermined significance, solitary plasmacytoma, AL amyloidosis, POEMS syndrome, and heavy-chain diseases.