|· A small number of healthy people have an abnormal protein (monoclonal protein or M protein) in their blood. Monoclonal gammopathy of undetermined significance (MGUS), is benign and usually causes no problems. On occasion, monoclonal gammopathy of undetermined significance progresses over decades to other disorders, including some forms of cancer.· Each monoclonal protein produced by a clone of plasma cells in the blood. Important to differentiate mono from polyclonal. Monoclonal protein has possible malignant origin; polyclonal increase has inflammatory or reactive process.· Presence of monoclonal protein (immunoglobulin G, A, or M), in the serum of pt with peripheral neuropathy raises suspicion of POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes), as well as multiple myeloma, macroglubulinemia, or lymphoma.
· Presence of M protein may also be benign-“monoclonal gammopathy of undetermined significance” or MGUS.
· Cause of peripheral neuropathy with monoclonal gammopathy is unknown. Genetics may play a role.
· Pathology: The IgM monoclonal protein with anti-MAG activity associated with peripheral neuropathy reacts or binds to the myelin sheaths. Loss of fibers, wallerian like degeneration, and segmental demyelination were found in the peroneal superficial nerve of a pt with an IgM monoclonal gammopathy and peripheral neuropathy.