20 Plasma Cell Disorders

Multiple Myeloma

• symptoms from Ig

• paraproteins: Ig produced in excess by MM

• either 2 k or 2 lambda

• heavy chain: IgG heavy chain makes IgG antibody

• antibody description: IgGk for k light chain. IgG-lambda for lambda light chain

• toxic to kidney

• deposit in tissues and form amyloid structures

Symptoms

• elderly with minor fall/fracture of vertebral column

• obstruction leads to renal failure

• detected by UPEP

• lower GFR > renal failure

• On light microscopy, numerous large, glassy casts that stain intensely eosinophilic are seen. Deposition of light chain fragments in the glomerular mesangium and capillary loops can also cause renal failure in MM (AL amyloidosis).

• bone marrow replaced by plasma cells: underproduction of RBC

Diagnosis

• gamma spike last spike

• MM: gamma fraction very large

• M spike: monoclonal production of Ig

• UPEP being replaced by this

• SPEP not good enough: other problems also produce monoclonal protein

MGUS

• no symptoms

Waldenstrom Macroglobulinemia

• IgM, not IgG, IgA, or light chains (MM)