A 55-year-old male presents with renal failure, bone pain for 7 years and osteolytic lesions on X-ray. Serum electrophoresis shows M spike and 35% plasma cells with aberrant protein expression. What is the diagnosis? (E. REPEAT 2013)

Ref: Harrison 's Principles of Internal Medicine, 18th edition. Pages 937-942: CMDT 2013, Pages 527-529Explanation:MULTIPLE MYELOMAMalignant proliferation of plasma cells derived from a single clone.Clinical Featureso Lytic hone lesionso Anemia with high ESRo Rnulex formation of red cellso Renal failureo Infectionso Hypercalcemia.Classical Triad of MMo Marrow plasmacytosis >10%o Lytic bone lesionso Serum and/or urine M component.Diagnosiso Monoclonal plasma cells (k, l, light chain restricted) in BM or as a tumor (solitary plasmacytoma).o End organ damage--lytic bony lesions, anemia, hypercalcemia, renal failure with paraproteinemia (mostly IgG or IgA)o Serum electrophoresis for M band (b,g)o Urine Bence Jones protein for light chainso Non secretory myeloma--No paraproteins, poor prognosis.o X-rays axial skeleton--Skull, spine, long bones, ribs for lytic lesionso PET or MRI useful for early lesionso Radionuclide scan NOT useful.DD: Smoldering myeloma and MGUS.Treatment:o Thalidomide/lenolidamide + high dose dexamethasone.o Bortezomib.o Autologous hematopoietic SCT.o Localized RT tor vertebral collapse, o Bisphosphonates for malignant hypercalcemia (beware of osteonecrosis jaw!).* PrognosisStage32 microglobulinAlbuminSurvivalStage 1<3.5 mg/L>5.5 g/dL>5 yearsStage 23.5-5.5 mg/L Stage 3>5.5 mg/L <2 years Smouldering myeloma (Asymptomatic myeloma)MGUSM protein in serum> 30g/L<30g/LBM plasma cells> 10%< 10%SymptomsNil End organ damageNilNilPlasma Cell LeukemiaPlasma cells >2000/pL in 2% of patients.Seen in IgD (12% t and IgE (25%) myelomas.