Multiple Myeloma and Plasma Cell Disorders MCQs

Plasma cell myeloma (multiple myeloma) is characterized by a multifocal infiltration of malignant plasma cells in the bone marrow. There are typically multiple destructive lytic lesions or diffuse demineralization of bone. Major diagnostic criteria for plasma cell myeloma include marrow plasmacytosis (>10%), plasmacytoma on biopsy, and immunoglobulin paraprotein (M-component). Neoplastic cells typically secrete a homogeneous complete or partial immunoglobulin chain, which can be seen in serum or urine electrophoresis. In this patient, the neoplastic clone secretes excess kappa light chains. Reference: Robbins & Cotran Pathologic Basis of Diseases 10 th edition, Chapter 13, pg 616-618

The most frequent M protein produced by myeloma cells is IgG (60%), followed by IgA (20% - 25%); only rarely are IgM, IgD, or IgE M proteins observed. The plasma cells produce only κ or λ light chains. Because free light chains are small in size, they are also excreted in the urine, where they are referred to as Bence Jones proteins. Bence Jones proteins in the urine can be a diagnostic marker for multiple myeloma and are often used in laboratory tests to detect and monitor the disease. Reference :Robbins, 10th edition, page number - 472

Bony lesions are most common in vertebral column. The following is the ascending order of lesion to occur: Vertebral column> Ribs> Pelvis> Femur> Clavicle> Skull Reference:- Harrison, 16 th edition, page number - 659

Russel bodies, Mott bodies and Dutcher bodies are seen in Plasma cells and plasma cell associated disorder is Amyloidosis. Reference: Wintrobe 8th edition, page 789

Explanation: Serum electrophoresis showing IgG is the best diagnostic test for multiple myeloma . Detects monoclonal immunoglobulins (M-protein) produced by malignant plasma cells. Confirms clonality and quantifies abnormal proteins, aiding in diagnosis and monitoring. Multiple myeloma typically presents with: CRAB features: Hypercalcemia, Renal failure, Anaemia, Bone lesions Lytic bone lesions (punched-out lesions on skull X-ray) Elevated ESR and fatigue Explanation of Other Options: Serum CA 15-3 (Option B): Tumor marker primarily for breast cancer monitoring ; not diagnostic for myeloma. Whole-body scan (Option C): Useful to assess disease extent but not for initial diagnosis of multiple myeloma. CT head with contrast (Option D): Not indicated as first-line investigation Lytic lesions are better evaluated by X-ray or MRI if needed.

Cells may accumulate abnormal amounts of various substances, which may be harmless or may cause varying degrees of injury. The substance may be located in the cytoplasm, within organelles(typically lysosomes) or in the nucleus and it may be synthesized by the affected cells or it may be produced elsewhere. In multiple myeloma, the marked accumulation of newly synthesized immunoglobulins that may occur in the RER of some plasma cells, forming rounded, eosinophilic Russell bodies. Reference: Robbins and Cotran Pathologic Basis of Diseases, 10 th ed Pg:51