Multiple Myeloma and Plasma Cell Disorders

Multiple Myeloma and Plasma Cell Disorders

Multiple Myeloma and Plasma Cell Disorders

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Multiple Myeloma: The Basics - Plasma Cell Proliferation

  • Malignant neoplastic proliferation of monoclonal plasma cells, primarily in bone marrow.
  • Derived from post-germinal center B-cells.
  • Secretes monoclonal immunoglobulin (M-protein/paraprotein).
    • Most common: IgG (~55%), IgA (~20%).
    • Light chains only (Bence Jones protein in urine) in ~20% of cases.
  • Pathogenesis involves complex genetic abnormalities and bone marrow microenvironment interactions. Multiple Myeloma: Bone Marrow and Plasma Cells

⭐ Rouleaux formation (RBCs stacked like coins) on peripheral smear is a characteristic finding due to ↑ serum proteins (M-protein).

Clinical & Lab Clues - CRAB's Sinister Signs

📌 CRAB Criteria (myeloma-defining organ damage):

  • Calcium: Serum Ca > 11 mg/dL or > 1 mg/dL above ULN.
  • Renal: S.Cr > 2 mg/dL or CrCl < 40 mL/min.
  • Anemia: Hb < 10 g/dL or > 2 g/dL below normal.
  • Bone: ≥1 lytic lesions on imaging (X-ray, CT, PET-CT).

Other symptoms: Most common: bone pain (back/ribs); also pathological fractures, fatigue, recurrent infections. Initial lab clues: ↑ ESR, ↑ total protein (globulin gap). Plasma cell and rouleaux formation in multiple myeloma Diagnostic pointers:

  • SPEP: M-protein (IgG > IgA)
  • UPEP: Bence Jones proteinuria
  • SFLC assay: Abnormal κ/λ ratio

⭐ Hypercalcemia can cause confusion, constipation, and cardiac arrhythmias; it's a common oncologic emergency in MM patients.

Diagnosis & Staging - Nailing the Diagnosis

  • IMWG Criteria for MM:
    • Clonal BM plasma cells ≥10% / Plasmacytoma.
    • AND ≥1 MDE (Myeloma Defining Event):
      • 📌 CRAB: Ca >11mg/dL, Renal (CrCl<40ml/min), Anemia (Hb<10g/dL), Bone (≥1 lytic lesion).
      • SLiM: Sixty (≥60%) BM plasma cells, Light chain (FLC) ratio ≥100, MRI >1 focal lesion (≥5mm).
  • SMM (Smoldering Multiple Myeloma): M-protein (e.g., Serum IgG ≥3g/dL) AND/OR BM plasma cells 10-59%, with NO MDEs.

⭐ Rouleaux formation on peripheral smear: classic (non-specific) finding in MM due to ↑ paraproteins.

Staging (ISS & R-ISS):

StageISS CriteriaR-ISS Criteria (ISS + CG + LDH)
Iβ2M <3.5 & Alb ≥3.5ISS I & Std-risk CG & Normal LDH
IINot I or IIINot R-ISS I or III
IIIβ2M ≥5.5ISS III & (High-risk CG OR High LDH)

MM Management - Battling the Burden

  • Goal: Prolong survival, control disease, improve quality of life (QoL).
  • Treatment Approach: Risk-stratified; based on Autologous Stem Cell Transplant (ASCT) eligibility.
  • Key Drug Classes & Examples:
    • Proteasome Inhibitors (PIs): Bortezomib (📌 watch for neuropathy), Carfilzomib.
    • Immunomodulatory Drugs (IMiDs): Lenalidomide (📌 for maintenance), Pomalidomide.
    • Monoclonal Antibodies (mAbs): Daratumumab (anti-CD38).
    • Alkylating agents: Melphalan (ASCT), Cyclophosphamide.
  • Supportive Care Essentials:
    • Bisphosphonates (e.g., Zoledronic acid) for bone protection.
    • Manage: Anemia (ESA/transfusion), Infections (prophylaxis), Renal failure, Hypercalcemia.
    • VTE prophylaxis (especially with IMiDs).

⭐ Bortezomib, a proteasome inhibitor, is a cornerstone of MM therapy; peripheral neuropathy is a notable side effect.

Other Plasma Cell Players - MGUS & Waldenström's Glimpse

FeatureMGUSSMMMMWM
M-Protein< 3 g/dL3 g/dL (IgG/A) or urine ≥ 0.5 g/24hAny (IgG/A)IgM (any)
BMPC (%)< 10%10-60%10% /Plasmacytoma10% (LPL)
CRAB/SymptomsNoNoYes (CRAB)Hyperviscosity, neuropathy
Key DistinctionAsymptomatic↑ MM risk, asymptomaticCRAB+IgM, LPL, hyperviscosity

High‑Yield Points - ⚡ Biggest Takeaways

  • Multiple Myeloma: Plasma cell dyscrasia with CRAB criteria (HyperCalcemia, Renal failure, Anemia, Bone lesions).
  • Hallmark: Monoclonal M-protein (IgG > IgA) in serum/urine; Bence Jones proteinuria (light chains).
  • Diagnosis: >10% clonal plasma cells in bone marrow; peripheral smear shows Rouleaux formation.
  • MGUS (Monoclonal Gammopathy of Undetermined Significance): Precursor; M-protein <3 g/dL, <10% marrow plasma cells, no CRAB.
  • Waldenström's Macroglobulinemia: IgM hypersecretion, hyperviscosity, lymphadenopathy, no lytic bone lesions.
  • Key complications: Infections, renal failure, amyloidosis, pathological fractures.

Practice Questions: Multiple Myeloma and Plasma Cell Disorders

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Which among the following statements is wrong?

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Flashcards: Multiple Myeloma and Plasma Cell Disorders

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The most common symptom in multiple myeloma is _____.

TAP TO REVEAL ANSWER

The most common symptom in multiple myeloma is _____.

bone pain

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