Multiple Myeloma Quiz

Multiple Myeloma: Practice Guide for Exam-Style Questions

Multiple myeloma is a hematologic malignancy characterized by the clonal proliferation of plasma cells in the bone marrow. Mastering its key features—from diagnostic criteria to treatment principles—is essential for clinical exams. This guide breaks down the core concepts into manageable sections to aid your review.

Decoding the CRAB Criteria for End-Organ Damage

The CRAB criteria are a critical mnemonic for identifying symptomatic multiple myeloma requiring treatment. Test questions often hinge on distinguishing these features from the asymptomatic precursor states.

• C – Hypercalcemia (serum calcium >11 mg/dL)
• R – Renal insufficiency (creatinine >2 mg/dL or clearance <40 mL/min)
• A – Anemia (hemoglobin <10 g/dL or >2 g/dL below normal)
• B – Bone lesions (one or more osteolytic lesions on imaging)

The Central Role of Malignant Plasma Cells

At its core, myeloma is a cancer of plasma cells. These abnormal cells accumulate in the bone marrow, crowding out normal hematopoietic cells and producing a massive amount of a single, non-functional antibody known as a monoclonal protein or M-protein.

Identifying the Monoclonal (M) Protein

The M-protein is the disease’s key biomarker. It is detected via serum protein electrophoresis (SPEP), which shows a sharp peak, or “M-spike,” in the gamma globulin region. This is a classic finding and a frequent topic in exam questions.

Key Diagnostic Tests: SPEP, UPEP, and FLC Assay

A comprehensive diagnostic workup is necessary to confirm myeloma and assess its severity. Be prepared to interpret results from these essential tests.

• Serum Protein Electrophoresis (SPEP): Detects and quantifies the M-spike in the blood.
• Urine Protein Electrophoresis (UPEP): Detects monoclonal free light chains in the urine (Bence-Jones protein).
• Serum Free Light Chain (FLC) Assay: Measures kappa and lambda light chains in the blood; an abnormal ratio is highly indicative of a clonal process.
• Bone Marrow Biopsy: Confirms the presence of clonal plasma cells (typically >10%).
• Skeletal Imaging: Identifies lytic bone lesions, a hallmark of active disease.

Understanding Bone Disease and Lytic Lesions

Myeloma cells disrupt the normal balance of bone remodeling by activating osteoclasts (bone-destroying cells) and inhibiting osteoblasts (bone-building cells). This leads to the characteristic “punched-out” lytic lesions, increasing the risk of pathologic fractures and hypercalcemia.

Standard First-Line Treatment Approaches

For transplant-eligible patients, induction therapy commonly involves a triplet regimen like VRd (Bortezomib, Lenalidomide, Dexamethasone), followed by an autologous stem cell transplant. Bisphosphonates are also used to manage and prevent skeletal-related events.

Differentiating Active Myeloma from Precursor Conditions

It is crucial to distinguish active myeloma from its asymptomatic precursors, Monoclonal Gammopathy of Undetermined Significance (MGUS) and Smoldering Multiple Myeloma (SMM). Treatment is initiated only when there is evidence of end-organ damage (CRAB criteria).

Common Complications Beyond Bone Pain

While bone disease is a central feature, myeloma’s systemic effects cause other significant complications. Be aware of these common clinical presentations, as they often appear in case vignettes.

Key Takeaways

• Myeloma is a malignancy of plasma cells producing a monoclonal (M) protein.
• The CRAB criteria (Hypercalcemia, Renal failure, Anemia, Bone lesions) define symptomatic disease.
• SPEP and bone marrow biopsy are essential for diagnosis.
• Bone disease results from increased osteoclast activity, leading to lytic lesions.
• Treatment is reserved for active myeloma, not asymptomatic precursor states like MGUS or SMM.

Frequently Asked Questions

This content is for informational and educational purposes only. It does not constitute medical advice. The information provided is intended to supplement, not replace, the knowledge and judgment of a qualified healthcare professional. Always consult a professional for diagnosis and treatment.