PA20.3 | Plasma Cell Dyscrasias (Multiple Myeloma) — Graded Quiz

A 68-year-old man presents with a 5-month history of worsening back pain, constitutional symptoms, and progressive renal impairment (creatinine 3.1 mg/dL). Haemoglobin is 8.8 g/dL (normocytic). Serum calcium is 12.4 mg/dL. Total protein is 11.2 g/dL with albumin of 2.9 g/dL. Urine dipstick protein is NEGATIVE. Skeletal X-ray shows multiple punched-out lytic lesions in the skull. Which single investigation will MOST efficiently establish the specific diagnosis?

A 65-year-old woman with known IgG-κ multiple myeloma complains of increasing bone pain and new-onset leg weakness. MRI spine reveals a T4 vertebral compression fracture with epidural soft tissue extending into the spinal canal. Which pathological mechanism MOST directly explains why myeloma causes purely lytic (not sclerotic) skeletal lesions?

A 70-year-old man with IgA-λ multiple myeloma presents with acute confusion, visual blurring, and epistaxis. His M-protein concentration is 6.8 g/dL. Serum viscosity is 6.2 cP (normal <1.8 cP). Fundoscopy shows dilated retinal veins with flame-shaped haemorrhages. Haematocrit is 28%. Urgent plasmapheresis is planned. While the apheresis team prepares, which IMMEDIATE bedside intervention should be performed first to temporarily reduce viscosity?

A 63-year-old man with newly diagnosed multiple myeloma has serum protein electrophoresis showing an M-spike in the gamma region. Immunofixation identifies the paraprotein as IgG-κ with concentration 4.8 g/dL. His haemoglobin is 7.6 g/dL and blood film shows marked rouleaux formation. Which mechanism MOST directly explains the rouleaux formation in his blood film?

A 67-year-old woman is found to have IgG-κ M-protein 0.9 g/dL on SPEP done for investigation of fatigue. Bone marrow biopsy shows 14% clonal plasma cells. She has no bone pain, no lytic lesions, haemoglobin 12.8 g/dL, calcium 9.2 mg/dL, and creatinine 0.9 mg/dL. Bone survey and MRI spine are normal. Which diagnosis is most appropriate and what is the MOST important management implication?

A 64-year-old man with myeloma presents with progressive breathlessness, orthostatic hypotension, and macroglossia (enlarged, firm tongue). He has bilateral ankle oedema. Serum creatinine is 2.1 mg/dL. Echocardiogram shows concentric left ventricular thickening with a 'granular sparkling' pattern and diastolic dysfunction. 24-hour urine shows 4.2 g of protein. Congo red staining of the rectal biopsy shows apple-green birefringence under polarised light. Which pathological process explains his systemic manifestations?

A 72-year-old woman with IgG myeloma on lenalidomide-dexamethasone therapy develops sudden onset severe lumbar pain after lifting a grocery bag. MRI shows an L3 vertebral compression fracture. Bone densitometry (DEXA) shows T-score −3.8 at the lumbar spine. Which combination of factors MOST directly explains her extreme skeletal fragility?

A 60-year-old man with IgA-λ myeloma develops a creatinine rise from 1.0 to 4.2 mg/dL over 6 weeks. His urine protein electrophoresis shows a dense Bence-Jones band (free lambda light chains). Renal biopsy shows large tubular casts that are hard, fractured, and contain both light chains and Tamm-Horsfall protein, with surrounding inflammatory giant cells. Which mechanism MOST directly explains his acute renal failure?

A 58-year-old woman with newly diagnosed IgG-κ multiple myeloma is being counselled on treatment. Her physician explains she will receive a proteasome inhibitor (bortezomib) as part of induction therapy. Which mechanism of action of bortezomib MOST directly explains its efficacy against plasma cell malignancies?

A 74-year-old man with a 2-year history of known MGUS (IgG-κ, 1.2 g/dL M-protein, 6% marrow plasma cells) presents with new onset severe back pain. Imaging reveals two new lytic vertebral lesions at T8 and L1. Repeat marrow biopsy shows 32% plasma cells. Haemoglobin is 9.1 g/dL, calcium 11.2 mg/dL, and creatinine 1.8 mg/dL. His serum beta-2 microglobulin is 5.8 mg/L and albumin is 2.8 g/dL. According to the Revised International Staging System (R-ISS), what prognostic stage applies?

A 66-year-old woman has a urine sample sent for investigation of suspected multiple myeloma. Standard urine dipstick shows NEGATIVE for protein. However, urine protein electrophoresis shows a large monoclonal spike in the fast gamma region later confirmed as free lambda light chains. Which property of Bence-Jones protein explains the false-negative urine dipstick result?

A 61-year-old man with IgG myeloma develops a fever of 39.5°C, cough, and hypoxia three weeks after starting a new treatment cycle. His absolute neutrophil count (ANC) is 0.4 × 10⁹/L. Chest X-ray shows bilateral ground-glass infiltrates. Blood cultures are pending. Which organism and risk factor MOST specifically contributes to his infection risk beyond the neutropenia itself?