A 58-year-old woman with newly diagnosed multiple myeloma (IgG-κ type, 35% bone marrow plasma cells) is being staged. Which investigation is most appropriate to assess for extramedullary disease and spinal involvement?

Explanation

## Staging Investigation for Multiple Myeloma: Detecting Extramedullary Disease **Key Point:** Whole-body low-dose CT (WBLD-CT) is the current standard imaging modality for staging multiple myeloma, superior to skeletal survey for detecting lytic lesions, extramedullary disease, and soft-tissue involvement. ### Evolution of Myeloma Imaging | Modality | Sensitivity for Lytic Lesions | Detects Extramedullary Disease | Detects Spinal Involvement | Current Role | |---|---|---|---|---| | Skeletal survey | ~60–70% | Poor | Moderate | Outdated; replaced by WBLD-CT | | WBLD-CT | >90% | Excellent | Excellent | **Standard for staging** | | MRI (whole-spine) | Excellent | Good | Excellent | For spinal cord compression assessment | | PET-CT | High specificity | Good | Good | Prognostic; not routine staging | **High-Yield:** WBLD-CT detects lytic lesions in ~90% of myeloma patients, compared to ~60% with skeletal survey. It is now the recommended first-line imaging for staging per IMWG and NCCN guidelines. **Clinical Pearl:** MRI of the spine is reserved for patients with neurologic symptoms (spinal cord compression, radiculopathy) or when WBLD-CT shows spinal lesions requiring further characterization. **Warning:** Skeletal survey is now considered outdated for myeloma staging; many centers have abandoned it in favor of WBLD-CT, though it may still be used in resource-limited settings. ### Extramedullary Disease (EMD) Detection WBLD-CT excels at identifying: - Soft-tissue masses adjacent to bone lesions - Lymph node involvement - Organ infiltration (liver, spleen, kidneys) - Extraosseous plasmacytomas **Mnemonic: WBLD-CT Advantages** — **W**hole-body coverage, **B**etter sensitivity (>90%), **L**ytic lesion detection, **D**etects extramedullary disease, **CT** = high resolution.