## Staging and Prognostic Assessment in Hodgkin Lymphoma ### Role of PET-CT in HL Staging **Key Point:** 18F-FDG PET-CT is the imaging modality of choice for staging and prognostic assessment in HL because: - High sensitivity (>90%) and specificity (>95%) for detecting nodal and extranodal disease - Identifies metabolically active (FDG-avid) lymph nodes regardless of size - Detects bone and bone marrow involvement (not visible on CT alone) - Guides treatment decisions (involved-field vs. extended-field radiation) - Provides prognostic information (SUVmax correlates with prognosis) ### PET-CT Advantages Over CT Alone | Feature | CT | PET-CT | |---------|----|---------| | Nodal size assessment | Yes (>1 cm) | Yes + metabolic activity | | Extranodal disease | Limited | Excellent (bone, marrow, organs) | | Splenomegaly assessment | Morphologic only | Functional (FDG uptake) | | Bone involvement | No | Yes (osteolytic/sclerotic) | | Prognostic value | Limited | High (SUVmax) | **High-Yield:** PET-CT is now standard of care for: 1. Initial staging (determines Ann Arbor stage) 2. Interim assessment (after 2 cycles of chemotherapy) 3. End-of-treatment assessment (confirms complete metabolic response) 4. Surveillance (detects early relapse) ### Deauville Score for Response Assessment **Mnemonic:** **DEAUVILLE** = Standardized scoring for PET response: - Score 1–2: Complete metabolic response (CMR) - Score 3: Uncertain response (requires clinical correlation) - Score 4–5: Partial metabolic response or progressive disease ### Why Other Investigations Are Outdated or Unnecessary **Warning:** Bone marrow biopsy is no longer routinely performed because: - PET-CT detects marrow involvement with high sensitivity - Invasive procedure with limited additional benefit - Not recommended in current staging algorithms (NCCN, ESMO) Diagnostic laparotomy with splenectomy is obsolete: - Surgical staging abandoned since 1980s–1990s - PET-CT replaced the need for invasive staging - Splenectomy increases infection risk (post-splenectomy sepsis) Gallium-67 scintigraphy: - Inferior sensitivity and specificity compared to PET-CT - Poor spatial resolution - Longer imaging time (48–72 hours post-injection) - Largely replaced by PET-CT in modern practice **Clinical Pearl:** Even in early-stage HL (stage I–II), PET-CT may reveal occult disease in 10–15% of patients, altering treatment strategy from radiation alone to combined modality therapy. 
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