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PET/CT in lymphoma and the Deauville scale
In FDG-avid lymphomas (Hodgkin and most aggressive non-Hodgkin lymphomas), PET/CT is the central staging and response study, and response is measured on the 5-point Deauville scale, which compares residual uptake with uptake in the mediastinum and liver.
Why it matters in the exam
The exam asks to interpret a Deauville result, when a bone marrow biopsy is needed, and what new diffuse uptake after treatment means. The scale: 1 — no uptake; 2 — uptake up to the mediastinum (blood pool); 3 — above the mediastinum and up to the liver; 4 — moderately above the liver; 5 — markedly above the liver (roughly 2–3 times) or new lesions. Deauville 1–3 at end of treatment is a complete metabolic response; 4–5 with a fall from baseline is a partial response, and with no change or a rise — stable or progressive disease.
Under the Lugano criteria, in Hodgkin lymphoma and diffuse large B-cell lymphoma (DLBCL) a routine bone marrow biopsy is not needed when PET/CT is done, because focal marrow uptake indicates involvement; a biopsy is still considered in DLBCL when PET is negative and a suspected indolent marrow component would change treatment. In lymphomas with variable FDG avidity (marginal zone, small lymphocytic) PET is less useful. In follicular lymphoma a single focus with a very high SUV raises suspicion of transformation, and in chronic lymphocytic leukaemia high uptake directs biopsy for suspected Richter syndrome — transformation to DLBCL.
Pitfalls: diffuse marrow and spleen uptake after G-CSF, an active thymus after chemotherapy, and inflammation after radiation. Under immunotherapy (PD-1 antibodies, CAR-T) lesions may grow temporarily because of immune cell infiltration ("flare"), so the LYRIC criteria add an indeterminate response category that requires a repeat study before progression is declared. Interim PET after 2 cycles in Hodgkin lymphoma guides escalation or de-escalation of treatment.
Key points
- The Deauville scale compares the residue with the mediastinum and liver.
- Deauville 1–3 at end of treatment — complete metabolic response.
- In Hodgkin and DLBCL routine bone marrow biopsy is not needed.
- A very hot focus in CLL — suspect Richter.
- Under immunotherapy — indeterminate response and repeat study.
Summary table
| Deauville score | Residual uptake | End-of-treatment meaning |
|---|---|---|
| 1 | No uptake | Complete metabolic response |
| 2 | Up to the mediastinum | Complete metabolic response |
| 3 | Above the mediastinum and up to the liver | Usually complete response |
| 4 | Moderately above the liver | Partial response or residual disease |
| 5 | Markedly above the liver or new lesions | Residual or progressive disease |
Free exam questions
מהי ההגדרה המתאימה ביותר לטרנספורמציה(התמרה )על שם ריכטר (RICHTER) ? (the question as examined, in Hebrew)
- א. התמרה של CLL ל DLBCL
- ב. התמרה של Plasmacytoma ל- Myeloma
- ג. התמרה של High Grade Lymphoma ל - Low Grade
- ד. התמרה של Hodgkin’s Lymphoma ל- Non Hodgkin Lymphoma
לפניך FDG PET/CT של נבדק הנמצא במעקב בשל גמופתיה ( GAMMOPATHY .)איזה אבחנה מתאימה ביותר לממצאים בבדיקה ? (the question as examined, in Hebrew)
- א. MGUS
- ב. PLASMACYTOMA
- ג. SMOLDERING MYELOMA
- ד. PRIMARY LYMPHOMA OF BONE
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Sources
- Lugano Classification for Staging and Response Assessment of Hodgkin and Non-Hodgkin Lymphoma, 2014 — PET-CT staging and the five-point scale
- LYRIC: Lymphoma Response to Immunomodulatory Therapy Criteria, 2016 — Indeterminate response
- NCCN Guidelines: B-Cell Lymphomas and Hodgkin Lymphoma, 2025 — Role of PET-CT and bone marrow biopsy
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.