Recommended Screening Modality for Lymphoma
PET-CT is the gold standard for screening and staging of FDG-avid lymphomas, including Hodgkin lymphoma and most non-Hodgkin lymphomas. 1
Initial Diagnostic Approach
- PET-CT is superior to conventional CT for detecting both nodal and extranodal disease sites in lymphoma, leading to more accurate staging 1
- For FDG-avid lymphomas (Hodgkin lymphoma, diffuse large B-cell lymphoma, follicular lymphoma), PET-CT should be the primary imaging modality 1, 2
- For variably FDG-avid lymphomas (such as marginal zone lymphomas), PET-CT is recommended at baseline and can be used for follow-up if the initial scan shows FDG avidity 2
- Only small lymphocytic lymphoma/chronic lymphocytic leukemia should exclusively undergo CT at baseline and follow-up, unless transformation to high-grade lymphoma is suspected 2
Specific Recommendations by Lymphoma Type
Hodgkin Lymphoma
- PET-CT is mandatory for accurate staging 1
- PET-CT can replace bone marrow biopsy in Hodgkin lymphoma as it is more sensitive for detecting bone marrow involvement 1
- Interim PET assessment during treatment may identify poor-risk patients, though treatment modification based on interim PET should be limited to clinical trials 1
Diffuse Large B-Cell Lymphoma (DLBCL)
- PET-CT is strongly recommended for initial staging and treatment response evaluation 1
- PET-CT leads to more accurate staging than CT alone, with stage changes in 10-30% of patients 1
- Combined PET-CT has been shown to obviate the need for additional diagnostic contrast-enhanced CT scans 3
Follicular Lymphoma
- PET-CT is recommended for routine staging 1
- PET-CT is mandatory to confirm localized stage I/II disease before involved-site radiotherapy (ISRT) 1
T-Cell Lymphomas
- PET-CT scan and/or chest/abdominal/pelvic CT with contrast of diagnostic quality are essential during workup 1
Practical Implementation
- The 5-point Deauville scale should be used for PET-CT response assessment in FDG-avid lymphomas 1, 2
- Complete metabolic response on PET-CT, even with a persistent mass, is considered a complete remission 1
- Routine surveillance scans after achieving remission are discouraged, especially for DLBCL and Hodgkin lymphoma 1, 4
- Judicious use of follow-up scans may be considered in indolent lymphomas with residual intra-abdominal or retroperitoneal disease 1
Additional Diagnostic Workup
- Excisional or incisional lymph node biopsy is preferred for initial diagnosis; core needle biopsy may be considered when excisional biopsy is not possible 1
- Complete blood count, routine blood chemistry including LDH, β2-microglobulin, and screening for HIV, HBV, and HCV are required 1
- Bone marrow biopsy remains important for many non-Hodgkin lymphomas, even with PET-CT imaging 1, 2
Common Pitfalls to Avoid
- False-positive rate with PET scans exceeds 20%, which can lead to unnecessary investigations, radiation exposure, biopsies, and patient anxiety 1
- Relying solely on CT for FDG-avid lymphomas may result in understaging and potentially suboptimal treatment 1, 3
- Performing both diagnostic CT and PET-CT concurrently provides minimal additional value and increases radiation exposure 3
- Routine surveillance imaging in remission patients has not been shown to improve survival outcomes and may lead to unnecessary procedures 1, 4
By following these evidence-based recommendations for lymphoma screening and staging, clinicians can ensure accurate disease assessment while minimizing unnecessary radiation exposure and procedures for patients.