Lymphoma is a neoplasia of the lymphoid series in the lymphoid organs or extranodal tissue. Lymphoma has categories with overlapping features which has an impact on clinical features, natural history, prognosis and treatment.
Fig-1 showing the 2016 WHO classification of the lymphomas.
The 2016 revision of the WHO classification maintains the same principles of the 2008 edition, which is to recognize distinct entities on the basis of morphology, immunophenotype, genetic changes, and clinical features.
Convey better the clinical features of the entity. Lymphoma designation was changed either to “neoplasia” or “lymphoproliferative disorder” to denote either the low risk of progression to a full‐blown lymphoma in precursor lesions or to stress the indolent behaviour of the disease, respectively.
New provisional entities have been recognized.The various subtypes arise from the specific location from their origin with in the lymphoid tissue Fig-2. This lead to the differnet bevaiour clinical presentation , treatment and outcome in various subtypes of lymphoma.
The major contribution of molecular studies that has shed light onto the molecular pathways and chromosomal alterations of many disease entities has also been incorporated Fig-3.
Role of imaging
Most lymphomas presents as mass. Tissue diagnosis with histopathological examination with immunohistochemistry is mainstay for diagnosing and subclassifying the various lymphomas.
Imaging with PET CT plays an important role in localising,guiding biopsy staging, and response assesment.
Locational
CNS
Primary:
DLBCL, High grade Burkitt, Immune deficiency. Dural(malt),Intravascular
Secondary:
Parenchymal,leptomeningeal, Pituitary,Spinal, Neurolymphomatosis
Head and neck
Orbital,sinonasal,thyroid
Thoracic lymphoma
Pulmonary : Primary/Secondary, Balt, Aids
Pleural : Primary, Secondary
Mediastinal (Large B-cell), Breast, Cardiac.
GIT lymphoma
Bowel- Gastric, Small bowel , Large bowel
Visceral - Hepatobiliary lymphoma- Hepatic(Primary, Secondary),Splenic, Pancreatic
Genitourinary lymphoma
Renal , uterine, vaginal, cervical,testicular
Musculoskeletal lymphoma
Primary bone,secondarybone,muscle
Cutaneous lymphoma
Mycosis fungi ,Sezary
Multi-regional
Imaging is used for-
- Staging
- Response Assessment
International Conference of MalCML/Lugano Guideline for imaging.
CECT/CT
|
[18F] – FDG-PET/CT
|
• Marginal zone lymphoma (MZL) incl. MALT.•SLL/CLL.•Cutan, T-cell lymphoma.• Lymphoplasmacytic lymphoma (Waldenstrom) |
All other:
• DLBCL.• Follicular lymphoma.• Hodgkin lymphoma.• Mantle cell lymphoma (MCL) etc. |
Other radiopharmaceutical used in lymphoma imaging
Fluorothymidine F-18 (FLT)- has higher accuracy for grading however has a lower sensitivity.
Staging of lymphomas:
Modified Ann Arbor Staging System for Hodgkin's and Non-Hodgkin's Lymphoma is most commonly used system for stagging of lymphomas.
Fig-5 showing the modified Ann Arbor staging. Fig-6 depicting patients with various stages of Ann arbor stages.
Lugano classification is used for nodal stagiing of the lymphomas. Fig-7 showing the lugano classification.
Response Assessment :
PET CT is used for response assesment. Varous criteria are used for response assesment.
The timing of repeat PET CT is 6-8 weeks after chemotherapy and 2-3 months after radiotherapy.
Most commony used criteria for response assesment are
1.Deauville Criteria is a 5-point scoring system that utilizes five-point scoring system for the Fluorodeoxyglucose (FDG) avidity of a Hodgkin lymphoma or Non-Hodgkin lymphoma. Fig-7.
FDG uptake in the liver as main reference.
Mediastinal blood pool of less relevant.
2.RECIL criteria which is response categories based on assessment of target lesions , % Change in sum of diameters of target lesions from nadir. Fig-8.