In this post, we shall explain Lymphoma Staging PET-CT. Many lymphoma staging systems have been developed for both Hodgkin’s lymphoma and non-Hodgkin’s lymphoma. Currently the most widely used is the classification of Legnano staging, which also specifically defines the criteria for the response to treatment treated by PET-CT or CT-only. Patients undergoing immunomodulatory therapy can also be assessed by modifying the Lugano standard called LYRIC, which introduces a new category of “irrational reactions”.
Clinical and radiation oncology specialists.
Positron emission tomography-computed tomography (PET-CT) imaging is considered standard for fluorodeoxyglucose (18F)-avid lymphomas like Hodgkin’s lymphoma (HL), diffuse large B-cell lymphoma (DLBCL) (Fig. 5.2), follicular lymphoma (FL), mantle cell lymphoma (MCL), and Burkitt lymphoma (BL).
For staging purposes, a modified Ann Arbor staging system is recommended Stages I and II are considered limited diseases whereas III and IV are advanced ones leading to different treatment options.
Tonsils, Waldeyer’s ring, and spleen are considered nodal tissue; (S) stands for spleen involvement, (E) for extranodal disease.
Lesions should be measured in two dimensions: LDi (long-axis diameter) and SDi (short-axis diameter). They should represent the overall disease burden.
Nodal site is measurable if LDi > 1.5 cm, extranodal—if LDi > 1.0 cm.
Splenomegaly is defined as spleen craniocaudal size > 13 cm.
Bulky disease in HL has been defined as a nodal mass of 10 cm or greater than one-third of the thoracic diameter at any level of thoracic vertebrae.
For FL, the cut-off value of 6 cm has been suggested, and for DLBCL 6 to 10 cm. It is recommended to record the longest measurement by CT scan making the term (X) redundant.
whereas CT is indicated for nonavid ones like mucosa-associated lymphoid tissue (MALT) or chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL).3
If PET-CT is performed in HL, bone marrow biopsy is no longer indicated.3 It is only needed in DLBCL cases where PET-CT is negative and discordant histology would directly impact patient management.
In a clinical trial setting, it is recommended to report up to 6 index lesions (measurable nodal and extranodal) and up to 10 nonindex lesions representing the rest of the disease. Some indolent lymphomas, e.g., FL, can transform into aggressive ones like DLBCL characterized by a markedly higher FDG uptake, (▶ Fig. 5.2) directly affecting patient management.
False-positive results may be caused by physiological uptake in Waldeyer’s ring, thymus, intestine, adnexa, or due to brown adipose tissue activation. Misdiagnosis may also occur due to high intestine activity (antidiabetic drugs), bone marrow activation (chemotherapy/granulocyte- colony-stimulating factor [GCSF]), or lower uptake within the lesions (corticosteroid therapy). PET-CT quantitative methods (e.g., metabolic tumor volume [MTV] and total lesion glycolysis [TLG]) may improve visual assessment. They should be explored as prognostic factors and validated in further clinical trials.
Staging of lymphoma
Staging is the process of determining which parts of your body are affected by lymphoma (how ‘advanced’ your lymphoma is). Your tests and scans help doctors work on the stage of your lymphoma when you are diagnosed.
It is important to have lymphoma because it helps your medical team plan the most appropriate treatment for you. Different types and stages of lymphoma respond to a combination of different types and treatments.
The same staging system is used for Hodgkin and non-Hodgkin lymphomas, with a few exceptions:
Having Hodgkin’s lymphoma in children is slightly different from staging in adults.
Staging for chronic lymphocytic leukemia (CLL), often considered a form of non-Hodgkin’s lymphoma, uses a different system. This is described on our web page about CLL. Small lymphocytic lymphoma (SLL), a form of CLL affecting lymph nodes, is staged like other non-Hodgkin’s lymphomas.
Cutaneous (skin) lymphomas (lymphomas beginning in the skin) behave differently from other lymphomas and have different locations. The orbit of skin lymphomas depends on whether they are cell lymphomas or T-cell skin lymphomas.
Waldenstrom’s macroglobulinemia, a rare type of non-Hodgkin’s lymphoma that often does not affect the lymph nodes, does not have a standard staging system.