Lymphoma for Radiology Board Review Part 3
Questions and answers on lymphoma for radiology board review, part 3. Prepare to succeed!
Show Notes/Study Guide:
What is the most common subtype of non-Hodgkin lymphoma?
Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of NHL. Less aggressive NHL subtypes such as follicular lymphoma can transform into the more aggressive DLBCL over time. If you see images of an indolent lymphoma that rapidly progresses on imaging, DLBCL is in the differential.
True or false? Most cases of post-transplant lymphoproliferative disease occur greater than 1 year after organ transplantation.
False. Most cases of PTLD occur within 1 year of transplant.
Common treatment of PTLD includes what?
First, reduction of immunosuppression. Therefore, you must strike a balance between risk of PTLD and risk of transplant allograft rejection. Other treatment options include surgery, radiation, and chemotherapy.
What is the hallmark genetic translocation in cases of follicular lymphoma?
A t(14:18) translocation is classic for follicular lymphoma.
What are some classic cytogenetic features of diffuse large b cell lymphoma?
c-MYC, BCL2 and/or BCL6 rearrangements.
What is the Deauville score?
The Deauville score is a 5-point score for use of staging lymphoma based on degree of uptake on FDG PET/CT. Key is to remember that a score of 4 or 5 shows uptake above that of liver and denotes active/progressive disease (if new disease this is a score of 5). A score of 1-3 denotes absent uptake (score of 1) or uptake below (2) or equal (3) to that of liver (score of 2 has uptake below liver and below or equal to mediastinal blood pool, score of 3 has uptake above mediastinal blood pool but below or equal to liver).
Which Deauville scores can denote a complete response to therapy?
Deauville scores of 1, 2, or 3 can denote a complete metabolic response to therapy. On the other hand, Deauville scores of 4 or 5 can denote stable disease, progressive disease, or partial response depending on whether uptake is the same, better, or worse compared to prior and whether there is new disease (if new disease it is a Deauville score of 5).
Bonus tip: It is possible to be considered a CR when using Deauville score even if there is a large residual mass, if uptake is absent or very low.
Diffuse bone marrow uptake can be a sign of lymphoma bone marrow involvement but can also be seen in what other settings?
Diffuse bone marrow uptake can be seen with lymphoma but can also be seen other settings such as bone marrow stimulation from filgrastim or other colony stimulating factor agents, bone marrow rebound post-chemotherapy, or bone marrow rebound from anemia of other causes.
How can bone marrow involvement of lymphoma be confirmed?
Bone marrow biopsy is frequently performed as part of lymphoma evaluation and staging, most commonly in the iliac bone. On imaging, look for linear subcutaneous fat stranding in a linear manner in the posterior iliac subcutaneous tissues along with FDG uptake in the subcutaneous tissues and iliac bone as imaging manifestations of recent bone marrow biopsy.
How can you differentiate between brown fat uptake and lymph node uptake on FDG PET/CT?
Uptake of brown fat / brown adipose tissue can look very similar to hypermetabolic lymphadenopathy on FDG PET only images. However, when you evaluate the associated CT images there will be no associated lymph nodes in the region(s) of uptake on PET imaging, but only normal fat will be seen in the areas of uptake. The most common locations for brown fat uptake are the mediastinum, neck and supraclavicular regions, paravertebral regions, and upper para-aortic regions. You must scrutinize areas of brown fat uptake to see if there are co-existent lymph nodes as you can have mixed lymphadenopathy and brown fat, with both showing uptake. If areas of uptake correspond with lymph nodes this is potentially pathologic, if areas of uptake show only fat on CT, and the pattern is analogous with brown fat, then brown fat uptake is confirmed. Note that brown fat uptake is a potential cause of diagnostic error for lymphoma staging so it is important to be aware of this entity. Brown fat uptake is also something that is easily testable on radiology and nuclear medicine board examinations.
What can be done to minimize brown adipose FDG uptake?
Various strategies exist including warming the PET uptake rooms where the patient waits prior to PET imaging, administering benzodiazepines or beta blockers in patients who have had prior brown fat uptake, and encouraging patients to stay warm prior to arriving at the imaging suite for FDG PET imaging.
