American Board of Internal Medicine (ABIM) Certification Practice Exam

When is rituximab added to the Hodgkin lymphoma treatment regimen?

1. In patients with B symptoms

2. In patients with CD20-positive disease

3. For all patients regardless of subtype

4. Only in patients with negative PET scans

The correct answer is: In patients with CD20-positive disease

Rituximab is added to the Hodgkin lymphoma treatment regimen specifically for patients with CD20-positive disease. This is because rituximab is a monoclonal antibody that targets the CD20 protein found on the surface of certain B cells. While Hodgkin lymphoma is primarily a B-cell malignancy, not all cases express CD20. Thus, testing for CD20 expression is crucial in determining whether rituximab can be effectively used as part of the treatment strategy. In scenarios where patients have B symptoms, which are indicative of a higher disease burden or systemic involvement, the addition of rituximab is not standard practice unless the disease is confirmed to be CD20-positive. Similarly, rituximab is not universally added for all patients regardless of subtype, as their specific pathology and molecular characteristics guide treatment decisions. The use of rituximab is not dependent on the results of PET scans; instead, it hinges on the expression of the CD20 antigen on the lymphoma cells. Therefore, the precise tailor-made approach to treatment is essential, emphasizing the significance of identifying CD20 expression before incorporating rituximab into the regimen.