Hodgkin vs. non-Hodgkin lymphoma
Also known as: hodgkin lymphoma vs non-hodgkin lymphoma
Both are cancers of lymphocytes, but Hodgkin lymphoma is defined by the presence of Reed-Sternberg cells and spreads in an orderly, contiguous fashion between adjacent lymph node groups. Non-Hodgkin lymphoma lacks Reed-Sternberg cells and spreads unpredictably, often involving extranodal sites.
The dividing line is histologic. Hodgkin lymphoma is diagnosed by finding Reed-Sternberg cells — large binucleate or multilobed cells with prominent nucleoli, often described as having an owl-eye appearance — on lymph node biopsy. These malignant cells are actually a minority of the tumor mass; most of the node is filled with a reactive infiltrate of lymphocytes, eosinophils, and plasma cells drawn in by cytokines the Reed-Sternberg cells release. Non-Hodgkin lymphoma comprises every other lymphoid malignancy, a heterogeneous group dominated by B-cell neoplasms such as follicular lymphoma, diffuse large B-cell lymphoma, and Burkitt lymphoma.
Clinical behavior differs in ways that are directly testable. Hodgkin lymphoma usually presents with painless enlargement of a single group of nodes, most often cervical or mediastinal, and spreads contiguously to the next adjacent group — which is why it is more often localized at diagnosis and more amenable to staged, targeted therapy. Non-Hodgkin lymphoma is more likely to present with multiple noncontiguous nodal groups involved, frequent extranodal disease, and a higher likelihood of being widespread at the time of diagnosis.
Epidemiology and associations also separate them. Hodgkin lymphoma shows a bimodal age distribution, with peaks in young adults and again after age 55, and is associated with Epstein-Barr virus. Constitutional B symptoms — fever, drenching night sweats, and unexplained weight loss — are more characteristic of Hodgkin lymphoma and carry staging significance. Non-Hodgkin lymphoma incidence rises with age and is associated with immunosuppression, including HIV infection and post-transplant states, as well as with autoimmune disease and certain chronic infections such as Helicobacter pylori in gastric MALT lymphoma.
USMLE Step 1 tests this comparison in the hematology and oncology pathology material. High-yield points include recognizing Reed-Sternberg morphology, knowing that Hodgkin disease spreads contiguously while non-Hodgkin does not, and matching specific non-Hodgkin subtypes to their characteristic translocations and patient populations.
Key takeaways
- Reed-Sternberg cells define Hodgkin lymphoma and are absent in non-Hodgkin lymphoma.
- Hodgkin lymphoma spreads contiguously between adjacent nodal groups; non-Hodgkin lymphoma spreads noncontiguously and often extranodally.
- Hodgkin lymphoma has a bimodal age distribution and is associated with Epstein-Barr virus.
- Non-Hodgkin lymphoma incidence increases with age and is associated with immunosuppression and HIV.
- B symptoms — fever, night sweats, and weight loss — are more typical of Hodgkin lymphoma and affect staging.