Differentiating Hodgkin vs Non-Hodgkin Lymphoma
The fundamental distinction between Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) is pathologic: HL is defined by the presence of Reed-Sternberg cells (in classical HL) or lymphocyte-predominant "popcorn" cells (in nodular lymphocyte-predominant HL), while NHL lacks these characteristic cells and consists of various other malignant lymphoid cell types. 1
Pathologic and Immunophenotypic Differences
The diagnosis hinges on identifying specific malignant cells through excisional lymph node biopsy—fine-needle aspiration is insufficient for either diagnosis 2, 1:
Classical Hodgkin lymphoma (95% of HL cases): Reed-Sternberg cells are embedded in an inflammatory background where malignant cells represent only a small fraction of total cells 1. These cells stain CD30+ and CD15+, occasionally CD20+, but are CD45- 3
Nodular lymphocyte-predominant HL (5% of HL cases): Contains "popcorn cells" (LP cells) constituting only 0.1-1% of nodal cells 1. These cells are CD20+ and CD45+ but CD15- and CD30- 3
Non-Hodgkin lymphoma: Lacks Reed-Sternberg or popcorn cells entirely; consists of various malignant lymphoid populations depending on subtype 1. Immunophenotyping patterns vary widely by NHL subtype 4
Critical pitfall: Rare NHL cases can contain Reed-Sternberg-like cells, making immunohistochemistry essential rather than optional 1.
Epidemiologic and Clinical Distinctions
Age Distribution
HL: Characteristic bimodal distribution with peaks at ages 15-30 years and after age 55 1, 5. Young adults (20-40 years) are most commonly affected 3, 6
NHL: Median age >60 years, with incidence increasing with age 7. No bimodal pattern 4
Incidence
HL: 2.3 cases per 100,000/year in the European Union, representing approximately 5% of all lymphomas 3, 6, 1
NHL: Approximately 30-40% of adult lymphomas are diffuse large B-cell lymphoma alone, with NHL representing the vast majority of lymphoid malignancies 6, 4
Presentation Pattern
HL: Spreads in a contiguous, predictable pattern from one lymph node group to adjacent groups 5. Over 60% present with cervical lymphadenopathy 5. Mediastinal involvement is common, particularly in nodular sclerosis subtype 5. Isolated inguinal involvement is atypical 5
NHL: Random, non-contiguous distribution is typical 4. Extranodal involvement is more common than in HL 4
Diagnostic Work-Up Requirements
Both require excisional lymph node biopsy, but staging differs slightly 2, 1:
Mandatory for Both
- PET-CT for staging (FDG-avid histologies) 2
- Contrast-enhanced CT of neck, chest, abdomen 3
- Full blood count, ESR, LDH, liver enzymes, albumin 3
- HBV, HCV, HIV screening 3
Key Staging Difference
- Bone marrow biopsy is no longer indicated for HL when PET-CT is performed due to high sensitivity 3, 2, 6
- Bone marrow biopsy may still be needed for certain NHL subtypes depending on histology 2
Symptom Documentation
- B symptoms (fever >38.3°C, night sweats, >10% weight loss over 6 months) are formally recorded and affect staging designation in HL only 2
- Additional HL-specific symptoms include pruritus and alcohol-induced pain 3
Treatment Approach Differences
Hodgkin Lymphoma
- Standard regimen: ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine) with or without radiotherapy 4
- Alternative regimens: Stanford V or BEACOPP 4
- Cure rate: ≥80% with modern treatment 1
- Treatment focus is on minimizing long-term toxicity rather than improving cure rates 1
Non-Hodgkin Lymphoma
- Standard regimen for aggressive NHL: R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) 8, 4
- Indolent NHL: Bendamustine, rituximab, or lenalidomide 9, 4
- Treatment varies significantly by NHL subtype 4
Critical distinction: Rituximab (anti-CD20 antibody) is standard for most B-cell NHL but not used in classical HL (where Reed-Sternberg cells are typically CD20-negative) 8. It may be considered in nodular lymphocyte-predominant HL where LP cells are CD20+ 3.
Prognosis
HL: Highly curable (≥80%) with decades of potential survival, making late toxicity (secondary cancers, cardiovascular disease) a major concern 1, 5
NHL: Prognosis varies dramatically by subtype, stage, and age, with aggressive subtypes requiring immediate treatment and indolent subtypes sometimes managed with observation 4
Important caveat: When both diagnoses occur in the same patient over time, molecular studies demonstrate they typically represent separate clonal origins rather than transformation from one to the other 10.