## Distinguishing cHL from NLPHL ### Key Histological Differences **Key Point:** CD20 expression is the most reliable immunophenotypic discriminator between cHL and NLPHL. Classical Hodgkin lymphoma cells are CD20-negative, whereas NLPHL cells (LP cells) are CD20-positive. ### Immunophenotypic Profile Comparison | Feature | Classical HL | NLPHL | |---------|-------------|-------| | **CD20** | Negative | **Positive** | | **CD45** | Negative | Negative | | **CD30** | Positive | Negative/weak | | **CD15** | Positive | Negative | | **EBV** | Often positive | Negative | | **CD4+ T-cell background** | Abundant | Sparse | ### Morphological Context **High-Yield:** Both cHL and NLPHL contain abnormal cells (Hodgkin cells and Reed-Sternberg cells in cHL; LP cells in NLPHL) surrounded by reactive lymphocytes, eosinophils, and plasma cells. However, the immunophenotype is the gold standard for distinction. ### Why CD20 Matters **Clinical Pearl:** CD20 positivity in NLPHL cells makes them B-cell derived and explains why NLPHL: - Has a better prognosis than cHL - May respond to rituximab (anti-CD20 monoclonal antibody) - Shows a different clinical behavior (lower stage at presentation, better survival) ### Mediastinal Involvement Pattern **Tip:** While mediastinal involvement is common in cHL (especially nodular sclerosis subtype), it is rare in NLPHL. However, this is an epidemiological feature, not a definitive histological discriminator. The immunophenotype remains the gold standard. [cite:Robbins 10e Ch 13]
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