A 35-year-old woman has enlarged cervical lymph nodes. Biopsy shows nodular sclerosis with lacunar cells, eosinophils, plasma cells, and lymphocytes. Tumor cells are CD15+, CD30+, CD45−. Which additional marker confirms the B-cell lineage of the Reed-Sternberg cell?
- A CD3
- B PAX5 (weak/dim nuclear expression) ✓
- C TdT
- D MPO
Correct answer: B. PAX5 (weak/dim nuclear expression)
Explanation
Classical Reed-Sternberg cells retain dim/weak PAX5 (B-cell transcription factor) expression despite losing most other B-cell markers (CD20, CD79a are usually negative). PAX5 positivity alongside CD15+ and CD30+ is diagnostically helpful in confirming the B-cell origin of classical Hodgkin lymphoma. CD3 is a T-cell marker; TdT marks precursor lymphoblasts; MPO marks myeloid cells.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.