EBV RNA in both CD20⁺ and CD20⁻ B cells in a lymph node from patient 16. (A) Lymph node biopsy shows polymorphic B-cell lymphoma. (B) In situ hybridization shows that the tumor cells are positive for EBER. Few cells express the CD20 B-cell marker (C), whereas many cells express the CD3 T-cell (D), CD79 B-cell (E), and Pax-5 B-cell (F) markers.