Fig 3.

Sections show (HE 400×) (A) large, atypical lymphocytes with bi-lobation within a lymphohistiocytic background. There was extensive necrosis in the other parts (HE 400×). (B) Immunohistochemically, the atypical lymphocytes were positive for CD20 (>50%), CD30, CD79a, PAX5, MUM1, and BCL2, and negative for κ, lambda, CD3, CD10, CD15, CD68, BCL6, and c-MYC. ALK1 staining was negative. Atypical large lymphocytes were positive for EBER in situ hybridization. P53 staining was heterogeneously positive. PDL1 was also positive. ALK1, activin A receptor like type 1; BCL, B-cell lymphoma; CD, cluster of differentiate; c-MYC, cellular myelocytomatosis oncogene; EBER, Epstein-Barr encoding region; HE, hematoxylin and eosin; MUM, multiple myeloma oncogen; PAX5, paired box 5; PDL, programmed death-ligand.