Fig. 3.

a, b Session 2, case 11 represents an example of a composite lymphoma and illustrates distinct areas resembling classical Hodgkin lymphoma and primary mediastinal B cell lymphoma. The classical Hodgkin-like areas exhibit large atypical cells with Reed-Sternberg cell morphology (a), whereas the primary mediastinal B cell lymphoma-like areas show sheets of large atypical cells embedded in a fibrotic stroma (b). c–i Session 2, case 20 shows an example of classical Hodgkin lymphoma with aberrant T cell marker expression. The large Reed-Sternberg-like cells (c) express multiple T-lineage markers including CD3 (d), CD5 (e), and CD4 (f), in addition to weak expression of the B cell transcription factor PAX5 (g)