Fig. 5.

a–d Session 3, case 10: THRLBCL of the spleen with micronodular involvement. Micronodular involvement of the white pulp of the spleen characterized by scattered large neoplastic B cells in a background of reactive T cells (a). CD20 expression highlights the abnormal infiltrating nodules compared to the normal white pulp (b). PD1-positive T cells are scattered and T cell rosettes around the large neoplastic B cells are absent (c). THRLBCL shows areas of progression to DLBCL (d). e–j Session 3, case 17: B cell lymphoma unclassifiable with features intermediate between DLBCL and CHL. Lymph node with a diffuse infiltration (e) and numerous large cells with typical RS cell morphology (f). The RS-like cells are negative for CD15 (f, insert), strongly and uniformly positive for CD20 (g), CD79a (h), Oct 2 (i), and EBER ISH (j). k–n Session 3, case 20: B cell lymphoma unclassifiable with features intermediate between DLBCL and CHL. Lymph node with vaguely nodular infiltration reminiscent of NLPHL but with numerous large cells with typical RS cell morphology (k). The RS cells are strongly and uniformly positive for CD20 (l), Oct 2 (m), and EBER ISH (n), in addition to CD15 and CD30 positivity