Fig. 4

Case 4: a and b illustrate low-magnification and high-magnification appearance of respectively(H&E stain), showing effacement of the lymph node architecture, replaced by varying sized nodules with the presence of three distinct layers of cells in the nodules comprising inner most layer of dark-staining neoplastic centrocytes surrounded by a layer of pale-staining neoplastic centroblasts followed by the outskirt of a thin layer of small lymphocytes assembled outside the FDC meshwork, confirmed by IHC staining for CD21, CD20, CD10 and BCL2 (c,d,e and g). CD3 stain reveals T cells in the outmost layer (f). FISH demonstrates rearranged BCL2 gene (h), the neoplastic cells show 1- fused, single red, and single green signals (the red arrow) whereas the normal cells show two fused signals (the white arrow)