a FL (left) can display a polymorphous and heterogeneous morphology simulating a reactive pattern (right). H&E. ×400. b Immunophenotyping. FL abnormal B-cell population (light blue): CD10+^B, CD38+ heterogeneous, with light chain κ restriction. Color refers to the online version only. c Reactive B-cell polyclonal population (light blue) expressing light chain κ (orange) and light chain λ (green) restriction, T cells (yellow), NK cells (red), and plasma cells (pink). Colors refer to the online version only.