Reactive Bcl2-positive germinal centres in paediatric tonsils: expanding the spectrum of lymphoma mimickers in children and adolescents

Aims: Bcl2-positive germinal centres (GCs) have never been documented in reactive lymphoid hyperplasia (RLH). Here we describe such phenomenon in paediatric chronic tonsillitis (PCT), addressing the differential diagnosis with paediatric lymphomas. Methods and Results: Six PCT cases with Bcl2-positive GCs were retrieved from a retrospective series of 166 tonsillectomies from children and adolescents. Clinical-pathological data were collected, also considering the status of IG rearrangements and BCL2 translocations. PCT with Bcl2-positive GCs mostly occurred in males (5/6 cases; median age: 5 years). Histologically, tonsil architecture was preserved and Bcl2 positivity was documented in a minority of GCs. Bcl2-positive GCs expressed CD10 and Bcl6 and had a high proliferation index. All cases had polyclonal IG rearrangements without evidence of monotypic kappa and lambda chains by RNAscope. BCL2 translocations were lacking in all the cases. Conclusion: Bcl2-positive GCs in PCT are a rare and benign phenomenon, expanding the spectrum of lymphoma-mimicking paediatric RLH.