Flowcytometric immunophenotyping in the diagnosis of pediatric lymphoma: how reliable is it and how can we optimize its use?

We aimed to evaluate the role of flowcytometric immunophenotyping (FCI) as an adjunct to histologic examination in pediatric lymphoma. We conducted a retrospective review of 39 fresh tissue samples and 2 pleural fluids submitted to the histopathology department with a clinical suspicion of lymphoma during a 4-year period, where FCI was performed. The FCI results were correlated with the final histologic diagnosis. The study comprised 38 lymphoid lesions and 3 nonlymphoid tumors. The concordance of FCI for all lesions was 71% and that for non-Hodgkin lymphoma was 75%. When Hodgkin lymphoma was excluded, the correlation was 93.1%. In 3 cases of nonhematologic tumors, FCI was useful in excluding a lymphoma. In one of them, FCI supported the diagnosis of neuroblastoma when CD81, CD9, GD2, and CD56 were added to the FCI panel. FCI produced rapid same-day results with a high sensitivity for benign lymphoid lesions and non-Hodgkin lymphoma. It was not helpful for Hodgkin lymphoma. Although the main application of FCI was to assess lymphoid lesions, it was also useful in the identification of nonlymphoid tumors, especially neuroblastoma. As the prevalence of lymphomas in children differ from that in adults, we believe that the algorithm proposed by us to triage specimens using imprint cytology can optimize the use of FCI in routine pediatric pathology practice.