RESUMEN
Objective To investigate the expression of PAX-5 in anaplastic large cell lymphoma, discuss the value and pitfalls of PAX-5 in the diagnosis and differential diagnosis of lymphomas. Methods A total of 269 T lymphomas were studied retrospectively.PAX-5 positive anaplastic large cell lymphoma was confirmed by immo-munohistochemistry and gene rearrangement analysis. Literature review was performed and the clinicopathological features were discussed.Results Two cases of anaplastic large cell lymphoma were found with aberrant expression of PAX-5. Conclusions As a relatively specific B cell marker, PAX-5 can also express in anaplastic large cell lymphoma. In the diagnosis of lymphomas, especially the differential diagnosis between classical Hodgkin lympho-ma and Anaplastic large-cell lymphoma, diagnosis errors should be avoided by interpreting PAX-5 immunohisto-chemistry in the context of clinical features, morphology, a panel of B- and T-lineage-associated antibodies, and gene rearrangement analysis.