Diagnostic Yield of PAX5 in Lymphoma

Background: Lymphoma is a heterogeneous group of neoplasm affecting any stage of lymphocyte development. Nowadays, WHO (2017) adapted their classification depending on their morphological, immunohistochemical appearance, and their clinical and molecular characteristics. Objective: To determine the expression of PAX5 in Hodgkin and Non Hodgkin lymphoma and their association with clinical parameters (age &site). Patients & Methods: During a period of 1 year starting from June 2019 to June 2020, 60 lymphoma patients" were included in this"prospective-retrospective"case series study from"medical records and histopathological results in governmental and private labs. Immunohistochemistry examination using PAX5 was performed, and data of the positive PAX5 expression were analyzed. Results: A total of 60 patients were recruited in this study with the majority (58%) were Non Hodgkin lymphoma, dominated by diffuse large B- cell lymphoma subtype (42.8%) and (42%) were Hodgkin lymphoma where nodular sclerosis subtype formed (52%) and mainly of the nodal site in both of them. The age range of Non Hodgkin lymphoma 7-76 years (median 50 years) and 5-67 years (median 21 years) for Hodgkin lymphoma and male predominance in both of them and there is no significant association between the site and lymphoma (p value=0.0647) while a significant association with age (p value =0.037). Moreover, the immunohistochemical examination demonstrates that positive PAX5 was expressed in 77% of Non Hodgkin lymphoma and 100% of Hodgkin lymphoma. The P-value between them was 0.016, which was statistically significant ,no matter of using PAX5 or CD30 in"the diagnosis of Hodgkin lymphoma,in other hand"there is a significant difference between PAX5 and CD3 expression (P value=0.004), while it is not statistically significant when comparing PAX5 and CD20 (P-value =0.317) in the diagnosis of Non Hodgkin lymphoma . Conclusion: This study demonstrates that PAX5 is one of the most sensitive and reliable immunohistochemical marker in diagnosing Hodgkin lymphoma and B-cell Non Hodgkin lymphoma.