Analysis of PAX5 expression of Hodgkin’s and non-Hodgkin’s lymphomas: in comparison with routine panel

Aim of the study: To assess the expression of PAX5 in different types and stages of lymphomas and to study its utility in comparison with the classical pan B and T cell markers. Materials and Methods: Immunohistochemistry was done to detect the expression of PAX5, CD45, CD3, CD20, CD15 and CD30 in all cases of lymphoma reported for a period of two years. Results: 59 cases were reported as malignant lymphomas giving an overall incidence of 6.3% in our hospital. The age group ranged from 3 years to 75 years with a male preponderance. Nineteen cases were excluded owing to inadequate tissue samples. Of the 40 cases, 28 were nodal and 12 extra-nodal lymphomas. 33 cases were non-Hodgkin’s lymphoma and 7 were Hodgkin’s lymphoma. 23 out of the 40 cases were positive for PAX5 and out of 21 cases of B cell non-Hodgkin’s lymphoma, 18 were positive. Reed-Sternberg cells of Hodgkin’s lymphoma were positive in 5 cases. PAX5 was positive in most of the B cell non-Hodgkin’s lymphoma and Hodgkin’s lymphoma regardless of the stage, age, sex and site. PAX5 was negative in all T cell non-Hodgkin’s lymphoma and the cases of unclassified category. Conclusions: This study suggests that B cell neoplasms and Reed Stenberg cells strongly expressed PAX5 in comparison to classical lymphoma panel and hence can be a useful marker. However a larger prospective study on PAX 5 expression in Hodgkin’s Lymphoma is vital to look for an increased expression in subset of Indian population. Keywords: B-cell Lymphoma, Hodgkin’s lymphoma, Immunohistochemistry, PAX5, T-cell Lymphoma