Diagnostic Utility of PAX5 in Hodgkin and Non-Hodgkin Lymphoma: A Study from Northern India

Abstract

Introduction: PAX5 is an immunomarker of B-cell origin and useful in the diagnosis of lymphoma. There is hardly any study on PAX5 expression in Indian patients with lymphoma.

Aim: To evaluate the diagnostic utility of PAX5 as an adjunct immunohistochemical marker in the diagnosis of Hodgkin Lymphoma (HL) and Non-Hodgkin Lymphoma (NHL).

Materials and methods: Immunohistochemistry was performed against CD20, CD3, CD15, CD30, and PAX5 on formalin fixed paraffin embedded tissue of 71 cases of lymphoma and CD20, CD3 and PAX5 in control samples of reactive lymph nodes. Frequency, mean values, and percentage were calculated. Fisher's-exact test and test for analysis of variance were applied.

Result: For 24 cases of HL and 47 cases of NHL, the mean age of patients was 17.6±14.8 years and 44.1±21.6 years, respectively. The male: female ratio for both HL and NHL were 1.7:1. Among NHL cases, the numbers of B-cell and T-cell types were 39/47 (83%) and 8/47 (17%), respectively. In comparison to control samples, PAX5+ expression was seen in 23/24 (95.8%) cases of HL (p=1.000) and 32/39 (82%) cases of B-NHL (p=0.0834). All the cases of T-NHL showed negative expression of PAX5 (p<0.0001). Analysis of variance between NHL, HL and control samples was statistically significant (p<0.0001).

Conclusion: PAX5 staining between control samples and cases of classical HL and B-NHL was statistically not significant, whereas, statistically significant difference was observed with T-NHL. Thus, PAX5 may be used as an adjunct marker in the diagnosis of classical HL and B-NHL.

Keywords: B-cell specific activator protein; Hodgkin/Reed-Sternberg cell; Immunohistochemistry; Lymphoproliferative disorder.

[Table/Fig-2]:

(a) Reed-Sternberg cell (arrow) of HL (Haematoxylin and eosin stain, 1000×); (b) CD15+ expression in Hodgkin cells (arrows) of HL (Diaminobenzidine, 1000×); (c) Weakly positive nuclear expression of PAX5 in Hodgkin cells (arrows) (Diaminobenzidine, 400×); (d) Sheets of large atypical lymphoid cells in a case of NHL (Haematoxylin and eosin stain, 400×); (e) Strong membranous positivity of CD20 in NHL (Diaminobenzidine, 400×); (f) Strongly positive nuclear expression of PAX5 in neoplastic cells of B-cell NHL (Diaminobenzidine, 400×); (g) Sheets of monomorphic atypical lymphoid cells in NHL (Haematoxylin and eosin stain, 400×); (h) Strongly and diffusely positive membranous expression of CD3 in NHL (Diaminobenzidine, 400×); (i) Negative PAX5 expression in T-cell NHL. Note scattered strong PAX5 positive B lymphocytes in the background (Diaminobenzidine, 400×).