Adult and Pediatric Hodgkin: Immunophenotype, EBER Expression, and B-Cell Differentiation
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Background: Hodgkin's Lymphoma (HL) differs from non-Hodgkin's lymphoma (NHL) in its bimodal presentation. Whether adult differs from pediatric Hodgkin in its histological types, immunophenotype, presence or absence of EBV infection, is still a subject of debate. Design: To further elucidate this problem, we studied 62 cases of classical Hodgkin's lymphoma (CHL): 28 children (<15 years) and 34 adolescents ( 15 years) for the immunohistochemical expression of CD15, CD30, CD45, CD20, the BSAP (Pax-5) and CD138 (Syndecan-1) using both the standard peroxidase and APAAP techniques. Moreover, the Epstein-Barr Virus encoded RNA (EBER) expression was studied using the insitu hybridization technique. All studies were done on formalin-fixed paraffm-embedded material. Results: In the pediatric group, the positive expression of CD15, CD30, CD45, CD20 & CD138 was 60.7%, 100%, 7.1%, 28.6%, 64.3%, respectively. In the adult group, the expression was 50%, 94.1%, 17.6%, 17.6% and 29.4% respectively. Pax-5 (BSAP) was 100% positive in both groups. EBER expression was found in 50% of pediatric and 20.6% of adult cases. In the adult group, CD15 expression positively correlated with both Syndecan-1 and EBER expression. (p=0.019 and p=0.009 respectively). In the pediatric group, EBER expression was more in younger age (p=0.007) and in mixed cellularity subtype (p=0.013) Conclusion: pathogenesis of pediatric Hodgkin seems to be different from adult, the Epstein Barr Virus possibly being the initiating event. The expression of Syndecan and its positive correlation with CD15 (a previously reported good prognostic factor) could define a subset of CHD with a switch into the immunoglobulin secreting phenotype with a better prognostic potential.