Immunohistochemical expression of p53, bcl-2, and p21waf1 in 48 Argentinean children with non-Hodgkin lymphoma

Background: Lymphoma accounts for 10% of all childhood cancers in developed countries. In Argentina, the incidence is 13.6%; of these, 53% are non-Hodgkin lymphomas (NHL) and 47% are Hodgkin lymphomas. Overexpression of p53, p21(waf1), and bcl-2 has been studied mainly in adults with NHL and correlated with clinical features and survival. The authors' aim was to analyze overexpression of these cellular oncogenes in children with NHL. Methods: Formalin-fixed paraffin-embedded lymph node biopsies from 48 children with NHL were studied by immuno-histochemistry with monoclonal antibodies for p53, bcl-2, and p21(waf-1). Results: Overexpression of p53 was detected in 81% of cases; bcl-2 positivity was 46% and p21(waf1) positivity was 42%. The p53/p21(waf1) expression patterns (types IV and V patterns), which correspond to the overexpression of nonfunctional p53, accounted for 46% of NHL. None of the studied oncogene patterns correlated with poor clinical patient outcome or histologic subtype. Conclusions: Of 81% of cases with p53 overexpression, 46% exhibited a nonfunctional p53 pattern, and this may contribute to dysregulation of proliferation, bcl-2 expression in up to 46% of cases may reflect a failure of bcl-2 downregulation in pre-B and immature B cells.