THE EXPRESSION OF MYC AND RAS ONCOGENE PROTEINS IN CHILDHOOD LYMPHOMAS

Paraffin sections from 21 cases of Hodgkin's disease (HD), 18 cases of non-Hodgkin's lymphomas (NHL) and 15 cases of reactive lymphadenitide s occurring in children 3-15 years old were examined by immunohistoche mistry for the presence of c-myc and pan-ras oncogene products. In all cases of childhood lymphomas studied c-myc protein was expressed. The highest percentage was in HD where in 29% of cases the percentage of positive cells was greater than 20%, while in only 6% of NHL cases thi s percentage was noted. In all cases of reactive lymphadenitides the n umber of cells where c-myc was expressed was less than 5%. The ras onc ogene was also found in HD but with a lesser degree of positivity than c-myc. In 48% of these cases the number of positive cells ranged betw een 2 and 10%, while in NHL and in reactive lymphadenitides there was no positivity. The above results indicate a frequent expression of c-m yc protein in childhood lymphomas. This could reflect either an implic ation of c-myc oncogene in the pathogenesis of these tumors or an epip henomenon of lymphomagensis reflecting the proliferation rate of tumor cell population. Molecular biology studies are needed to clarify this issue.