The expression of myc and ras oncogene protein 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 lymphadenitides occurring in children 3-15 years old were examined by immunohistochemistry 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 this percentage was noted. In all cases of reactive lymphadenitides the number of cells where c-myc was expressed was less than 5%. The ras oncogene 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 between 2 and 10%, while in NHL and in reactive lymphadenitides there was no positivity. The above results indicate a frequent expression of c-myc protein in childhood lymphomas. This could reflect either an implication of c-myc oncogene in the pathogenesis of these tumor or an epiphenomenon of lymphomagenesis reflecting the proliferation rate of tumor cell population. Molecular biology studies are needed to clarify this issue.