Platelet-derived growth factor receptor-alpha (PDGFR-alpha) expression in the Hodgkin/Reed-Sternberg cells of nodular sclerosing Hodgkin's disease has been demonstrated in 2 studies. Additional receptor tyrosine kinases have also now been documented. This communication reports the correlative expression in nodular sclerosing Hodgkin's disease of activated (phosphorylated) p70S6K, one of the putative downstream effectors common to receptor tyrosine kinase signaling.