OX40/CD134 expression in classical Hodgkin’s disease. (A) OX40/CD134 immunostain of nodular sclerosis Hodgkin’s disease shows numerous positive cells within neoplastic nodules. Adjacent uninvolved nodal tissue shows only rare OX40/CD134⁺cells. (B) OX40/CD134⁺ benign T cells cluster around RS cells (arrows) with one RS cell showing possible OX40/CD134 membrane staining (lower arrow).