ALK and lymphoma: HRS cells express the tumour necrosis factor receptor family member, CD30 (TNFRSF8), which is common to cHL and other CD30–positive lymphomas such as anaplastic lymphoma kinase-positive, anaplastic large cell lymphoma (ALK+ ALCL), anaplastic lymphoma kinase-negative, anaplastic large cell lymphoma (ALK− ALCL), cutaneous ALCL, and CD30–positive diffuse large B cell lymphoma3,4.