This study is a survey in Japan of Brentuximab Vedotin used to treat children or teenagers with Hodgkin lymphoma (HL). The study sponsor will not be involved in how the participants are treated but will provide instructions on how the clinics will record what happens during the study. The main aim of the study is to check for side effects related from Brentuximab Vedotin especially myelosupression, peripheral neuropathy, and lung disorder. During the study, pediatric participants with HL will take Brentuximab Vedotin injection and AVD treatment (doxorubicin hydrochloride, vinblastine sulfate, and dacarbazine) according to their clinic's standard practice. The study doctors will check for side effects from Brentuximab Vedotin for 26 weeks.