A man was admitted for severe autoimmune hemolytic anemia with a mediastinal mass. He required corticosteroid treatment, which altered the first histological examination. Laparosplenectomy was performed and all histological sections were negative, but the hemolytic anemia was not improved. Finally, thoracotomy was performed when the mediastinal mass increased after reducing the corticosteroid treatment. Pathological examination revealed Hodgkin's disease associated with Castleman's disease. After chemotherapy and radiotherapy, the patient remains in complete remission.