縦隔混合性悪性胚細胞腫瘍切除後に発症した急性巨核芽球性白血病

Acute Megakaryoblastic Leukemia Developed after the Surgical Treatment of Mediastinal Malignant Germ Cell Tumor

縦隔などの性腺外に発生する胚細胞腫瘍は全胚細胞腫瘍の2～5％と比較的まれであるが，時に若年例において血液悪性腫瘍を合併することがある．われわれは縦隔原発混合性胚細胞腫瘍摘出後の経過観察中に急性巨核芽球性白血病を発症した症例を経験したので報告する．

A 26-year-old man was admitted to our hospital for an examination of a mediastinal tumor. Chest computed tomography （CT） showed a giant anterior mediastinal tumor narrowing the trachea and right main bronchus. Although needle biopsy could not be done because of patient respiratory condition, non-seminomatous mediastinal germ cell malignant tumor was strongly suspected by high level of serum AFP without no abnormal finding in his testis. After 1 cycle of chemotherapy by cisplatin, etoposide and bleomycin, the mediastinal tumor decreased in size. Percutaneous biopsy was challenged, however, definite diagnosis could not be established and the surgical resection was performed. The tumor was pathologically diagnosed as mature teratoma with elements of a yolk-sac tumor and some sort of sarcoma. Sudden onset of back pain and thrombocytopenia were encountered 5 months after the operation. Hematologic examination confirmed acute megakaryoblastic leukemia, and remission-induction therapy and allogeneic hematopoietic stem cell transplantation were performed. Twelve months after the operation, the patient is well without recurrence of either disease.