Mediastinal mature teratoma with coexistence of angiosarcoma, granulocytic sarcoma and a hematopoietic region in the tumor: A rare case of association between hematological malignancy and mediastinal germ cell tumor

An association between mediastinal germ cell tumors (MGCT) and hematological malignancies (e.g. acute leukemia, malignant histlocytosis) has been recognized since 1984. A rare case of mediastinal mature teratoma with angiosarcoma, a hematopoietic region and granulocytic sarcoma is reported in a 29-year-old male. The resected tumor was 9.0 × 6.5 cm, weighed 65 g and showed extensive necrosis, forming a cyst. The hlstological features of the tumor showed a mature teratoma, which contained a large gland lined by ciliated epithelium, hyalinous cartilage, a paraganglion-like structure, well-diierentiated angiosarcoma with atypical hematopoiesis composed of CD34-positive cells, and mallgnant round cells. The malignant round cells did not stain for CD34 but were positive for leukocyte common antigen (LCA) and c-kit product. From these findings, the round cells were dlagnosed as granulocytic sarcoma. The patient died of metastasis of the granulocytic sarcoma in the tonsils and cervical lymph nodes 8 months after surgery. A leukemic condition was not present throughout the clinical course. The association between MGCT and hematological malignancy is a distinctive syndrome. However, its pathogenesis is still obscure and the origin of the hematopoietic malignancy has not been fully elucidated. In this particular case, it Is suggested that the granulocytic sarcoma might have arisen from the abnormal hematopoietlc area in the mediastlnal teratoma.