Development of Acute Megakaryoblastic Leukemia with Isochromosome (12p) after a Primary Mediastinal Germ Cell Tumor in Korea

Department of Laboratory Medicine, Chung-Ang University College of Medicine, Seoul, Korea.
Journal of Korean medical science (Impact Factor: 1.27). 08/2011; 26(8):1099-102. DOI: 10.3346/jkms.2011.26.8.1099
Source: PubMed


The association of hematological malignancies with a mediastinal germ cell tumor (GCT) is very rare. We report one case of a young adult male with primary mediastinal GCT who subsequently developed acute megakaryoblastic leukemia involving isochromosome (12p). A 25-yr-old man had been diagnosed with a mediastinal GCT and underwent surgical resection and adjuvant chemotherapy. At 1 week after the last cycle of chemotherapy, his peripheral blood showed leukocytosis with blasts. A bone marrow study confirmed the acute megakaryoblastic leukemia. A cytogenetic study revealed a complex karyotype with i(12p). Although additional chemotherapy was administered, the patient could not attain remission and died of septic shock. This case was definitely distinct from therapy-related secondary leukemia in terms of clinical, morphologic, and cytogenetic features. To our knowledge, this is the first case report of a patient with mediastinal GCT subsequently developing acute megakaryoblastic leukemia involving i(12p) in Korea.

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    ABSTRACT: Germ cell tumor (GCT)-associated hematologic malignancies present a unique challenge to hematologists and hematopathologists. As most GCTs are of gonadal origin, only a small percentage occur at extragonadal sites in the midline. Extragonadal GCTs are believed to originate from the ectopic primordial germ cells that fail to migrate to the urogenital ridge during development. An overactive KIT pathway and overexpression of genes on chromosome 12p are strongly implicated in GCT development. Approximately 54% of extragonadal GCTs are located in the anterior mediastinum. This is disproportionally high among the midline structures, presumably due to a favorable microenvironment for GCT development in the developing thymus. The mediastinal nonseminomatous GCTs have two unique features. First, they are often refractory to current treatment modality with the worst prognosis among GCTs of all sites. Second, they have a tendency to give rise to secondary hematologic neoplasia. The outcome is grave for patients with GCT-associated hematologic malignancies. As standard chemotherapy used to treat their bone marrow-derived counterparts has been ineffective, the best treatment modality to achieve long-term survival is allogeneic hematopoietic stem cell or cord blood transplant for a very limited number of cases.
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