A Case of CD7+, CD56+ Myeloid/Natural Killer Cell Precursor Acute Leukemia with Mediastinal Mass

Twenty seven years old female complained of pleural fluid, neck lymph node swelling and mediastinal mass. The cytologic examination of pleural fluid and neck lymph nodse biopsy revealed malignant lymphoma. However immature blasts, which were peroxidase and PAS negative and morphologically diagnosed as M0 by FAB classification, and were CD7, CD19, CD13, CD33, CD34, HLA-DR, CD56 positive by flow cytometry analysis, were observed in the bone marrow. Myeloid/natural killer cell precursor acute leukemia was diagnosed. The remission induction chemotherapy for acute myeloblastic leukemia (AML) was performed, and complete remission was obtained. However, the size of mediastinal mass was unchanged. For attempting hematopoietic stem cell transplantation, irradiation to the mediastinal mass was performed, however, the mass did not became smaller than a half. The leukemia relapsed after 3 months, and the leukemic cells were refractory to the repeated chemotherapies, and the patient died 6 months. The autopsy findings demonstrated leukemic cells infiltration into the various organs, mediastinal mass and pulmonary alveolar proteinosis.