Trisomy 10 in a Child with Acute Nonlymphocytic Leukemia Followed by Relapse with a Different Clone

We report a 2-year-old Japanese boy with acute nonlymphocytic leukemia (ANLL) having trisomy 10 as the sole chromosomal abnormality. The majority of the marrow blasts had lobulated nuclei and Auer rods in their cytoplasm. The blasts were positive for peroxidase, CD13, CD15, and CD33, but negative for esterase, CD3, CD7, CD34, and HLA-DR, indicating a diagnosis of ANLL, atypical M2 in French-American-British (FAB) classification. He was treated with combination chemotherapy, including anthracyclines, etoposide, and cytosine arabinoside. Four months after achieving the first remission, the disease relapsed during the consolidation therapy, and he died 9 months later. Trisomy 10 was not detected at relapse, and blasts showed phenotypes different from those at initial diagnosis. The present case suggests that the prognosis of acute leukemia with trisomy 10 in the pediatric age group may not be good, and that further studies are required to clarify the association of trisomy 10 with leukemogenesis and disease progression.