[Near-tetraploidy acute myeloid leukemia with RUNX1-RUNX1T1 rearrangement due to cryptic t(8;21)].

Tetraploidy or near-tetraploidy is a rare cytogenetic abnormality found in AML, and is divided into primary and secondary forms. The secondary tetraploidy or near-tetraploidy found in AML is known to be specifically associated with t(8;21). In this case report, FISH analysis detected RUNX1-RUNX1T1 gene rearrangement in the absence of cytogenetic abnormality of t(8;21), which suggests the presence of unvailed t(8;21). This is the first case report of tetraploidy or near-tetraploidy AML with cryptic RUNX1/RUNX1T1 in Korea. Although the prognosis of tetraploidy or near- tetraploidy with t(8;21) is known to be poor, this patient shows a relatively good clinical course compared to other reported cases.