Sea-blue histiocytosis in a patient with acute myeloid leukemia with myelodysplasia-related changes harboring isolated trisomy 9: pathognomonic or a coincidence?

Although isolated trisomy 9, a form of chromosome aneuploidy, is rare in acute myeloid leukemia (AML), up to 30 cases of AML involving isolated trisomy 9 have been reported to date. We report the case of a 77-year-old female with AML, in which trisomy 9 was detected as an isolated aberration. In addition, the patient's bone marrow displayed so-called sea-blue histiocytosis. The accumulation of further cases of isolated trisomy 9-harboring AML involving sea-blue histiocytosis is necessary to determine whether the coexistence of these findings is pathognomonic or a coincidence.