Leptomeningeal disease in pre-leukemic syndrome: cytogenetic abnormality versus cellular morphology

Refractory anemia with excess blasts in transformation (RAEB-T) is a pre-leukemic syndrome that can progress to acute myelogenous leukemia (AML). Although leptomeningeal disease in AML is rare and it is commonly associated with specific cytogenetic abnormalities, it has not been documented in RAEB-T. We report a woman who experienced seizures and had subarachnoid enhancement on MRI suggestive of leukemic infiltrates in the leptomeninges. Her bone marrow aspirate revealed 6.6% blasts and the presence of Auer rods, findings consistent with a diagnosis of RAEB-T. Subsequent cytogenetic analysis detected an uncommon deletion of chromosome 11q23, and the breakpoint on chromosome 11 is identical to that seen in AML patients having leptomeningeal disease and translocation between chromosome 9 and 11. Although RAEB-T is not considered as leukemia and is thought unlikely to involve the central nervous system, the presence of leptomeningeal disease and 11q23 deletion in our patient suggests that cytogenetic abnormality may be an important determinant of neurological complications, regardless of a diagnosis of RAEB-T or AML which is based on cellular morphology.