John Auer and Auer rods; controversies revisited.

John Auer first described needle or rod-shaped intracytoplasmic inclusion bodies in leukemia cells in 1906. Auer rods can be seen in myeloid neoplasms ranging from acute myeloid leukemias (AML) to myelodysplasia, but not in normal or non-neoplastic reactive states. This article briefly describes John Auer's experience and discusses debates on Auer rods, and criticizes their place in the definition of refractory anemia with excess of blasts-2 (RAEB-2) in the WHO classification of the myelodysplastic syndromes (MDS).