Usually, seeing an Auer rod means that you're looking at a case of acute myeloid leukemia (AML). In fact, for many years, Auer rods were considered virtually diagnostic of AML. ... Auer rods are seen in several (but not all!) types of AML.

Do all AML have Auer rods?

Auer rods are a hallmark of acute myeloid leukemia but occasionally are seen in myelodysplastic syndromes (MDSs) or chronic myelomonocytic leukemia, rarely in cases with fewer than 5% blasts. The significance of this finding is unclear. We report 9 cases of this unusual phenomenon.

Where can Auer rods be found?

Auer rods are cytoplasmic inclusions found only in the leukaemic cells of some cases of acute myeloid leukaemia (AML).