Auer rod

Auer rods (or Auer bodies) are large, crystalline cytoplasmic inclusion bodies sometimes observed in myeloid blast cells during acute myeloid leukemia, acute promyelocytic leukemia, high-grade myelodysplastic syndromes and myeloproliferative disorders. Composed of fused lysosomes and rich in lysosomal enzymes, Auer rods are azurophilic and can resemble needles, commas, diamonds, rectangles, corkscrews, or (rarely) granules.^[1]

Myeloblast with an Auer rod (to the left of the nucleus).

Eponym

Although Auer rods are named for American physiologist John Auer,^[2] they were first described in 1905 by Canadian physician Thomas McCrae, then at Johns Hopkins Hospital,^[3] as Auer himself acknowledged in his 1906 paper. Both McCrae and Auer mistakenly thought that the cells containing the rods were lymphoblasts.^[4]

Additional images

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  Bone marrow aspirate showing acute myeloid leukemia with Auer rods in several blasts
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