Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Myeloid ›› Granulocytes & Precursors ›› Abnormal
Myeloblast with Auer Rod
›Microscopic Features:
- 3-4x larger than a mature RBC
- High nuclear to cytoplasmic ratio
- Round Nucleus with immature chromatin (not clumped)
- Prominent nucleoli
- Cytoplasm is scant, gray to pale blue and usually lacks granules
- One or more red-pink rod shaped structures called Auer rod(s) are noted in the cytoplasm
›Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
- PB: None
- BM: None
- LN: None
›May Resemble:
›Differential Diagnoses:
If in blood or in bone marrow:
Acute myeloid leukemia (AML)
Myelodysplastic Syndromes (specifically RAEB-II)
Acute myeloid leukemia (AML)
Myelodysplastic Syndromes (specifically RAEB-II)
›Classic Immunophenotype:
- CD34+
- CD117+
- HLA-DR+
- CD13+
- CD33+
- (they may have immunophenotypic aberrancies such as gain of CD56 or CD7, etc.)
›Cartoon Image:
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›Misc:
Presence of Auer rod is diagnostic of the blasts' Myeloid origin (the only morphologic feature that could reliably distinguish a myeloblast from a lymphoblast) . Note: Other blasts (e.g. lymphoblasts) lack Auer rods