Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Abnormal

Promyelocyte with Auer Rods*

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Microscopic Features:
  • 3-4x larger than a mature RBC
  • High nuclear to cytoplasmic (N/C) ratio
  • Round Nucleus with immature chromatin (not clumped)
  • Prominent nucleoli
  • Cytoplasm is not as scant as a myeloblast, gray to pale blue with primary granules
  • Multiple Auer rods may be seen as well
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 Promyelocytic Leukemia (APL)

Classic Immunophenotype:
  • CD34-
  • CD117+
  • HLA-DR-
  • CD13+
  • CD33+
  • (they may have immunophenotypic aberrancies such as gain of CD56, etc.)
Cartoon Image:

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for direct comparison

  • Promyelocyte with multiple Auer rods are called a "Faggot cell" (Faggot meaning "Bundle of Sticks," the numerous auer rods resemble such).

Content Editors/Website Administrators:
Hooman H. Rashidi, MD; John C. Nguyen, MD