Overview
Immature granulocytes, such as band forms, metamyelocytes, myelocytes and promyelocytes, are not usually seen in peripheral blood.
Stages of Neutrophil Development
- Myeloblast
- Promyelocyte
- Myelocyte
- Metamyelocyte
- Banded neutrophil (<8% normally) - U-shaped nucleus
- Mature neutrophil - 3-5 nuclear lobes
Left Shift of Granulocytes
Left shift refers to the presence of neutrophil precursors in the circulation. This may be an increase in band forms or the presence of any metamyelocytes, myelocytes or promyelocytes.
This may be physiologic in response to a stress on the body such as pregnancy, infection or inflammation; it may occur with administration of granulocyte colony stimulating factor (G-CSF); or it may be a sign of bone marrow infiltration.
Causes of Left Shift of Granulocytes
- Pregnancy
- Infection / inflammation
- G-CSF administration
- Bone marrow infiltration - MPNS, leukaemias, lymphomas, myeloma, metastatic cancer
The presence of nucleated red blood cells and left shift is referred to as a leukoerythroblastic blood film. If left shift is present then look for nucleated red cells.
Examples
- A metamyelocyte. : Note the kidney-shaped nucleus and intracytoplasmic granules. This metamyelocyte is hypergranular.
![A metamyelocyte. Note the kidney-shaped nucleus and intracytoplasmic granules. This metamyelocyte is hypergranular.]()
- A myelocyte. Note the ovoid nucleus that is eccentric (to one side of the cell).
![A myelocyte. Note the ovoid nucleus that is eccentric (to one side of the cell).]()
- A promyelocyte. Note the basophilic cytoplasm, prominent nucleolus, prominent intracytoplasmic granules and the perinuclear clearing (the light area adjacent to the nucleus).
![A promyelocyte. Note the basophilic cytoplasm, prominent nucleolus, prominent intracytoplasmic granules and the perinuclear clearing (the light area adjacent to the nucleus).]()
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