Red Blood Cell Morphology
- Page ID
- 70223
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Red blood cell morphology is always done with the 100x oil objective. Make sure to perform the red cell morphology just in from the feather edge of the smear, where the red blood cells are evenly distributed and not overlapping. The manner in which red cell morphology is reported is laboratory dependent. Some labs use specific terminology to semi-quantitate the degree of abnormal morphology such as slight/ few, moderate or marked. Other labs use a scale from 1+ to 3 or 4+.
Size and Color
Abnormal amount of variation in red cell size is termed anisocytosis. The degree of size variation is indicated by the Red Cell Distribution Width (RDW) on the CBC.
The Mean Cell Volume (MCV) indicates the average size of red blood cells present in the specimen. An increased MCV indicates that there are a significant number of macrocytes present. A decreased MCV indicates that there are a significant number of microcytes present. Beware: a normal MCV may indicate normal sized red blood cells, but since it is a mean, small and large red blood cells may average out to a normal MCV.
Microcyte
- RBC <7 microns or MCV < 80 fL
- Often accompanied by hypochromasia
- Indicator of hemoglobin production problem
- Seen in:
- Iron Deficiency
- Thalassemias
- Sideroblastic Anemias
- Anemia of Chronic Inflammation
- Some Hemoglobinopathies
Microcyte \(\PageIndex{}\)
Macrocyte
- RBC >8 microns or MCV >100 fL
- Indicator of DNA synthesis defect
- Megaloblastic changes (asynchronism)
- Seen in:
- Megaloblastic Anemias
- Oval macrocytes
- High reticulocyte count
- Hemolytic anemia
- Acute blood loss
- Diphyllobothrium latum
- Liver Disease
- Tumors
- Gastrectomy
- Bowel diseases
- Megaloblastic Anemias
Macrocyte \(\PageIndex{}\)
Hypochromasia
- RBCs lack normal amount of hemoglobin
- Increased area of central pallor
- Often microcytic
- Often MCHC < 32 g/dL
- Seen in:
- Iron Deficiency
- Thalassemias
- Sideroblastic Anemias
- Anemia of Chronic Inflammation
- Some Hemoglobinopathies
Hypochromasia \(\PageIndex{}\)
Polychromasia
- Diffuse pale blue / gray or lavender cytoplasm
- Due to remnant RNA present in young RBCs (reticulocytes)
- Often macrocytic and lack central pallor
- Can be better visualized and counted with a supravital stain that precipitates the remnant RNA
Polychromasia \(\PageIndex{}\)
Shape
Variation in red blood cell shape is termed poikilocytosis.
Acanthocyte
- Long, irregular, spiny uneven projections
- Caused by abnormal membrane lipids
- Seen in Liver disease and abetalipoproteinemia
Acanthocyte \(\PageIndex{}\)
Agglutination
- Cluster of cells at all angles
- MCHC >36 g/dL
- Due to RBC antibody
- Immune hemolytic anemias
- Cold agglutinin
- Pre-warm sample if IgM antibody
Agglutination \(\PageIndex{}\)
Burr Cell
- Small blunt evenly spaced projections
- Usually due to change in tonicity of intravascular fluid
- Seen in:
- Uremia
- Liver disease
- Anemias
- Burns
Burr Cell \(\PageIndex{}\)
Crystal Cell
- Condensation of abnormal Hgb C, often into a “Washington Monument” shaped crystal
- Hgb C disease (Hgb C-C)
- Hgb SC disease (Hgb SC)
Crystal Cell \(\PageIndex{}\)
Ovalocytosis / Elliptocytosis
- Oval or elliptical shaped with rounded ends
- Many labs do not differentiate between the two shapes
- Ovalocytes – egg shaped
- Elliptocytes – cigar or hotdog shaped
- Physiological mechanism not well defined
- Seen in:
- Hereditary Elliptocytosis
- Spectrin defect
- Iron deficiency
- Megaloblastic anemias
- Oval macrocytes
- Thalassemias
- Myelofibrosis
- Myelodysplastic syndromes
- Hereditary Elliptocytosis
Ovalocyte / Elliptocyte \(\PageIndex{}\)
Rouleaux
- Stack of coins appearance, side to side
- Increased plasma proteins or immunoglobulins
- Masks zeta potential
- Saline Replacement will dilute the proteins and disperse the rouleaux
- Seen in:
- Multiple myeloma
- Waldenstrom’s macroglobulinemia
- Infectious and Inflammatory conditions
Rouleaux \(\PageIndex{}\)
Schistocyte
- Fragmented RBCs
- Seen in:
- Hemolysis
- Disseminated Intravascular Coagulation (DIC)
- Thrombotic thrombocytopenic purpura (TTP)
- Hemolytic uremic syndrome (HUS)
- Acute promyelocytic leukemia
Schistocyte \(\PageIndex{}\)
Sickle Cell
- Due to presence of abnormal Hgb S
- In decreased oxygen tension cells will take a crescent or sickle form.
- Cells do not always form the perfect sickle shape. These cells are called oat cells. They can be differentiated from elliptocytes and ovalocytes by their tapered ends. Ovalocytes/ elliptocytes have rounded ends.
- Seen in:
- Sickle cell anemia
- Hgb SC disease
- Hgb S-Thalassemia
Sickle Cell \(\PageIndex{}\)
Spherocyte
- Small, very dark, very round
- Lack area of central pallor
- Defect in or loss of cell membrane
- Usually microcytic
- MCHC may be > 36 g/dL
- Seen in:
- Hereditary Spherocytosis
- Spectrin defect
- Hemolysis
- Burns
- Post transfusion
- Newborns
- Normal RBC aging
- Hereditary Spherocytosis
Spherocyte\(\PageIndex{}\)
Stomatocyte
- Central pallor is slot or mouth shaped
- Usually an artifact
- Seen in:
- Hereditary Stomatocytosis
- Failure of Na+ and K+ pumps which increases cellular H2O and cells swell
- Liver Disease
- Rh deficiency syndrome
- Rare hereditary defect where Rh membrane proteins are absent (Rh null) or decreased (Rh-mod) resulting in mild to moderate hemolytic anemia
- Hereditary Stomatocytosis
Stomatocyte \(\PageIndex{}\)
Target Cell
- Bullseye appearance
- Increased membrane lipid resulting in increased surface area or decreased hemoglobin
- Seen in:
- Liver disease
- Hypochromic anemias
- Any hemoglobin abnormality
Target Cell \(\PageIndex{}\)
Tear Drop
- Tear or pear-shaped cells (one tapered end)
- Exact Physiological mechanism unknown
- Altered splenic or bone marrow structure
- Removal of inclusion from RBC
- May be an artifact, especially if all pointing in the same direction
- Seen in:
- Myelofibrosis
- Myelophthisic anemia
- Megaloblastic anemia
- Thalassemias
Tear Drop \(\PageIndex{}\)
Red Cell Inclusions
Basophilic Stippling
- Fine to coarse blue dots evenly dispersed throughout cytoplasm
- Remnant precipitated RNA, reticulocyte
- Use Supravital stain to do reticulocyte count
- Coarse stippling associated with lead poisoning
Basophilic Stippling \(\PageIndex{}\)
Cabot Ring
- Very fine single or double thread loops, may be seen in ring or figure 8
- Thought to be nuclear membrane remnant
- Seen in:
- Megaloblastic anemias
- Thalassemias
Cabot Ring\(\PageIndex{}\)
Heinz Bodies (supravital stain)
- NOT visible on Wright’s stain
- Requires a Supravital Stain
- Precipitated, denatured hemoglobin due to oxidative injury
- Seen in:
- G6PD deficiency
- Unstable hemoglobins
Heinz Bodies \(\PageIndex{}\)
Hemoglobin H Inclusions (supravital stain)
- Many purple blue inclusions resembling a golf ball
- Composed of precipitated chains of beta-hemoglobin (beta 4 tetramers)
- Seen in Alpha Thalassemia
Howell-Jolly Body
- Small, dense, round nuclear remnant occurring usually singly on periphery of cell
- Busy bone marrow
- Seen in:
- Hemolytic anemias
- Megaloblastic anemias
- Thalassemias
- Splenectomy
Howell-Jolly Body\(\PageIndex{}\)
Malarial Parasites
Malaria may be present at any stage inside the RBC
Malaria \(\PageIndex{}\)
Pappenheimer Bodies
- Small, irregular, blue granules clustered near cell periphery
- Granules of Iron
- ineffective utilization or excess
- Use Prussian Blue stain to confirm
- Seen in:
- Sideroblastic anemias
- Hemochromatosis
- Hemoglobinopathies
- Thalassemias
Pappenheimer Bodies \(\PageIndex{}\)