Erythrocytes - Color

Hypochromia

  • Red Cells with low concentrations of hemoglobin resulting in a central pallor of more than a third of the cell diameter are said to be hypochromatic
 

Hyperchromia

  • Deeply staining red cells lacking the central pallor are said to be hyperchromatic.
 

Polychromasia

  • Red cells showing a blue or lilac color are termed to be polychromatic (showing many colors). Young red cells released into the peripheral blood as a consequence of increased production are larger than mature erythrocytes and more basophilic on staining.
 

Erythrocytes - Shape

Poikilocytosis

  • A large variation in shape of the erythrocytes is called poikilocytosis
 

Spherocytes

  • Red cells with a loss of membrane leading to reduced diameter and decreased surface area but normal volume are called spherocytes. They are seen in hereditary spherocytosis, erythroblastosis and acquired hemolytic anemias.
 

Elliptocytes/Ovalocytes

  • Red cells varying in shape from elongated to oval, and rich in hemoglobin, are called elliptocytes/ovalocytes. They can be seen in hereditary disorders, such as hereditary elliptocytosis, or in acquired disorders, such as iron defiency anemia, infectious anemias, thalassemia, and in newborn babies.
 

Stomatocytes

  • Erythrocytes with a loosely folded, mouth-like pale area across the cell are called stomatocytes. They are seen in hereditary stomatocytosis, lead poisoning and thalassemia trait.
 

Schistocytes

  • Fragmented cells showing bizarre poikilocytosis are called schistocytes. They can be seen in various forms of microangiopathic hemolytic anemia as well as after injury by mechanical means, e.g. through cardiac valve prostheses.
 

Keratocytes

  • Schistocytes having one or more large horns around the perimeter are called keratocytes.
 

Helmet Cells

  • These are sharp-angled, helmet-looking cells seen in various anemias, e. g. thalassemia.
 

Acanthocytes

  • Spherocytical cells with large irregularly placed protrusions are called acanthocytes.
 

Echinocytes

  • Red cells exposed to a hypertonic medium become wrinkled (crenated) with many small knoblike projections. They are called echinocytes.
 

Target Cells

  • Target cells, also known as Codocytes, have the hemoglobin concentrated in the middle and the periphery of the cell, and thereby resemble targets. They can be seen in hemoglobinopathies, e.g. thalassemias, and iron deficiency anemia.
 

Tear Drop Cells

  • Tear drop shaped red cells are also called Dacryocytes. They are seen when there is extramedullary erythropoiesis or with marrow disorders or marrow infiltration, such as myelofibrosis or metastatic carcinoma.
 

Sickle Cells

  • Sickle shaped cells are also called Drepanocytes. These cells take on a sickle-like appearance due to low oxygen tension. They are typically seen with hemoglobin S (sickle cell anemia).
 

Degmacytes

  • As a result of losing a portion of the cell perimeter, these cells take on a bite-like appearance and are called degmacytes. They are seen in drug-induced hemolysis.
 

Erythrocytes - Size

Normocytes

  • Erythrocytes normally show very little variation in size, having a diameter around 7-8 microns.
 

Anisocytosis

  • A large variation in size of the erythrocytes is called anisocytosis
 

Microcytes

  • Erythrocytes smaller than 6.5 microns are called microcytes. They can be seen in iron deficiency anemia.
 

Macrocytes

  • Erythrocytes larger than 8.5 microns in diameter are called macrocytes. They are thicker and stain deeper than normocytes. They are found in megaloblastic anemias and aplastic anemia among others. Hemolysis can result in the appearance of immature red cells in peripheral blood, e.g. polychromatic macrocytes, due to increased production. For the same reason, hypochromatic macrocytes can be seen in thalassemia minor.
 

Megalocytes

  • Megalocytes are oval-shaped Macrocytes that are seen in megaloblastic anemias