E-Table 13-1.
Common Erythrocyte Morphologic Abnormalities
| Term | Description | Common Causes or Conditions |
|---|---|---|
| Macrocyte | Abnormally large | Regenerative anemia Feline leukemia virus infection (cats) Congenital in some poodle dogs |
| Microcyte | Abnormally small | Iron deficiency Portosystemic shunts Normal in Akita and Shiba dogs |
| Polychromasia | Bluish color (see Figs. 13-5 and 13-8) | Reticulocytosis (erythroid hyperplasia) |
| Basophilic stippling | Fine punctate inclusions (see Fig. 13-8) | Lead toxicity Regenerative anemia (especially ruminants) |
| Howell-Jolly body | Small, round, blue-black inclusion, usually off center (see Fig. 13-15) | Regenerative anemia Splenic dysfunction Congenital in some poodle dogs |
| Hypochromasia | Increased central pallor (see Fig. 13-15) | Iron deficiency |
| Heinz body | Pale round inclusion, may bulge from cell margin; stains blue with new methylene blue (see Fig. 13-14) | Oxidative damage |
| Poikilocyte | Nonspecific term for shape abnormality—specific types of poikilocytosis listed below | See below |
| Spherocyte | Appears abnormally small with uniform staining (see Fig. 13-13) | Extravascular hemolysis |
| Schistocyte | Small, irregular RBC fragment, often crescent shaped (see Fig. 13-15) | Microangiopathies (e.g., disseminated intravascular coagulation, hemangiosarcoma, vasculitis) Increased fragility (e.g., iron deficiency) |
| Acanthocyte | Few irregular projections (see Fig. 13-15) | Abnormal lipid metabolism (e.g., liver disease) Microangiopathies (as per schistocytes) Increased fragility (as per schistocytes) Common normal finding in young goats |
| Echinocyte | Many relatively uniform projections (see Fig. 13-15) | Usually in vitro artifact Normal in pigs Some envenomations |
| Eccentrocyte | Eccentric staining (see Fig. 13-15) | Oxidative damage |
| Leptocyte | Thin, often hypochromic and/or folded | Reticulocytosis Iron deficiency |
| Codocyte (“target cell”) | Type of leptocyte with area of dense staining within central pallor (see Fig. 13-15) | Reticulocytosis Liver disease |
| Keratocyte | Intact or ruptured “blister” (see Fig. 13-15) | Conditions causing schistocytosis and/or acanthocytosis |
| Stomatocyte | Type of leptocyte with linear central pallor | Reticulocytosis |
RBC, Red blood cell.