RBC variations in shape are listed in the tables below along with associated conditions. The morphological variations in red blood cell shape shown in Table 1 have clinical significance, even in low numbers, and should be identified and reported regardless of the frequency of observation on the smear.
Table 1. Common Variations of Red Blood Cells. Other morphological variations in red blood cell shape have little significance when seen in very low numbers and are clinically relevant when their presence is more obvious. These variations in shape that are significant only if observed in large numbers on the smear are listed in Table 2.
Table 2. Uncommon Variations of Red Blood Cells.| Cell Name | Image | Possible Significance (in large numbers) |
| Echinocyte (Burr cell) |  | Anemia |
| Elliptocytes / ovalocytes |  | Hereditary elliptocytosis |
| Stomatocytes |  | Hereditary stomatocytosis, acquired hemolytic anemias |
| Target cells (Codocytes) |  | Thalassemia, retention jaundice |
