|Red cell shape abnormality||Elliptocyte|
|Also known as||Ovalocyte|
|Definition||Small or normal sized red cells that have an elongated appearance. Usually contain central pallor. The ends of the cells are blunt and not sharp like sickle cells.|
|Types||1) Classical elliptocytes: sides are parallel, with long axis > 2x short axis. Large numbers may be seen in hereditary elliptocytosis.|
2) Ovalocytes: egg-shaped red cells with long axis < 2x short axis. Large numbers may be seen in hereditary elliptocytosis.
3) Rod-shaped cells (pencil cells): elliptocytes with long axis more than 3 times the length of the short axis. Large numbers may be seen in hereditary elliptocytosis and severe iron deficiency.
|Conditions associated with the shape abnormality||Hereditary elliptocytosis (% of elliptocytes 10-100%), thalassemia, iron deficiency. Rare elliptocytes (less than 1%) may be seen on a normal peripheral smear.|
|Mechanism of formation||Hereditary elliptocytosis is caused by hereditary membrane protein defects especially involving defective horizontal interactions in the membrane cytoskeleton.|
|History||According to Davidson and Strauss, writing in 1961: “The first record of elliptical human red corpuscles is usually credited to Dresbach (1904) but Lambrecht (1938) states that the anomaly was observed in 1860 by Goltz.” J Clin Pathol. 1961;14:615-2.|