2.7: Elliptocytes and Ovalocytes

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: A peripheral blood smear with numerous elliptocytes present. 100x magnification. From MLS Collection, University of Alberta, https://doi.org/10.7939/R35H7C887

: A peripheral blood smear showing elliptocytes along with various other poikilocytosis. 50x oil immersion. From MLS Collection, University of Alberta, https://doi.org/10.7939/R3H98ZV4C

Cell Description:

Elliptocytes: Red blood cells are cigar or pencil shaped with parallel sides and an area of pallor.^1,2

Ovalocytes: Are red blood cells that are oval or egg shaped.^1,2

Macro-ovalocytes: Ovalocytes that are larger than a normal red blood cells.³

Southeast Asian Ovaloctyes: Ovalocytes show two transverse zones of pallor separated by a transverse zone of cytoplasm.⁴

Cell Formation:

Elliptocytes and ovalocytes are formed only after the red blood cell has reached its normal and mature morphology. Elliptical features develop over time as the cell undergoes stress in the circulation.^1,2

Formation occurs due to erythrocyte membrane protein defects resulting in an increase in mechanical weakness and membrane fragility.^1,3,5

Hereditary elliptocytosis occurs due to defects in the horizontal protein linkages between the membrane and cytoskeleton. (α-spectrin, 𝛣-spectrin, protein 4.1, glycophorin C).^5,6

Associated Disease/Clinical States: ^1,4,7

Elliptocytes:

Hereditary elliptocytosis

Thalassemia

Iron deficiency Anemia

Ovalocytes:

Hereditary ovalocytosis (Southeast Asian Ovalocytosis)

Megaloblastic Anemia (Macro-ovalocytes)

References:

1. Landis-Piwowar K, Landis J, Keila P. The complete blood count and peripheral blood smear evaluation. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 154-77.

2. Manchanda N. Anemias: red blood morphology and approach to diagnosis. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 284-96.

3. Jones KW. Evaluation of cell morphology and introduction to platelet and white blood cell morphology. In: Clinical hematology and fundamentals of hemostasis. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 93-116.

4. Ford J. Red blood cell morphology. Int J Lab Hematol [Internet]. 2013 Mar 9 [cited 2018 Jul 12];35(3):351–7. Available from: https://doi.org/10.1111/ijlh.12082

5. Gallagher PG. Abnormalities of the erythrocyte membrane. Pediatr Clin North Am [Internet]. 2013 Dec 15[cited 2018 Jun 26];;60(6):1349–62. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4155395/

6. Da Costa L, Galimand J, Fenneteau O, Mohandas N. Hereditary spherocytosis, elliptocytosis, and other red cell membrane disorders. Blood Rev [Internet]. 2013[cited 2018 Jul 24];27(4):167–78. Available from: http://www.sciencedirect.com/science/article/pii/S0268960X13000192

7. Rodak BF, Carr JH. Variations in shape and distribution of erythrocytes. In: Clinical hematology atlas. 5th ed. St. Louis, Missouri: Elsevier Inc.; 2017. p. 93-106.