New York State Department of Health - Wadsworth Center - Cytohematology Proficiency Testing

Slide 152 [100X]        Click here for a higher resolution image.

Due to the presence of significant anisocytosis on this blood smear, acanthocyte (code: 30) and schistocyte (code: 39) are acceptable responses.

Schistocytes are fragments of a red blood cell, typically only one-half normal red cell volume or less. The size variation of red cells from this case makes size comparison difficult, thereby making the distinction between acanthocyte and schistocyte less clear. Schistocytes are formed when a red blood cell is caught by fibrin strands in the lumen of a blood vessel and torn. They seal their torn edges, become more dense with no central pallor, and continue in the circulation eventually to be removed by the spleen. Their presence in the peripheral smear indicates a pathological process.

Alteration of the lipid content of the red blood cell membrane results in the formation of acanthocytes. Acanthocytes have 2-20 irregular shaped membrane spikes unevenly distributed on the membrane. They appear small in number on the peripheral smear post-splenectomy and in larger amounts in cases of abetalipoproteinemia and severe liver disease.

Seven laboratories reported this cell as an echinocyte.  Echinocytes are 6.7 to 7.8 μm in diameter, the size of a normal red blood cell. The projections of the echinocyte are evenly distributed over the entire surface of the cell and range from 10 to 30 in number.

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