Acanthocytes (Spur Cells)

By William Aird

Multiple acanthocytes (one shown in square and magnified in inset) in a 77-year-old man with alcoholic cirrhosis. Note the thorn-like projections of variable size/length/thickness, the uneven distance between projections, and the absence of central pallor (100x, oil).

Peripheral smear from a 77-year-old man with alcoholic cirrhosis shows multiple acanthocytes (50x).

Multiple acanthocytes in a 56-year-old woman with cirrhosis. N, neutrophil; L, lymphocyte (100x, oil).

Multiple acanthocytes in a 49-year-old man with cirrhosis. Boxed cell is shown at higher magnification in inset (100x, oil).
Red blood cell, shape abnormalityAcanthocyte
Also known asSpur cells from the Greek acantha “thorn“ (some have advocated restricting the term acanthocyte for those with hereditary neurological syndromes, and spur cell for the remainder of cases).
DefinitionAcanthocytes are densely stained, spheroidal red blood cells that lack central pallor and have 3-20 irregularly distributed, thorn-like projections of variable size/length/thickness, often with drumstick (knobby) ends. Spicules may occasionally have branches.
DdxMust be differentiated from burr cells. Small contracted cells in pyruvate kinase have the appearance of acanthocytes but they do not carry that name.
Conditions associated with the shape abnormality Hereditary abetalipoproteinemia (hereditary acanthocytosis), McLeod syndrome/phenotype and chorea-acanthocytosis; severe end-stage liver disease, post splenectomy, hypothyroidism, anorexia nervosa, and chronic starvation.
Mechanism of formationMembrane defect associated with increased RBC cholesterol with reduction in other major phospholipids and decreased cholesterol: PL ratio. Imbalance in cholesterol and PL leads to preferential expansion of the outer leaflet of lipid bilayer. Mechanism probably differs in abetalipoproteinemia, where lack of a structural protein plays a role.
HistoryFirst described in 1950 by Bassen and Kornzweig; named in 1952 by K. Singer. Spur cell anemia first reported in 1964.
Source/authorWilliam Aird
Reviewed and edited byParul Bhargava