Skip to main navigation menu Skip to main content Skip to site footer

Short communication

Vol. 140 No. 2728 (2010)

The acanthocyte-echinocyte differential

  • A Foglia
Cite this as:
Swiss Med Wkly. 2010;140:w13039


Acanthocytes are a distinct structural (and functional) entity compared to echinocytes. The differential, however, is not always clear. A summary of morphologic characteristics to make a clear distinction is provided, using the blood of a rare neurologic disease with acanthocytic transformation of red blood cells.

Chorea-acanthocytosis (ChAc) is a progressive neurodegenerative disorder correlated with a deformation of the red blood cells (RBCs) called acanthocytosis (from acantho- “thorn”, “spur cell”). ChAc is part of a clinical syndrome group called Neuroacanthocytosis syndromes (NA), first described in 1960 as “Levine-Critchley syndrome” [1]. ChAc is an autosomal recessive choreo-athetoid movement disorder with orofacial dyskinesia and dementia, while the second common clinical disorder of the same group, the McLeod syndrome(MLS), is an X-linked chronic haemolysis with chorea, peripheral neuropathy and myopathy. Other subtypes of the NA include: pantothenate kinase associated neurodegeneration(PKAN), Huntington’s disease-like 2(HDL 2) and the variant hypoprebetalipoproteinemia acanthocytosis retinitis pigmentosa pallidal degeneration syndrome(HARP) [2, 3].

Neuroanatomical changes are present in form of extensive neuronal loss and gliosis of the caudatum, the corpus striatum and the pallidum and peripheral axonal neuropathy [4, 5]. The concomitant neuronal degeneration and erythrocyte membrane abnormality may have a common proteic source [6], distinct from the lipidic source of acanthocytes of other aetiologies (M. Anderson, abetalipoproteinaemia, hypobetalipoproteinemia, alcoholic liver cirrhosis, anorexia nervosa) [7]. These abnormalities may reside on defects of the band 3 protein, involved in the regulation of the intracellular pH in neurons and major proteic component in the membrane of erythrocytes. This defect leads to disturbances in various membrane functions: anion transport, anchoring with cytoskeleton, enzyme-binding, age-related vesiculation and immune-signalling for removal of the old erythrocytes from the circulation [8].

Microscope images of peripheral blood smears, especially scanning electron microscopic ones, are reported as useful tools in investigating NA, while only genetic testing can confirm its diagnosis [4, 9, 10]. Our scanning electron microscopic investigation makes it possible to objectify the morphology of RBC in ChAc in detail, in fact the abnormality of the acanthocytic-transformed erythrocytes is very pronounced, sometimes grotesque. This is an indication that acanthocytes are a distinct structural (and functional) entity compared to echinocytes (from echino-“porcupine”, “burr cell”) [11], a differential which sometimes has been confused.

Summarizing, acanthocytes are deformed red blood cells characterised by few, irregularly distributed spikes (“spiculae”) in a blood smear where also echinocytes are present in great quantity. Echinocytes, to the other hand, are characterised by many spiculae regularly distributed on the membrane surface of the erythrocyte, mainly in blood smear without acanthocytes [7]. We could observe the presence of grotesque membrane abnormalities in acanthocytes compared to echinocytes, where the forms of the spiculae are limited to different degrees of the spiny character. Acanthocytic forms, in fact, are determined by a structural pathologic membrane defect [6, 7], whereas echinocytic forms can be caused and reversed by pH, osmolarity, biochemical and even electrical variations [12–15].

This short communication aims to make the readers aware of the potential trap which echinocytes can cause when looking for acanthocytes. This is particularly true in the case of ChAc, which diagnosis, however, relies on clinical investigations and genetic testing, in particular when light- and electron microscopy are not available.


  1. Danek A. Neuroacanthocytosis Syndromes, Springer Verlag, 2005: 5–7.
  2. Walker RH, Saiki S, Danek A. Neuroacanthocytosis Syndromes, A Current Overview. Neuroacanthocytosis Syndromes II, Springer Verlag, 2008: 3–4.
  3. Ichiba M, Nakamura M, Sano A. Neuroacanthocytosis update, Brain Nerve. 2008;60(6):635–41.
  4. Hardie RJ, Pullon HW, Harding AE, et al. Neuroacanthocytosis. A clinical, haematological and pathological study of 19 cases. Brain. 1991;114(1A):13–49.
  5. Huppertz HJ, Kröll-Seger J, Danek A, et al. Automatic striatal volumetry allows for identification of patients with chorea-acanthocytosis at single subject level. J Neural Transm. 2008;115(10):1393–400.
  6. Bosman GJ, Horstink MW, de Grip WJ. Erythrocyte membrane abnormalities in neuroacanthocytosis. Evidence for a neuron-erythrocyte axis. Neuroacanthocytosis Syndromes, Springer Verlag, 2005: 153–60.
  7. Perrin J, Georges A, Morali A, et al. Acanthocytes et hypercholesterolemia. Ann Biolo Clin. 2008;66(5):56972.
  8. Bosman GJ, De Franceschi L. Neuroacanthocytosis-related changes in erythrocyte membrane organization and function. Neuroacanthocytosis Syndromes II, Springer Verlag, 2008: 133–42.
  9. Marson AM, Bucciantini E, Gentile E, Geda C. Neuroacanthocytosis: clinical, radiological and neurophysiological findings in an Italian family, Neurol Sci. 2003;24(3):188–9.
  10. Galey WR, Evan AP, Van Nice PS, et al. Morphology and physiology of the McLeod erythrocyte. I. Scanning electron microscopy and electrolyte and water transport properties. Vox Sang. 1978;34(3):152–61.
  11. Lichtman M, Bentler E, Kipps TJ, et al. Williams Hematology, 7th ed., McGraw-Hill, 2005:369–82.
  12. Reinhart WH, Chien S. Red Cell Rheology in Stomatocyte-Echinocyte Transformation: Roles of Cell Geometry and Cell Shape. Blood. 1986;4:1110–8.
  13. Wong P. A Basis of Echinocytosis and Stomatocytosis in the Disc-sphere Transformations of the Erythrocyte, J Theor Biol. 1999;196(3):343–61.
  14. Mrowietz C, Hiebl B, Franke RP, et al. Reversibility of Echinocyte Formation after Contact of erythrocytes with various Radiographic Contrast Media. Clin Hemorheol Microcirc. 2008;39(1–4):281–6.
  15. Schwarz S, Deuticke B, Haest CW. Passive Transmembrane Redistributions of Phospholipids as a Determinant of Erythrocyte Shape Change. Studies on Electroporated Cells. Mol Membr Biol. 1999;16(3):247–55.
  16. O’Connor BH. A Color Atlas and Instruction Manual of Peripheral Blood Cell Morphology, William & Wilkins, 1984: 3–5.