acanthocytosis

Acanthocytosis refers to the presence of acanthocytes, abnormally spiculated red blood cells with irregular, thorn-like projections on their membranes. Acanthocytes, also called spur cells, are seen on a peripheral blood smear and can occur in a range of disease states. They are not specific to a single disorder but are a classic finding in several conditions, particularly neuroacanthocytosis syndromes and liver disease.

Causes and associations include neuroacanthocytosis disorders such as chorea-acanthocytosis, caused by mutations in the VPS13A gene, and McLeod syndrome, due to XK gene mutations. These conditions feature movement disorders, cognitive or psychiatric symptoms, and acanthocytosis. Acanthocytosis is also described in abetalipoproteinemia (apolipoprotein B deficiency) and in severe liver disease (including cirrhosis and alcoholic liver disease), as well as in severe malnutrition or vitamin deficiencies. Less commonly, acanthocytosis can be acquired in other lipid disorders or after splenectomy.

Pathophysiology involves alterations in red blood cell membrane composition. In liver disease, changes in circulating lipids and lipoproteins can modify the membrane, increasing the cholesterol-to-phospholipid ratio and disrupting membrane stability, leading to spiculated shapes. In genetic neuroacanthocytosis syndromes, mutations affect membrane proteins, contributing to abnormal red blood cell morphology.

Diagnosis relies on identification of acanthocytes on peripheral smear, with differential including echinocytes. Confirmation is aided by clinical context and genetic testing for VPS13A and XK mutations, as well as evaluation for underlying liver disease or abetalipoproteinemia through lipid profiles and related tests.

Treatment targets the underlying condition and symptoms; there is no specific therapy to reverse acanthocytosis. In neuroacanthocytosis, management is multidisciplinary, focusing on movement disorder medications, psychiatric support, and supportive care. Prognosis varies by condition and its progression.