Muscle CT scan findings in McLeod syndrome and chorea-acanthocytosis.

Computed tomography (CT) scans of lower leg muscles reveal a selective pattern of fat infiltration in the posterior compartment with spared gracilis, semitendinosus, and the lateral head of the gastrocnemius in both McLeod syndrome and chorea-acanthocytosis, which are disorders characterized by the presence of circulating acanthocytes. The selectivity of affected muscles indicates that late onset and slowly progressive muscular atrophy in both diseases could be a consequence of primary myopathy. Asymmetrical muscle involvement may be seen during the process of degeneration only in McLeod syndrome, however, and may be helpful in distinguishing this disease from chorea-acanthocytosis.