Tendon xanthomas associated with cholestanolosis and hyperapobetalipoproteinemia

Large Achilles tendon xanthomas of the type found in severe familial hypercholesterolemia were the first manifestation of cholestanolosis (cerebrotendinous xanthomatosis) in our patient, an otherwise asymptomatic normolipidemic 21-year-old woman. Extensive laboratory investigation disclosed the presence of hyperapobetalipoproteinemia which did not resolve with the administration of probucol. Immunofluorescent studies revealed marked accumulation of apolipoprotein B in a xanthoma excised from the tricipital area. This was in contrast to the spotty and weak fluorescence observed in a tuberous xanthoma, from the same anatomical area and histologically otherwise identical, obtained from a patient with heterozygous familial hypercholesterolemia. Hyperapobetalipoproteinemia has been reported before in association with sitosterolemia but not with cholestanolosis. We suggest that cholestanol, like sitosterol, may interfere with the normal uptake and degradation of low-density lipoproteins by peripheral cells.