[Xanthomas of the Achilles tendon as the cardinal symptom of sitolsterolemia].

The circumference of both Achilles tendons had gradually increased over the years in a now 32-year-old man (diameter of the left tendon 4.5 cm, of the right one 3.5 cm). This finally led to exercise-related pain in both tendons. Biopsy revealed benign deposition of xanthomata. Serum total cholesterol concentration was 261 mg/dl. Determination of various sitosterol fragments in serum gave a beta-sitosterol level of 43 mg/dl (normal range 0.3-1.7 mg/dl), characteristic of sitosterolaemia, which is an autosomal recessive disease causing intestinal hyperabsorption of a range of plant steroids closely related to cholesterol. On a diet low in plant steroids and treatment with cholestyramine (up to 32 g daily) the beta-sitosterol concentration fell, but only to 35 mg/dl, because of poor patient compliance. The patient died suddenly from coronary artery stenosis seven months after the diagnosis of sitosterolaemia.