An 11-year-old boy with familial hypercholesterolemia showing multiple xanthomas and advanced atherosclerosis, who responded to lipid-lowering therapy using statin.

Familial hypercholesterolemia (FH) is characterized by a high level of LDL-cholesterol (LDL-C) and a high prevalence of atherosclerotic coronary heart disease; however, hypercholesterolemia is usually the only clinical finding in children with heterozygous FH in their first decade of life. We report a case of FH in an 11-year-old boy who presented with multiple xanthomas at both elbows, thickened Achilles tendons, and hyperplasia of the intima-media complex of the carotid artery. Echocardiogram revealed partial calcification of the aortic and mitral valves, but no stenosis of the coronary arteries was detected on 3D-computed tomography. The activity of LDL receptors was reduced to 32% by lymphocyte assay. The family history showed vertical transmission of hypercholesterolemia from father to son, thereby suggesting dominant inheritance. After 12 months of treatment with statin and resin, his LDL-C decreased from 446 to 220 mg/dL, thickening of the Achilles tendons decreased from 1618 mm to 13 mm, and hyperplasia of the intima-media complex decreased from 1.3 mm to 0.7 mm. These findings suggest that our patient had heterozygous FH. However, based on his advanced atherosclerosis, we cannot exclude the possibility that our patient may be accompanying dyslipidemia due to causes in addition to heterozygous FH.