AJR:170, March 1998 621 Sonographic Detection of Xanthomas in Normal-Sized Achilles’ Tendons of Individuals with Heterozygous Familial Hypercholesterolemia Ronald 0. Bude1 Shawna 0. Nesbitt2 Ronald S. Adler1 Melvyn Rubenfire2 OBJECTIVE.The objective ofthis study was to evaluate how well high-frequency linear array sonography reveals xanthomas in the Achilles’ tendons of individuals with heterozygous familial hypercholesterolemia before the xanthomas enlarge the tendons enough to become palpable. SUBJECTS AND METHODS. Both Achilles’ tendons of 23 individuals (I8 female and five male; age range, 16-69 years old) who had heterozygous familial hypercholesterolemia but no clinically apparent Achilles’ tendon xanthomas were studied with high-frequency linear ar- ray sonography. Hypoechoic areas, consistent with xanthomas, were noted. RESULTS. Xanthomas were revealed in 36 (78%) of46 tendons and 19 (83%) of23 individuals. CONCLUSION. Sonography reveals Achilles’ tendon xanthomas in many individuals with heterozygous familial hypercholesterolemia before the xanthomas are clinically apparent. Because tendon xanthomas in a hypercholesterolemic individual are essentially pathognomonic of hetero- zygous familial hypercholesterolemia and are a mainstay in its diagnosis, our study suggests that sonography is useful in the early diagnosis of heterozygous familial hypercholesterolemia. Received July 3, 1997; accepted after revision September 17, 1997. Supported in part by a grant from the American Heart Association. 1Department of Radiology, university of Michigan Medical School, Taubman Center 2910K, 1500 E. Medical Center Dr., Ann Arbor, Ml 48109-0326. Address correspondence to RD. Bude. 2Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Ml 48109. AJR 1998;170:621-625 0361-803X/98/1703-621 © American Roentgen Ray Society D ifferentiating heterozygous famil- ial hypercholesterolemia from the other severe forms of hypercholes- terolemia-familial combined hyperlipidemia and polygenic hypercholesterolemia-has both clinical and therapeutic implications. Not only is the hypercholesterolemia of heterozy- gous familial hypercholesterolemia harder to treat than that of familial combined hyperlipi- demia and polygenic hypercholesterolemia, but also family members need to be screened for this inherited disorder. Distinguishing het- erozygous familial hypercholesterolemia from familial combined hyperlipidemia and poly- genic hypercholesterolemia is often not possi- ble by standard clinical criteria. Heterozygous familial hypercholesterolemia is an autosomal dominant disorder with a prevalence of approximately one in 500 [ I , 21. Abnormal or absent low-density lipoprotein receptors cause the accumulation of choles- terol-rich low-density lipoprotein particles. Total cholesterol levels range from 270 to 550 mg/dl (6.98-14.22 mmolll), with corre- sponding elevations of low-density lipopro- tein cholesterol [3]. Cholesterol levels in heterozygous familial hypercholesterolemia overlap considerably with those in polygenic hypercholesterolemia and familial combined hyperlipidemia, which together are approxi- mately 20 times more common than heterozy- gous familial hypercholesterolemia [41. Heterozygous familial hypercholesterolemia is characterized by an autosomal dominant in- heritance pattern and the formation of exten- sor tendon xanthomas, and the presence of one of these characteristics in addition to hy- percholesterolemia is usually needed to estab- lish the diagnosis. In fact. the presence of Achilles’ tendon xanthomas is essentially pa- thognomonic of heterozygous familial hyper- cholesterolemia [ I I. However. family histories are often unreliable and cannot be used to document the autosomal dominant inheritance pattern. Furthermore. xanthomas are not pal- pable in approximately 257c ofadults 131. Es- tablishing the diagnosis of heterozygous familial hypercholesterolemia is therefore cx- tremely difficult in many affected individuals whose tendons feel normal on palpation. The ideal tool for detecting heterozygous familial hypercholesterolemia in persons without easily palpable tendon xanthomas would be sensitive. highly specific (i.e., a very low false-positive rate), reproducible, widely available, and relatively inexpensive. The only tests currently available with high sensitivity and specificity for heterozygous Downloaded from www.ajronline.org by 54.162.69.248 on 05/26/20 from IP address 54.162.69.248. Copyright ARRS. For personal use only; all rights reserved