Multiple tendon xanthomas in a child with familial hypercholesterolaemia

Clinical History

A 10-year-old boy presented with the complaint of gradually progressing swelling around the right knee for 1 year. On physical examination, the quadriceps and patellar tendon of the right knee were bulky. Thickening was also noted in quadriceps and patellar tendon of left knee and bilateral achilles tendons.

Imaging Findings

Ultrasonography with panoramic imaging of extensor tendons of bilateral knee and bilateral achilles tendons was performed.

Diffuse fusiform thickening of the tendons was noted with loss of normal fibrillary architecture. There was loss of concavity of the inner margins of both achilles tendons with convex inner margins. The affected tendons show heterogeneous nodular architecture.
Bilateral elbows, hands and wrists were also evaluated by ultrasound but did not reveal any abnormality.

Imaging features were suggestive of multiple tendon xanthomas and hence, lipid profile was advised. The serum cholesterol, serum Low Density Lipoprotein (LDL) cholesterol and serum triglycerides were 894mg/dl, 619mg/dl and 184mg/dl respectively.

Fine needle aspiration cytology from achilles tendon was done and was diagnostic of xanthoma.

Discussion

Xanthomas are small lumps located in the skin or subcutaneous tissue that consist of cholesterol, cholesterol esters, triglycerides, phospholipids and numerous lipid-laden foamy macrophages. The most frequent site is the achilles tendon [1]. Xanthomas are commonly seen in familial hyperlipidaemias type 2 and 3, but could also be associated with non-familial hypercholesterolaemia, drug-induced hypercholesterolaemia and cerebrotendinous xanthomatosis [2]. As the xanthomas enlarge, they can cause pain, restricted joint mobility, disability, and tendon rupture [3, 4].

Xanthomas may precede the diagnosis of hyperlipidaemia, hence early identification can lead to preventative treatment that reduces the risk and morbidity of cardiovascular disease, including myocardial infarction.

Although physical examination may reveal achilles tendon xanthomas, there are several imaging methods for their detection with ultrasonography being the method of choice in everyday clinical practice. Normal sonographic appearance of tendons is characterised by multiple parallel linear echoes that give a fibrillar pattern. Xanthomas have been described either as hypoechoic nodules or as having a diffusely heterogeneous echo pattern at sonography [1]. Partial tendon tears or tendinitis may present a similar appearance and may cause wrong diagnosis. In our patient, sonography revealed diffuse fusiform thickening of tendons of knee and ankle with altered echotexture and multiple hypoechoic nodules.

MRI of the tendon xanthomas demonstrates morphological and signal intensity abnormalities. When a xanthoma is present, the normally flat or concave margins of tendons may change and may have a convex appearance on axial images. Also, the tendons tend to have higher signal intensity on T1-weighted and T2-weighted spin-echo images than normal tendons do [5, 6].

Although several treatments for achilles tendon xanthomas have been proposed, they target mostly the treatment of the basic metabolic disorder of lipid metabolism, which is the main cause of these lesions. Surgery is reserved for larger lesions, often associated with symptoms.

Differential Diagnosis List

Final Diagnosis

Multiple tendon xanthomas in a child with familial hypercholesterolaemia

URL:	https://www.eurorad.org/case/13737
DOI:	10.1594/EURORAD/CASE.13737
ISSN:	1563-4086