Cerebrotendinous Xanthomatosis (CBX) is a rare lipid storage disorder, characterized by the accumulation of fats in various areas of the body. The first description of the disease was in 1937 by Van Bogaert [1]. This condition has autosomal-recessive transmission and is due to a mutation in the CYP27A1 gene [2]. The CYP27A1 encodes an enzyme – sterol 27-hydroxylase - witch breaks down cholesterol to a specific bile acid called chenodeoxycholic acid. A mutation in the CYP27A1 gene leads to a deficient break down of certain lipids, mainly different forms of cholesterol. This leads to the formation of a molecule called cholestanol witch accumulates in different areas of the organism. Serum levels of cholesterol are normal, but the concentration is elevated in various tissues of the organism [2-5]. The incidence of CBX is estimated to be 3 to 5 per 100000 people worldwide [2].

The criteria used for diagnosis include intractable diarrhea, presenile cataracts, tendinous xanthomas, and neurologic abnormalities [2-5]. The treatment of choice is with chenodeoxycholic acid, and if hypercholesterolemia is not controlled, with statins. This will slow, stop or even revers the symptoms of CTX [2].

We present the case of a 29 years old female, admitted for bilateral Achilles tendon painful swelling lasting for 6 month, loss of appetite, weight loss and memory disorders. From her medical history we noticed prolonged neonatal jaundice, surgery for bilateral cataract and chronic diarrhea during infancy.

At the physical examination she is underweight (38 Kg), with mild mental retardation, bilateral swelling of the Achilles tendon and limited dorsal flexion of the feet (Figure 1). Laboratory tests show normal serum cholesterol=138.27 mg/dl and serum cholestanol=3.6 mg/dl.

Figure 1: Bilateral swollen Achilles tendon.

Musculoskeletal ultrasound imaging identifies diffuse tendon swelling close to the calcaneal insertion. We performed Achilles tendon biopsy and the aspect foamy macrophages, cholesterol crystals, giant cells, fibrous reaction and minimal chronic inflammatory infiltrate (Figure 2). The treatment was with chenodeoxycholic acid 750 mg QD.

Figure 2: Musculoskeletal imaging with markedly swollen tendon with inhomogeneous and predominantly hypoechoic appearance.

Even if this patient presented symptoms since childhood, they were nonspecific and did not help to confirming the actual diagnosis. The delay in establishing the diagnosis and initiating therapy led to irreversible mental retardation. Data suggest that even if treatment is initiated after the onset of mental deficit, the damage is irreversible [2]. The differential diagnosis is complex and is based on the determination of serum cholestanol and biopsy. It includes hypercholesterolemia type II, leukodystrophies, xanthomas, other bile acid synthesis and conjugation disorders [2]. For the earlier diagnosis of CBX Mignarri et al proposed a suspicion index: tendon xanthomas were regarded as very strong indicators [6].