The patient is a 28-year-old man with no previous pertinent medical, surgical, or family history, specifically hyperlipidemia. He presented with pain and a slow-growing swelling above the right heel. There was also no history of trauma in this area.
Magnetic resonance imaging (MRI) was performed, which included T1 and T2 with fat suppression sequences in sagittal and axial planes.
Images showed a focal thickening of Achilles tendon, with loss of its normal anterior concavity. The tendon had heterogeneous signal intensity, and a diffuse “stippled” pattern, displaying higher signal intensity on both T1 and T2 images than normal. There were also some areas of pronounced hyperintensity on T2.
Surgical biopsy was performed. Grossly, the lesion presented as a lobulated shiny yellow-tan soft-tissue mass separated by thin gray septa, infiltrating the Achilles tendon. Microscopic analysis revealed foamy histiocytes and reactive giant cells around cholesterol crystals, interspersed among the normal tendon bundles, with a tendency to cavitation in the centre, which could explain the pronounced hyperintense areas on T2 images. The pathologic diagnosis was xanthoma of Achilles tendon.
Xanthomas are non-neoplastic lesions characterised by accumulation of lipid-laden macrophages, giant cells and other inflammatory cells consequent to cholesterol deposition in tissue [1, 2]. They are generally found in the setting of types II or III hyperlipidemia (hypercholesterolemia and hypertriglyceridemia). However, they rarely occur in individuals without metabolic anomalies [1, 3].
Tendon xanthomas appear more frequently in hand extensors and Achilles tendons [1, 2, 4]. Achilles tendon xanthomas are more frequent in the third decade of life and are often bilateral, although they can occur unilaterally, as in this case.
Clinical manifestations depend on lesion size: smaller lesions are generally asymptomatic, while bigger lesions may present with swelling, pain and difficulties in walking [1].
The MRI features are tendon thickening and abnormal morphology and signal pattern: loss of normal ventral margin concavity to a convex morphology; heterogeneous signal on T1 and T2 with hypointense (normal tendon fibres) intercalated with hyperintense areas (inflammatory infiltrate), many times with a diffuse “stippled” or reticulated appearance [1, 2, 5]. These findings are indistinguishable from tendon partial tears [1, 2, 4]. Diagnosis of xanthoma should be considered in case of absence of previous trauma or when lesions are bilateral, even when there is no history of hyperlipidemia, as occurred in this case.
The majority of lesions regress after medical treatment with hypolipidemic drugs. Surgery is reserved for larger lesions, often associated with symptoms [1].
MRI can assess changes before the tendon enlarges or the xanthomas become clinically detectable. Early diagnosis allows institution of adequate medical treatment, preventing or retarding progression of disease, including cardiovascular complications [2, 4].
Unilateral Achilles tendon xanthoma.
Based on the provided MRI images, the following observations can be made:
Considering the imaging findings and clinical background of a 28-year-old male with no hyperlipidemia history, chronic dull pain, and progressive swelling in the Achilles tendon area, the following diagnoses are suggested:
Taking into account the patient’s age, absence of traumatic history, and the characteristic “punctate” or “mesh-like” mixed signals on MRI, along with chronic swelling and dull pain in the Achilles tendon, a unilateral Achilles tendon xanthoma is highly suspected, even without a confirmed history of hyperlipidemia. Rarely, tendon xanthomas may occur in patients with normal lipid profiles.
If uncertainty persists, comprehensive blood lipid testing and other metabolic evaluations may be considered. A biopsy might be warranted to exclude other uncommon lesions.
The goal of rehabilitation is to alleviate pain while maintaining or improving Achilles tendon function and lower limb muscle strength. Guidelines based on the FITT-VP principle (Frequency, Intensity, Time, Type, Volume, Progression) are as follows:
During rehabilitation, monitor pain and swelling closely, and proceed gradually to avoid excessive strain. For patients with potential lipid abnormalities or metabolic issues, risk factor control and regular follow-up of lipid profile and cardiovascular status may be necessary.
The above report is intended for reference only and does not substitute professional face-to-face assessment or a formal medical consultation. For further questions or a more detailed diagnosis and treatment plan, please seek in-person evaluation and follow the advice of a specialist.
Unilateral Achilles tendon xanthoma.
