What Is Xanthomas of the Achilles Tendon?
Xanthoma of the Achilles tendon is a rather rare, interesting orthopaedic condition that has important ramifications in internal medicine and dermatology because the lesion is associated with a specific disturbance of lipid metabolism.
Small lumps in the Achilles tendon are sometimes caused by high cholesterol levels, resulting in cholesterol deposits in the tendon itself. Aside from treating cholesterol itself, treatment for Xanthomas involves taking a biopsy of the lesion but leaving the nodules intact.
A xanthoma of a tendon infiltrates the tendon, but may also involve adjacent ligament, fascia, or periosteum. There is a predilection for the extensor tendons at the metacarpophalangeal joints of the fingers, but the Achilles tendons and patellar tendons may also be involved. Less commonly, the lesion may affect the tendon of the triceps or the extensor tendons of the toes. The plantar fascia is occasionally infiltrated. Ninety per cent of patients with tendon xanthomas will have involvement of the extensor tendons of the hands, and about half will have involvement of the Achilles tendon. The lesions only develop in patients with the hereditary form of hypercholesterolemia. The number and size of lesions correlate to some degree with the cholesterol level and the age of the individual.
Occasionally the lesions are confused with fibrous xanthomas of synovium. The fibrous xanthomas are solitary lesions found near or adherent to the synovial sheaths of their origin, but do not infiltrate tendons. They are not symmetrical and are not found near large tendons such as the Achilles, patellar, or triceps tendons, and they are not familial. Fibrous xanthomas are not associated with elevated serum cholesterol levels.