[A case of Achilles tendon rupture in a patient of refractory Reiter's syndrome].

We herein report a case of spontaneous rupture of Achilles tendon in a 51-year-old man with refractory Reiter's syndrome. On the diagnosis in November, 2006, physical examinations and MR images showed a remarkable inflammation at the calcaneal insertion area of Achilles tendon. He required aggressive treatments with nonsteroidal anti-inflammatory drug (NSAID), oral prednisolone 30 mg daily and methotrexate (8 mg weekly) to control the disease. Two months later, the Achilles tendon ruptured at its insertion point. This ruptured lesion of Achilles tendon was an unusual site compared to previous reports. Histological findings in the ruptured lesion of Achilles tendon revealed the existence of granulomatous lesion consisted of severe infiltration of fibroblasts and vessels proliferation beside tendon. These findings suggest a prolonged inflammation. Although it is widely accepted that Reiter's syndrome is associated with enthesis, especially at the attachment of Achilles tendon to calcaneum, there have been only two reports of Achilles tendon rupture associated with Reiter's syndrome. The possible cause of the Achilles tendon rupture in this patient might be due to the weakened strength of the Achilles tendon by the prolonged and severe enthesis of Achilles tendon near the insertion lesion.