Xanthine urolithiasis.

Xanthine calculi are uncommonly encountered stones. When they occur, they typically do so in association with inborn metabolic disorders such as hereditary xanthinuria or Lesch-Nyhan syndrome. They may also occur in association with states of profound hyperuricemia such as myeloproliferative disease after treatment with allopurinol. If the underlying disorder is not addressed, a high risk of stone recurrence exists. Therefore, to raise clinical awareness, we reviewed and report our experience in the treatment of patients with these stones, discussing the underlying pathophysiology and approach to treatment.