Abstract
In this report, we describe a rare case of xanthine crystals found in the urine sediment of a 63-year-old man who was receiving CHOP therapy for adult T-cell leukemia with allopurinol and rasburicase treatments to prevent the onset of tumor lysis syndrome (TLS). On day 3, a reduction in urine output and deposits in the urine were recognized. A urinary examination was performed, and we found brownish yellow crystals that had a rough surface resembling phosphate crystals in the patient’s urine sediment. Also, we found that these crystals were soluble in potassium hydrate but not in acetic acid and hydrochloric acid. Later, the crystals were identified as xanthine by infrared spectrum analysis. Allopurinol treatment was stopped and forced diuresis was performed, and then the crystals disappeared. In this patient, although the levels of serum uric acid were maintained below the detection limit, xanthine crystals were found with the increased production of xanthine owing to the inhibition of xanthine oxidase. The patient was able to continue cancer treatment without developing TLS. This is the first report describing the morphological identification of xanthine crystals in urinary sediment.
