Information from xanthine crystals appearing in the urine of a patient with hematologic malignancy

Abstract

Xanthine crystals that appear during chemotherapy of tumors have been reported to be rare, and they are characterized as being plate-like. We encountered a case in which we suspected the appearance of xanthine crystals, but instead of seeing plate-like crystals, only granular agglomerates were seen, followed by the appearance of typical xanthine crystals. The patient was a female in her 30s. After remission of Ph-negative B-ALL, she underwent nonrelated peripheral blood stem cell transplantation. After hospitalization, chemotherapy was started. Febuxostat was administered to prevent tumor lysis syndrome (TLS) due to the marked disintegration of tumor cells. On day 7 of admission, urine sediment showed granular agglomerates, which were not identified, followed by the appearance of xanthine crystals on day 38, with plate-like and granular morphological characteristics. Both were soluble in potassium hydroxide and insoluble on heating and in hydrochloric acid and normal saline. On day 7 of hospitalization, the urine had a neutral pH of 7.0 and the urine volume was maintained, suggesting that the xanthine crystals were in the process of forming typical platelets. The urinary sediment suggests that crystals may have been involved in renal impairment. Therefore, the detection of xanthine crystals is highly significant, and it is important to understand that xanthine crystals may not show the typical platelet-like shape as in this case.