Chronic liver disease related to 6-thioguanine in children with acute lymphoblastic leukaemia

Background/AimsThe United Kingdom (UK) acute lymphoblastic leukaemia (ALL) 97/99 clinical trial compared 6-mercaptopurine (6MP) with 6-thioguanine (6TG) as maintenance therapy for childhood ALL. Review of interim results has led to discontinuation of the 6TG arm.MethodsWe report six children with ALL, who presented with splenomegaly after a median (range) treatment duration of 12 (6–22) months. All these children were treated in the 6TG-arm.ResultsThe median (range) age at presentation was 6.6 (3.2–11.5) years. There were five boys. The presenting features were splenomegaly in all and hepatomegaly in four. AST was abnormal in one (80 IU/l, normal range 10–50). Abdominal sonography showed an altered texture of the liver parenchyma and confirmed splenomegaly.Microscopy showed findings within the spectrum of occlusive venopathy and nodular regenerative hyperplasia (NRH). After a median (range) follow-up of 23 (4–36) months splenomegaly and thrombocytopenia, suggestive of progressive portal hypertension, continue to worsen in all children.Conclusions6TG is associated with chronic hepatic toxicity and progressive portal hypertension on follow-up. Microscopy showed NRH in all patients with features in keeping with an intrahepatic occlusive venopathy and variable parenchymal atrophy and loss.