Acute liver failure is the development of severe hepatic injury with deterioration of liver synthesis function and encephalopathy. Among all the variety of causes, neoplastic infiltration represents less than 0.5%. We present the case of a male patient with a past medical history of HTLV-1 infection, who reports symptoms of acute hepatitis, being diagnosed with Adult T-cell leukemia/lymphoma. Unfortunately, the patient had a rapid deterioration and passed away a few days after admission.