Acute liver failure (ALF) is a life-threatening condition commonly caused by drug-induced hepatotoxicity or viral hepatitides. However, there are a number of rarer causes such as Haemophagocytic Lymphohistiocytosis (HLH). HLH is a syndrome of uncontrolled immune cell activation, triggered by infection or malignancy, which carries
a high mortality. Whilst mild to moderate liver injury is commonly seen with HLH, acute liver failure has rarely been reported in adults. We present a case of a 74 year old man with acute liver failure secondary to HLH triggered by undiagnosed large B-cell lymphoma. Initially treated for biliary sepsis, there was a delay in the diagnosis of HLH and despite initiating chemotherapy, he died soon after. This case highlights the importance of considering HLH as a rare cause of acute liver failure, as given the life-threatening potential of HLH, a prompt diagnosis may allow early initiation of chemotherapy for any chance of survival.