Hepatic sinusoidal obstruction syndrome after immune-checkpoint-inhibitor therapy: when the liver sends SOS

A woman in her 50s presented to the hospital with new-onset jaundice and ascites. Her medical history included a melanoma of the right shoulder, diagnosed 8 months before, for which she had received four cycles of ipilimumab and nivolumab. Due to the oncological history and previous immunotherapy, an immune-checkpoint-inhibitor (ICI)-induced hepatitis was suspected, and a high-dose corticosteroid treatment was initiated. However, as there was no improvement in the liver function tests, a percutaneous liver biopsy was performed for further diagnostic clarification. Histological analysis ultimately identified a hepatic sinusoidal obstruction syndrome (SOS) as the underlying cause of liver dysfunction and portal hypertension. ICI-related hepatic SOS represents an extremely rare adverse event related to immunotherapy that should be considered in all patients with treatment-refractory ICI-related hepatotoxicity and clinical signs of portal hypertension.