A case of pembrolizumab-induced hemophagocytic lymphohistiocytosis successfully treated with pulse glucocorticoid therapy.

Abstract Treatments using immune checkpoint inhibitors such as pembrolizumab lead to immune mediated adverse effects including hemophagocytic lymphohistiocytosis (HLH). Herein, we present a case where HLH developed after pembrolizumab administration, which was treated using high dose prednisolone. He developed high-grade fever complicated with liver dysfunction and diarrhea 7 days after pembrolizumab administration. Although treatment with oral prednisolone alleviated the symptoms, other adverse effects arose owing to a tapered prednisolone dose. Hyperferritinemia suggested the diagnosis of HLH and met the criteria for HLH diagnosis. He was thus administered intravenous pulses of methylprednisolone followed by high-dose oral prednisolone, which resolved these symptoms.