Immune checkpoint inhibitor-associated hemophagocytic lymphohistiocytosis in a patient with chronic lymphocytic leukemia

Haemophagocytic lymphohistiocytosis (HLH) is a rare complication of immune checkpoint inhibitor therapy. A 55-year-old male with stable chronic lymphocytic leukemia presented with fevers and symptomatic anaemia after nine cycles of nivolumab for metastatic melanoma. Investigations were consistent with autoimmune haemolytic anemia and corticosteroids were initiated. Thrombocytopenia and elevated liver enzymes without evidence of chronic lymphocytic leukaemia transformation was present. Ferritin was elevated, and thus HLH was considered and subsequently confirmed on a bone marrow biopsy. Corticosteroid monotherapy was continued, with resolution of fevers and improvement in cytopenias and liver enzymes. A six month corticosteroid tapering regimen was initiated, and he remains in HLH remission. This case highlights the importance of prompt recognition of immune checkpoint inhibitor-related HLH in patients with concurrent haematological malignancy. 

Plain language summary: A 55-year-old man had skin cancer and treatment was started. He also had a blood cancer around the same time that was not causing any problems. The skin cancer treatment started to cause problems many weeks later. His immune system started to react and become more active and so his liver started to suffer. The treatment for his skin cancer was stopped and steroids were started, which eventually improved his condition. These treatments for skin cancer can activate the immune system, but to this extent is not very common. It is important to know that it is possible and needs to be actioned early. Tweetable abstract: Haemophagocytic lymphohistiocytosis and autoimmune haemolytic anaemia due to immune checkpoint inhibitors in a patient with metastatic melanoma and concurrent chronic lymphocytic leukemia with response to tapering corticosteroid therapy.