Haemophagocytic Lymphohistiocytosis Triggered by Cytomegalovirus Reactivation in An Immunosuppressed Patient with Pauci-Immune Glomerulonephritis.

We report on a 67-year-old male patient admitted to the Internal Medicine department for fever, joint pain and exertional dyspnoea. Two months before his admission, the patient had been diagnosed with pauci-immune necrotising glomerulonephritis, for which he had been treated with rituximab and corticosteroids. Upon admission the patient was stable, but within a few hours he became unstable as liver failure and acute cytopaenia occurred. Blood investigations revealed cytopaenia, altered coagulation tests, high ferritin, triglycerides, lactate dehydrogenase and C-reactive protein levels, and severe cytocholestasis. A liver echography was normal. The patient had been transferred to the intensive care unit to receive supportive support when the cytomegalovirus polymerase chain reaction (CMV-PCR) test came back positive. The diagnosis of haemophagocytic lymphohistiocytosis associated with a CMV infection and/or reactivation in an immunosuppressed patient was made. Specific treatment was administrated, along with symptomatic treatment. The patient clinically improved during hospitalisation with complete resolution of symptoms.

Learning points: Haemophagocytic lymphohistiocytosis (HLH) is a rare disease yet important to diagnose, as it is quickly life-threatening.The diverse symptoms of HLH can make diagnosis tricky, with many potential causes. As clinical presentation is not very specific, it is often mistaken for infection with severe sepsis and its diagnosis is often delayed.Limited understanding of this condition could lead to worse outcomes for patients. Recognising it early is crucial for starting the right treatment and enhancing both the well-being and survival chances of those affected by this complex disorder.In practice, HLH must be suspected when bi/pancytopaenia occurs in a patient presenting a high fever of unknown cause, especially when they have a history of immunosuppression. Managing it often requires a range of approaches, such as intensive care, immune system suppression, specialised medications or even stem cell transplants.