HLH Diagnosis — RACP Adult Medicine MCQ

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HardHaematologyHLH DiagnosisRACP Adult Medicine

A 45-year-old man with inflammatory bowel disease on infliximab develops persistent high fevers and night sweats. CT shows hepatosplenomegaly and generalised lymphadenopathy. Bone marrow biopsy shows haemophagocytosis. His ferritin is 45,000 µg/L, triglycerides are elevated, and fibrinogen is low. What is the diagnosis?

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Correct answer: C — Haemophagocytic lymphohistiocytosis (HLH)

HLH is a hyperinflammatory syndrome characterised by uncontrolled activation of macrophages and T cells. The H-Score clinical criteria include: fever, organomegaly, cytopaenias, hyperferritinaemia (>500 µg/L; >10,000 highly specific), hypertriglyceridaemia, low fibrinogen, elevated soluble IL-2 receptor, and haemophagocytosis on biopsy. In adults, HLH is usually secondary to infections (EBV most common), malignancy (lymphoma), or autoimmune disease (macrophage activation syndrome – MAS). Anti-TNF therapy may contribute through immunosuppression allowing EBV reactivation. Treatment is the HLH-2004 protocol (etoposide, dexamethasone, ciclosporin) plus treatment of the underlying trigger.

Reference: eTG – 2025 – Haematology; Histiocyte Society – 2004 – HLH-2004 Protocol