ABSTRACT
Background: Haemophagocytic lymphohistiocytosis (HLH) is a rare and potentially life-threatening systemic hyperinflammatory disease, which can have several aetiologies. Clinical case: a 48-year-old woman affected by a transfusion-dependent β-thalassemia was hospitalized in our haematology unit presenting with intermittent fever, haepatosplenomegaly and pancytopenia, which developed a few days after the booster dose of anti-SARS-CoV-2 mRNA vaccine. The investigations performed during hospitalization led to a diagnosis of HLH and steroid therapy where IV dexam-ethasone was initiated and provided benefits. Conclusions: the severity of HLH mandates early treatment, but the management of patients with post-vaccine HLH is still challenging and requires further study. No cases of HLH in patients with thalassemia were previously described.