Haemophagocytic lymphohistiocytosis (HLH) in an adult following treatment with trimethoprim/sulfamethoxazole

Haemophagocytic lymphohistiocytosis (HLH) is an aggressive hyperinflammatory haematological condition often associated with malignancy, infection or rheumatological disorders. HLH has rarely been associated with medications, including antibiotics. We describe a case of a patient without significant medical history who presented with HLH following treatment with trimethoprim/sulfamethoxazole (TMP/SMX). Additionally, we will discuss the possible mechanism of medication-induced HLH as well as the successful use of dexamethasone as the sole treatment. Early diagnosis and treatment of this disease is critical and medication-induced HLH should be considered in cases without a clear aetiology. To our knowledge, this is the first case report of TMP/SMX-induced HLH that was successfully treated with steroid monotherapy and just the second case report of TMP/SMX-induced HLH.