HLH in adults

Abstract

Hemophagocytic lymphohistiocytosis (HLH) in adolescent and adult patients (aHLH) is getting increasing attention due to an assumed rising incidence, a better pathophysiologic understanding, and a growing arsenal of therapeutic ammunition. For many years HLH used to be a domain of pediatrics and was almost totally neglected in adults. Nowadays, with raising awareness (although it is still severely underdiagnosed), more and more physicians face the challenges of diagnosis and treatment of aHLH. The aim of this chapter is to provide information on HLH, specifically in adults. The spectrum of underlying conditions, triggering factors, and genetic predisposition differs in age groups with enrichment of familial disease in children and enrichment of malignant disorders as underlying condition and/or trigger in adults. These differences plus differential tolerance of drugs due to age and comorbidity guide the recommended aHLH treatment approach. Simply copying the pediatric recommendations to adults may have deleterious consequences. Treatment of HLH requires individual tailoring of anti-inflammatory and immunosuppressive treatment components combined with disease-specific treatment such as chemotherapy in malignancy or antimicrobial drugs in infection-triggered HLH. The clinical overlap to sepsis with high risk of missed diagnosis on intensive care units will also be discussed.