Inpatient recognition and management of HLH

Hemophagocytic lymphohistiocytosis (HLH) is one of the life-threatening emergencies that a hematologist may be called upon to diagnose and manage. It is a hyperinflammatory process that develops in patients with genetic abnormalities, hematologic malignancies, chronic inflammatory states, or infections. The main clinical challenges are recognizing HLH, determining whether the immune response is aberrant or appropriate, and deciding upon therapy. Patients may present with fever, central nervous system symptoms, cytopenias, or elevated liver enzymes. Recognizing HLH is challenging because its features overlap with numerous systemic disorders, thus requiring a high level of suspicion and timely investigations to confirm the diagnosis and detect the underlying trigger. Once HLH is diagnosed, careful consideration of immunosuppressive therapy's potential benefit versus harm is necessary. Such therapy can sometimes be tailored to the underlying trigger. In the acute setting, the competing pressures of completing a thorough diagnostic process (including evaluation for the presence of lymphoma and infection) and the need for expedited treatment must be balanced. During the management of an HLH patient, continuous vigilance for the presence of as-yet unrecognized disease triggers, monitoring response, and identifying emerging complications is critical. This review will discuss the recognition and management of HLH in the inpatient setting.