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Hemophagocytic lymphohistiocytosis — Clinical Guidelines

Overview

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome characterized by excessive immune activation, leading to multiorgan dysfunction 1 2 22.

Diagnosis

Clinical Criteria: Fever, splenomegaly, cytopenias, hypertriglyceridemia, hypofibrinogenemia, hemophagocytosis in bone marrow or other tissues 6 14.

Laboratory Tests: Elevated ferritin, soluble IL-2 receptor (sIL-2R), and inflammatory markers 6 33.

Genetic Testing: For suspected primary HLH, genetic testing for mutations in PRF1, UNC13D, STX11, and STXBP2 6 44.

Differentiation: Distinguish from sepsis and other inflammatory conditions using HLH-90 criteria or HLH-2004 guidelines 8 22.

Management

First-Line Treatments:

- Corticosteroids: High-dose glucocorticoids (e.g., dexamethasone) 23 38. - Immunosuppressive Agents: Intravenous immunoglobulin (IVIG) 23 38.

Adjunctive Therapies:

- Anakinra: Continuous intravenous anakinra for severe cases 18 23. - Chemotherapy: In secondary HLH, treat underlying malignancy 24 38. - Stem Cell Transplantation: Consider in refractory cases or primary HLH 38.

Special Populations

Pediatrics: Early recognition and prompt initiation of therapy are crucial; primary HLH often requires hematopoietic stem cell transplantation 6 14 38.

Elderly: HLH in older adults often complicates underlying diseases; treatment focuses on managing comorbidities and immune dysregulation 26 32.

Pregnancy: HLH can be triggered by infections like cytomegalovirus; management requires multidisciplinary care to balance maternal and fetal outcomes 41.

Comorbidities: Presence of underlying conditions like lymphoma or autoimmune diseases influences prognosis and treatment strategies 50 55.

Key Recommendations

Early Diagnosis and Aggressive Treatment: Initiate treatment promptly using corticosteroids and IVIG for suspected HLH to improve outcomes 10 23 (Evidence: Strong).

Consider Underlying Causes: Evaluate and treat underlying infections or malignancies in secondary HLH to enhance survival 24 38 (Evidence: Moderate).

Use of Anakinra in Severe Cases: Employ continuous intravenous anakinra for critically ill patients with severe HLH 18 23 (Evidence: Moderate).

Timely Specialty Consultation: Early subspecialty consultation can expedite diagnosis and management, potentially improving outcomes 13 (Evidence: Moderate).

Monitor Organ Dysfunction: Closely monitor for hepatobiliary dysfunction and disseminated intravascular coagulation (DIC) as they predict poor prognosis in pediatric HLH 30 (Evidence: Moderate).

References

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Hemophagocytic lymphohistiocytosis