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Hemophagocytic Lymphohistiocytosis
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Hemophagocytic Lymphohistiocytosis
Epidemiology
Rare
Pathophysiology
Impaired
Natural Killer Cell
activity triggers over-activation of
Macrophage
s and cytotoxic T Cells (CD8 T Cells)
Immune System
overactivation with histiocyte,
T-Cell
and
Macrophage
accumulation in the skin, liver and
Spleen
Results in
Phagocytosis
of
Red Blood Cell
s,
White Blood Cell
s and
Platelet
s
Also results in increased
Cytokine
release with a severe inflammatory response
Causes
Primary (Hereditary)
Diagnosed in infancy
Secondary (Significant physiologic stressors)
Infection
Immunodeficiency
Autoimmune Condition
s
Malignancy
Differential Diagnosis
Sepsis
Acute Hepatic Failure
Disseminated Intravascular Coagulation
Influenza
-like illness (e.g.
Covid19
)
Toxin Ingestion
Antiphospholipid Syndrome
Drug Reaction with Eosinophilia and Systemic Symptoms
(
DRESS Syndrome
)
Findings
Fever
(>90%)
Splenomegaly
(>80%)
Hepatomegaly
(>60%)
Respiratory dysfunction (>30%)
CNS dysfunction (>30%)
Labs
Labs should also address differential diagnosis (e.g.
Sepsis
)
Complete Blood Count
Pancytopenia
Comprehensive Metabolic Panel
Abnormal
Liver Function Test
s
Hypoalbuminemia
Serum Ferritin
Levels are frequently >2000 mcg/L
Coagulation Studies (e.g. PTT, INR)
Coagulopathy
Fibrinogen
decreased
D-Dimer
increased
Other Studies
Serum Triglyceride
s increased
Management
Patients typically present with toxic appearance
ABC Management
Fluid
Resuscitation
Antibiotics are typically started (due to risk of underlying infectious cause)
Consult Hematology and
Intensive Care
Medicine
Discuss evaluation and management
Antiiflammatory agents are typically used
Corticosteroid
s
Biologic Agent
s (e.g.
Anakinra
,
Ruxolitinib
,
Etoposide
)
Prognosis
Mortality 20 to 80% (increased with delayed diagnosis)
Resources
Konkol S, Rai M (2022)
Lymph
ohistiocytosis, StatPearls, Treasure Island, FL,
https://www.ncbi.nlm.nih.gov/books/NBK557776/
References
Long and Lentz in Swadron (2022) EM: Rap 22(8): 11-2
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