Haemophagocytic lymphohistiocytosis
| "sepsis-like syndrome" - yet another aseptic cause of distributive shock | |
|---|---|
| Etiology | Primary = genetic defects in inflammasome regulation/cytolytic function of cytotoxic T cells. Secondary HLH = triggered by viral (EBV, CMV...), malignancy, intracellular infection e.g. Rickettsia, organ transplantation... |
| Epidemiology | |
| Clinical presentation | Fever, hepatosplenomegaly, bleeding Non-specific - lymphadenopathy, organ failure... Diagnostic: ↑ ferritin, ↑ triglycerides, ↓ lymphocytes H score can be used to decide but it's Ddx: |
| Pathogenesis | - Antigen presenting cells activate T cells → cytotoxic effector T cells present antigen to lymphocytes - activated T cells would usually inhibit APCs - which doesn't happen in HLH - Interferon gamma activates macrophages → IL-6, TNF-alpha, plasminogen activators, directly cause haemophagocytosis |
| Diagnostic investigations | Ferritin, triglycerides, FBC LDH |
| Management | Complications: - Etoposide, dexamethasone - IVIG? Anakinra (inhibits effects of IL-1)? Tocilizumab (block IL-6)? - Any specific antimicrobial treatment (e.g. for TB, Rickettsia...) |
sources/links
https://derangedphysiology.com/main/required-reading/haematology-and-oncology/Chapter-212/haemophagocytic-lymphohistiocytosis
https://onlinelibrary.wiley.com/doi/abs/10.1111/imr.13298
https://pmc.ncbi.nlm.nih.gov/articles/PMC5867532/
https://ashpublications.org/blood/article/133/23/2465/273833/Recommendations-for-the-management-of