Abstract Introduction Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening syndrome of immune overactivation, characterized by fever, cytopenias, hyperferritinemia, organ dysfunction, and high mortality if untreated. HLH can be triggered by malignancy, infection, or immune dysregulation. HLH precipitated by minor surgical procedures and concurrent infections are rarely reported in literature. HLH can be delayed in diagnosis due to its rarity, variable clinical presentation and overlapping with other conditions like sepsis. Case Presentation 67-year-old male with history of chronic lymphocytic leukemia (CLL), myelodysplastic/myeloproliferative neoplasm (MDS/MPN) overlap, and prior splenectomy who presented with severe right knee pain two days after elective arthroscopic meniscectomy. He was afebrile with night sweats. Labs showed leukocytosis (WBC 229K/µL), elevated lactate (2.2 mmol/L), and normal CRP. Imaging revealed a knee effusion. He was admitted for pain management and empiric antibiotics. Within 72 hours, he developed respiratory failure, encephalopathy, jaundice, worsening cytopenias (Hb 6.8 g/dL, Plt 21K), coagulopathy, renal failure, and lactate 9 mmol/L. Ferritin was 1650 ng/mL; triglycerides and IL-2 receptor were markedly elevated (27,062.3 pg/mL; normal 858.2). Viral panel was positive for rhinovirus and influenza A. Blood cultures remained negative. HLH was suspected, Jakafi and hydroxyurea were held, and dexamethasone 10 mg/m²/day was initiated. Despite aggressive medical care, he deteriorated and was transitioned to hospice. Discussion This case highlights the potential for routine surgical procedures to trigger HLH in immunocompromised hosts. Viral infection, recent surgery, and underlying malignancy likely acted synergistically. Clinicians should maintain a high index of suspicion for HLH in postsurgical patients with rapid clinical decline, even without initial fever. H score can be used to estimate HLH risk, based on labs, fever, and cytopenias. Early intervention remains essential, though prognosis in malignancy-associated HLH is poor. This abstract is funded by: None
Guliani et al. (Fri,) studied this question.