{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T10:09:19Z","timestamp":1788775759745,"version":"build-2803163510"},"reference-count":14,"publisher":"SMC Media","issue":"9","license":[{"start":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T00:00:00Z","timestamp":1787529600000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome driven by dysregulated activation of cytotoxic T lymphocytes and macrophages. While infections and malignancies represent the most frequently identified triggers, HLH precipitated by arthropod envenomation is exceptionally rare, with prior reports confined predominantly to paediatric populations. Case description: A 65-year-old male with multiple comorbidities developed progressive fever, cytopenias, extreme hyperferritinaemia (&gt;8,000 ng\/ml), and multiorgan dysfunction following a suspected spider bite to the inner left thigh. Evaluation revealed markedly elevated soluble interleukin-2 receptor (sCD25 &gt;4,000 pg\/ml) and CXCL9 (35,623 pg\/ml; 55-fold above the upper limit of normal), along with reduced natural killer (NK) cell counts. Bone marrow biopsy confirmed haemophagocytosis. The patient fulfilled 6 of 8 HLH-2004 diagnostic criteria, with an HScore of approximately 197, corresponding to a &gt;90-95% probability of HLH. Treatment with high-dose corticosteroids, ruxolitinib, and anakinra resulted in rapid suppression of inflammatory markers. The course was complicated by acute kidney injury requiring temporary haemodialysis. By early 2026, the patient achieved normalization of all laboratory parameters and returned to near-baseline functional status. Conclusion: This case illustrates an exceptionally rare adult presentation of envenomation-associated secondary HLH. Clinicians should consider HLH in patients with persistent fever, cytopenias, and extreme hyperferritinaemia following arthropod exposure. Early immunomodulatory therapy, including cytokine-directed agents such as ruxolitinib and anakinra, may avert irreversible organ damage in the absence of cytotoxic etoposide-based therapy.<\/jats:p>","DOI":"10.12890\/2026_007013","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T10:30:51Z","timestamp":1787567451000},"source":"Crossref","is-referenced-by-count":0,"title":["Envenomation-induced hemophagocytic lymphohistiocytosis (HLH): first reported adult case following a spider bite"],"prefix":"10.12890","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-7064-1338","authenticated-orcid":false,"given":"Justin","family":"Baik","sequence":"first","affiliation":[{"name":"Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Faizan","family":"Khajar","sequence":"first","affiliation":[{"name":"Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Neil","family":"Hughes","sequence":"first","affiliation":[{"name":"Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Muhammad","family":"Usman","sequence":"first","affiliation":[{"name":"Bronson Methodist Hospital Hematology, Medical Oncology, Kalamazoo, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"10397","published-online":{"date-parts":[[2026,8,24]]},"reference":[{"key":"10.12890\/2026_007013_ref1","doi-asserted-by":"crossref","unstructured":"Ramos-Casals M, Brito-Zer\u00f3n P, L\u00f3pez-Guillermo A, Khamashta MA, Bosch X. 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A rare cause of secondary hemophagocytic lymphohistiocytosis: systemic loxoscelism. Turk J Pediatr 2020;62:641\u2013646. doi: 10.24953\/turkjped.2020.04.014","DOI":"10.24953\/turkjped.2020.04.014"},{"key":"10.12890\/2026_007013_ref8","doi-asserted-by":"crossref","unstructured":"Nittner-Marszalska M, Kosinska M, Suchnicki K, Rzeszutko M. Hemophagocytic Lymphohistiocytosis (HLH) Triggered by Wasp Venom Immunotherapy Is Rare but Noteworthy. J Investig Allergol Clin Immunol 2019;29:49\u201351. doi: 10.18176\/jiaci.0322","DOI":"10.18176\/jiaci.0322"},{"key":"10.12890\/2026_007013_ref9","doi-asserted-by":"crossref","unstructured":"Isbister GK, Fan HW. Spider bite. The Lancet 2011;378:2039\u201320 47. doi:10.1016\/S0140-6736(10)62230-1","DOI":"10.1016\/S0140-6736(10)62230-1"},{"key":"10.12890\/2026_007013_ref10","doi-asserted-by":"crossref","unstructured":"Crayne CB, Albeituni S, Nichols KE, Cron RQ. The Immunology of Macrophage Activation Syndrome. 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