Work

Pentasystem embolism associated with transient antiphospholipid antibodies in severe M. pneumoniae pneumonia: a “Dual-Hit” case report and systematic review

Year: 2026

Type: review

Abstract: Background: pneumonia (SMPP) in children, yet its clinical spectrum and immunothrombotic mechanisms remain poorly defined. The "dual-hit" hypothesis-synergy between infection-induced inflammation and transient antiphospholipid antibodies (aPLs)-lacks integrated clinical validation. Methods: We report a case of extensive multi-system thrombosis in a 6-year-old boy with SMPP. A systematic review of literature (January 2020-December 2025) identified 19 studies comprising 199 pediatric cases. Results: In the index case, thrombosis coincided with hyperinflammation and transient aPLs, which seroconverted to negative upon recovery. Pooled analysis showed multi-system involvement in 27.1% of cases (54/199). Among tested patients (n = 65; 32.7% of the cohort), aPL positivity was 69.2% (45/65). Most patients achieved favorable outcomes with anticoagulation and immunomodulation. Conclusion: This study is consistent with the "dual-hit" model in SMPP, where systemic inflammation may prime the endothelium and transient aPL positivity coincides with an extensive thrombotic burden. The high prevalence of multi-system involvement supports low-threshold vascular imaging and aPLs screening, along with biomarker-guided management. Transient aPLs should be interpreted as a potential risk-amplifying biomarker rather than a proven causal driver of thrombosis.

Source: Frontiers in Immunology

DOI: 10.3389/fimmu.2026.1845246