Cureus. 2026 Sep 22;18(9):e116712. doi: 10.7759/cureus.116712. eCollection 2026 Sep.
ABSTRACT
Noonan syndrome is a genetically heterogeneous RASopathy associated with congenital cardiovascular abnormalities and a broad spectrum of hemostatic abnormalities. We report the case of an adult man with congenital pulmonary valve disease, previous radiofrequency ablation for Wolff-Parkinson-White syndrome, hepatosplenomegaly, and a clinical suspicion of Noonan syndrome who underwent repair of a previously unrecognized large left-sided diaphragmatic rupture. The defect contained the left colonic flexure, left kidney and adrenal gland, and parts of the stomach and spleen, and was repaired with primary closure and mesh reinforcement. A substantial postoperative left hemothorax developed and required thoracic drainage, followed by persistent and recurrent pleural collections. Subsequent thoracoscopy demonstrated marked inflammatory thickening of the parietal pleura, and pleurectomy was performed for chronic pleuritis. Hematological evaluation demonstrated mildly reduced factor XIII antigen levels on repeat testing, while factor XIII activity remained preserved. Molecular genetic testing subsequently identified a heterozygous pathogenic RIT1 variant, confirming Noonan syndrome. The available findings do not establish the reduced factor XIII antigen as the cause of the postoperative hemothorax. This case highlights the heterogeneous hemostatic phenotype of Noonan syndrome and the importance of comprehensive perioperative bleeding assessment, including targeted evaluation when clinically significant bleeding occurs.
PMID:42923906 | PMC:PMC13688289 | DOI:10.7759/cureus.116712