Atypical Presentation of Undiagnosed Crouzon's Syndrome With Pansinusitis, Orbital Cellulitis, and Altered Mentation Successfully Managed With Functional Endoscopic Sinus Surgery: A Case Report.

BACKGROUND: Crouzon's syndrome is a rare autosomal dominant craniosynostosis disorder characterized by midfacial hypoplasia due to premature fusion of the coronal and sagittal sutures. Facial features are typical in the form of a hypoplastic maxilla, shallow orbits, and mandibular prognathism. The condition is usually diagnosed during infancy or early childhood because of characteristic craniofacial features. Delayed diagnosis during adolescence is uncommon, and severe infective complications as the initial presentation are exceedingly rare. CASE SUMMARY: A 14-year-old boy with no known craniofacial diagnosis presented to the emergency department with fever, headache, altered mentation, and left eye swelling. Examination revealed proptosis, chemosis, and purulent discharge from the left eye, along with midfacial hypoplasia and shallow orbits. Computed tomography and magnetic resonance imaging demonstrated extensive pansinusitis, orbital cellulitis, frontal bone osteomyelitis, and craniosynostosis-related craniofacial abnormalities. Initial empirical antimicrobial therapy was started and subsequently escalated following the isolation of carbapenem-resistant Pseudomonas aeruginosa. Owing to progressive disease, urgent functional endoscopic sinus surgery (FESS) was performed. The patient demonstrated rapid clinical improvement with resolution of orbital swelling and recovery of neurological status. Subsequent genetic testing confirmed an FGFR2 mutation, establishing the diagnosis of Crouzon syndrome. CONCLUSION: This case highlights a rare late presentation of previously undiagnosed Crouzon syndrome with life-threatening infective complications. Recognition of craniofacial dysmorphism in patients presenting with severe sinonasal infections is essential for timely diagnosis and multidisciplinary management. Culture-directed antimicrobial therapy combined with appropriately planned FESS can result in excellent clinical outcomes.