A Paediatric Case of Sphenoid Sinusitis and Resultant Secondary Masticator Space Abscess Requiring Surgical Management.

Paediatric sphenoid sinusitis is rare and potentially life-threatening, with delayed diagnosis increasing the risk of intracranial complications. Masticator space abscesses are also uncommon, often arising from odontogenic infection. We describe the case of a healthy early adolescent male patient with sphenoid sinusitis complicated by a secondary masticator space abscess without odontogenic involvement, with early erosion of the lateral pterygoid plate posited as a possible route of infection spread. The patient presented to the emergency department with nonspecific right-sided facial pain, swelling, and transient facial weakness. Urgent magnetic resonance imaging (MRI) with contrast confirmed sphenoid sinusitis.  He had an initial joint admission under both Paediatric and Ear, Nose, and Throat (ENT) surgical teams. In the month following initial discharge, he re-presented twice with subsequent imaging revealing a right masticator space abscess, and thereafter, recurrence with early erosion of the right lateral pterygoid plate. This required sphenoidotomy and abscess drainage on both occasions, necessitating involvement of the Oral and Maxillofacial Surgery (OMFS) team. With extended targeted intravenous antibiotic therapy, a full recovery was made. There are no cases of sphenoid sinusitis leading to a secondary masticator space abscess without odontogenic involvement described in the available literature. The anatomical separation and typical routes of infection spread make this complication exceedingly rare. This case illustrates the importance of high clinical suspicion, advanced imaging, and prompt, coordinated multidisciplinary management.