What is the radiological finding when disease is limited to the infundibulum of the maxillary sinus ostium?

Isolated obstruction of the maxillary sinus is observed, often presenting as opacification or fluid levels on imaging. Key diagnostic features include unilateral sinus opacification with a patent nasal cavity. Clinically, this can lead to symptoms of sinusitis localized to the affected side. A common pitfall is mistaking this for chronic sinusitis affecting multiple sinuses, so careful evaluation of the infundibulum is crucial.