A 48-year-old female patient presented to the ENT outpatient department of Hospital das Clínicas, in Belo Horizonte, Brazil, with headache, nasal obstruction, non-purulent nasal discharge and right-sided facial pain. She had been previously treated with antibiotics without significant clinical improvement. She denied fever. She also reported having undergone a surgical removal of an odontogenic cyst ten years before, which was complicated by a right-sided oroantral fistula. Normal-sized nasal turbinates were observed on examination. A computed tomography of the paranasal sinuses was requested.

Question:
Based on the clinical scenario and image presented, the most likely diagnosis is: