Imaging diagnosis of paranasal sinus mucocele in a Yorkshire Terrier dog

An 8-year-old, neutered male Yorkshire Terrier dog presented with left ventromedial canthus swelling over a one-month period, refractory to pharmacological therapy. There was no history of trauma. On ultrasonography, the lesion had cystic character filled anechoic fluid and hyperechoic sedimenting debris. The computed tomography (CT) CT-dacryocystography showed protruding from lacrimal sac fossa occupying defect in orbital plate an ethmoidal ectoturbinate surrounded by bony structure intact nasolacrimal system. underwent surgical resection cyst its content aspirated. Ethmoid mucocele diagnosed based on CT, cytologic examination, bacterial culture histopathologic findings. This case describes imaging characteristics ethmoid highlights importance CT dogs that poor response medical treatment.