Sinonasal polyposis is usually characterized on CT as soft tissue density polypoid masses within the nasal cavity and paranasal sinuses. As they are not so prominent in this case, it is easy to identify and spot them. In severe cases, in general, the sinuses are completely obliterated and remodeling of sinonasal bones is common. This diagnosis was based on imaging aspects only. 

The only differential diagnosis to be considered is: sinonasal retention cysts , which usually spare the nasal cavity and are commonly asymptomatic.