Optimum imaging for inverted papilloma

Inverted papilloma is the most common benign tumour of the nose and paranas al sinuses, and usually arises in the lateral wall of the nasal cavity and the middle meatus. The diagnosis is suggested on computed tomography (CT) w hen there is a mass continuous from the middle meatus into the adjacent max illary antrum, through an expanded maxillary ostium. The mass may contain a reas of high density or calcification, and there may be sclerosis of the wa ll of the affected sinus. The main advantage of magnetic resonance imaging (MRI) is in defining the extent of the tumour, and in differentiating it fr om adjacent inflammatory tissue, but there are no certain signal intensity or enhancement characteristics to help differentiate inverted papilloma fro m sinus malignancy. In the differential diagnosis, antro-choanal polyp, mal ignant sinus tumours and chronic rhinosinusitis and fungal disease need to be excluded. The combination of bone deformity and sclerosis with the typic al antro-meatal mass suggests a slow-growing tumour such as inverted papill oma.