Head and Neck ImagingInverted papilloma
uncommon epithelial
tumour of the nose and
paranasal sinuses. The name refers to the characteristic invagination of the proliferating epithelium beneath the surface. Inverted papillomas typically arise from the lateral nasal wall, in the region of the middle turbinate. At presentation, they often involve both the nasal cavity and the adjacent maxillary cavity; the ethmoids may also be involved, but extension to the frontal and sphenoid
sinus is not seen so often. A
polypoid mass is seen during clinical examination, sometimes resembling an
antrochoanal polyp. Recurrence after resection is fairly common. In 1015% of patients, an associated
squamous cell carcinoma head and neck is found in the resection specimen. Even in the absence of frank malignancy, an inverted papilloma may behave aggressively, with rapid recurrences and invasion of surrounding structures.
Apart from showing the location of the tumour mass at the junction of the nose and maxillary antrum, usually with a well defined bone defect at the maxillary ostium, CT may demonstrate the presence of intratumoral calcifications (Fig.1). Sometimes the bony walls adjacent to the tumour appear sclerotic. Some inverted papillomas are radiologically indistinguishable from an antrochoanal polyp. Because of the sclerosis of the sinus wall, it may also mimic chronic sinus infection. The MR characteristics of the soft tissue mass are nonspecific, not allowing differentiation from other tumour types.
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Coronal CT image, showing expansile mass lesion in the left nasal cavity and ethmoid cells, bulging into the maxillary ostium. The mass contains rough calcifications. The opacification of the left maxillary sinus corresponded at surgery to retro-obstructive inflammation; the tumour extended to the floor of the nasal cavity.
Airfluid level in right maxillary sinus: acute inflammation.
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Inverted papilloma, Fig.1 | |