Head and Neck ImagingSinonasal cavities, polyposis
the presence of multiple nasal polyps is called polyposis. Histologically these polyps consist of pronounced stromal oedema, covered by respiratory epithelium. The pathogenesis of these polyps is not well known. They commonly originate from the ethmoid cells, and grow downwards into the nasal cavity. Usually both sides are more or less symmetrically affected. They may entirely fill the nasal cavity and prolapse into the
paranasal sinuses and/or nasopharynx. The clinical history is long-standing nasal
obstruction, recurrent sinusitis and headache.
CT typically shows bilateral convexily bordered nasoethmoidal soft tissue masses, causing demineralization of the bony ethmoid septa, upper and middle turbinate, and sometimes also widening of the ethmoidal complex (with bulging of the lamina papyracea) and widening of the ethmoid infundibulum (Fig.1) (Fig.2). Often many or all of the paranasal sinuses are opacified, due to sinusal extension of the polyps or retro-obstructive inflammatory changes.
Usually the diagnosis is straightforward by combining the clinical history, endoscopical aspect and radiographic findings. However, in rare instances a malignant tumour may mimic the radiological appearance of polyposis (Fig.3). A biopsy should be obtained in these patients to exclude the possibility of a neoplasm.
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Coronal CT-image. Complete opacification of the nasal cavities, ethmoid cells and maxillary sinuses in a patient with pronounced polyposis. Note demineralization of bony septa in ethmoid and nose.
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Sinonasal cavities, polyposis, Fig.1 | | Sinonasal cavities, polyposis, Fig.2 | | Sinonasal cavities, polyposis, Fig.3 |