Abstract
Genuine cysts of the paranasal sinus are commonly found in the frontal or ethmoidal sinus, but rarely in the maxillary sinus. They are apparently caused by the obstruction of the outlet of the sinus in the nose.
Non-odontogenic cystic lesions of the maxillary sinus are highly suggestive of a malignant growth when there is evidence of bony destruction and enlargement of the maxillary sinus cavity on radiological examination. For differential diagnosis, computed tomography (CT) can be useful in addition to the conventional radiological examination.
Two cases of non-odontogenic cyst of the maxillary sinus were examined by conventional radiology and CT scan. The first patient with a painless swelling in the left cheek was differentiated from a malignant tumor by the difference of density between the cyst wall and cyst fluids on CT scan. The second case complaining of left nasal obstruction was suspected of having malignancy in the left maxillary sinus on CT scan, because the cyst contents were filled with fibrin mass. The correct diagnosis was obtained from surgery and histopathological examination.
In the cystic lesions of the paranasal sinus, CT scan is not very reliable for the detection of differences of density according to the nature of the cyst fluids.
