Clinicopathologic study of the postoperative maxillary cyst.

Sixty cases of the postoperative maxillary cyst were studied clinicopathologically. The cysts accounted for 19.5% of all oral cystic lesions. Most of the patients were in their 20s and 30s at the time of diagnosis, and the postoperative duration was between 10 and 49 years. Radiographically, most cases revealed a unilocular cystic lesion. In two thirds of the cases, the lesion occupied more than half the volume of the maxillary sinus while the remaining one third of the cases revealed more limited lesions of the sinus. Histopathologically, cuboidal, squamous, and mixed epithelial cyst linings were observed, although the basic epithelial lining was the ciliated columnar type. Epithelial dysplasia was found in two cases. The cysts near the nasal cavity may originate from regenerated nasal mucosa, and the cysts that are located at a distance from the nasal cavity may be lined with epithelium derived from residual mucosa of the sinus entrapped during surgery to relieve sinusitis.