Abstract
Mucous cysts of the maxillary sinus are a pathological entity caused by dilatation and disturbance of ducts within the sinus mucosa resulting from damage or blockage of the ducts of seromucous nasal glands. There has been little histopathological and immunohistochemical research about the characteristics and onset mechanism of these cysts, until now. The present study was to investigate the mucous cysts of the maxillary sinus in order to understand their nature and genesis. Mucous cysts of the maxillary sinus were rare, occurring in seven cases(4.1%)among the 171 cases with cysts in the maxillary sinus. Four of the cases had cysts corresponding to primary cysts, and three cases corresponding to secondary cysts due to some treatments. Histologically, the extravasation type cysts of six cases showed a lot of mucoid material in connective tissue with mucinophage, lymphocyte, plasmacyte, and eosinophilic inflammatory cell infiltration and then mucous granuloma formation, and bleeding. In the retention type cyst of one case, the inner surface of the cyst was covered with ciliated columnar, cuboidal epithelium and sometimes apocrine metaplasia including mucoid material in it. Immunohistochemically, IgG and IgA positive plasmacytes were seen most often, and these cells were thought to contribute to the humoral immunity. There were also some IgEpositive cells(3 cases)only associated with mast cells, which had the relationship of type I allergy. Anti-GCDFP-15 antibody was observed not only in apocrine metaplasia cells, but also in existing dilated and hyperplastic ductal epithelial cells in the extravasation type. Anti-GCDFP-15 was thought to have a cross relationship to dilatation and hyperplasia of the cyst.
