Salivary duct cyst: its frequency in a certain Japanese population group (Tohoku districts), with special reference to adenomatous proliferation of the epithelial lining.

It is reported in the European and American literature that salivary duct cysts constitute about 10% of all cysts of the salivary glands, although they appear to be rare in Japan. Between 1975 and 1999, only 3 (0.5%) of 586 salivary gland cysts were diagnosed as salivary duct cysts at the Division of Clinical Pathology, Iwate Medical University Hospital. Histologically, two cases appeared as a unilocular lesion lined by double- and multi-layered epithelium. The other case showed marked, intraluminar and intramural adenomatous proliferation of the epithelial lining, suggesting that the lesion was a benign tumor. A review of the literature yielded only two cases of tumors arising in pre-existing salivary duct cysts.