A new concept of the pathogenesis of oral mucous cysts based on a study of 200 cases.

A new hypothesis regarding the pathogenesis of mucous cysts of the oral mucosa is proposed. Based upon a histological study of 188 mucous cysts without epithelial lining out of a total of 200 cysts it is claimed that some cysts may not develop in any of the hitherto described ways as intraductal "mucous retention cysts" or extraductal "mucous extravasation cysts" or from destruction of acini due to the pressure of mucous caused by duct obstruction. It is suggested that some of the cysts, that are found to have developed intraglandularly, are caused by traumatic destruction of a large amount of glandular acini ("parenchymal destruction cysts") and continuous secretion from the remaining acini. The mucus from the disintegrated cells forms a pool, which in time is surrounded by a connective tissue capsule that contains remnants of parenchyma from the affected lobule. This parenchyma degenerates, and eventually the cyst shows the same histological picture as the "mucous extravasation cyst". It is argued that the presence of a feeder duct does not necessarily indicate an extravasation cyst, but may be seen in the "parenchymal destruction cysts" as well. Of the 188 cysts examined 20 (11 per cent) were found to develop intraglandularly, and 36 (19 per cent) were considered probably to have developed intraglandularly.