Mucocele: Retention and extravasation types.

The most common non-neoplastic lesion of salivary gland tissue is the mucocele (also called sialocele and ptyalocele). A mucocele is defined as the pooling of mucin in a cystic cavity. Two types of mucoceles are recognized: (1) the retention type, in which the mucin pooling is confined within a dilated excretory duct or cyst, and (2) the extravasation type, in which mucin is spilled into the connective tissues from a ruptured or traumatized salivary gland duct.