Mucocele

A breach in the duct of a minor salivary gland allows for the extravasation of saliva creating a mucocele. If the mucous escape is near or within the intraepithelial portion of the duct, the lesion appears as a small translucent vesicle, the superficial mucocele. Multiple superficial mucoceles should not confused with vesiculobullous diseases. More commonly, the breach occurs in the deeper portions of the duct resulting in a more deeply seated, broad-based mucosal swelling that may be blue-tinged. Those that occur in the floor of the mouth may grow to several centimeters in size, fill the floor of the mouth, and elevate the tongue. The resemblance to the abdomen of a frog (Rana frog) gives rise to the name, "ranula." Large ranulas may separate the fibers of the mylohyoid muscle and spread into the neck, referred to as plunging ranula. The lower lip is the most common location for mucoceles but any mucosa in which there are minor glands is a potential target. Sometimes forgotten are the glands of Blandin, located in the midline of the ventral tongue, the only site on the tongue where mucoceles are regularly encountered. Von Ebner's glands on the posterior dorsal tongue seem peculiarly immune. The typical presentation is a painless swelling of several weeks duration that has waxed and waned in size, a finding explained by cyclical episodes of secretion-resorption that alternately fill and empty the mucous lake. Microscopic examination reveals an intramucosal lake of extrava-sated salivary secretion walled off by a margin of cellular fibrous connective tissue from which is shed foamy histiocytes. The accumulation of histiocytes may be so dense that the lesion resembles a clear cell salivary tumor. Late lesions may be virtually obliterated by the ingrowth of granulation tissue. Mucoceles do not voluntary resolve and require surgical excision including the gland that feeds them. It is surprising that the procedure does not create new mucoceles. Large lesions in the floor of the mouth respond to marsupialization.

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