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A ranula is a type of mucocele found on the floor of the mouth. Ranulas present as a swelling of connective tissue consisting of collected mucin from a ruptured salivary gland duct, which is usually caused by local trauma.
The latin rana means frog, and a ranula is so named because its appearance is sometimes compared to a frog's underbelly.
Locations
The gland that most likely causes a ranula is the sublingual gland. Nonetheless, the submandibular gland and minor salivary glands may be involved.
Appearance
An oral ranula is a fluctuant swelling with a bluish translucent color that somewhat resembles the underbelly of a frog Rana. If it is deeper it does not have this bluish appearance. If it is large ( 2 or more cm.), it may hide the salivary gland and affect the location of the tongue. Most frequently it stems from the sublingual salivary gland, but also from the submandibular gland.
Though normally above the mylohyoid muscle, if a ranula is found deeper in the floor of the mouth, it can appear to have a normal color. A ranula below the mylohyoid muscle is referred to as a "plunging or cervical ranula", and produces swelling of the neck with or without swelling in the floor of the mouth.
Ranulas measure several centimeters in diameter and are usually larger than mucoceles. As a result, when ranulas are present the tongue may be elevated. As with mucoceles, ranulas may be subject to recurrent swelling with occasional rupturing of its contents. When pressed, they may not blanch.
Symptoms
Ranulas are usually asymptomatic, although they may change gradually in size, shrinking and swelling, making most ranulas hard to detect. The overlying skin is usually intact. The mass is not fixed and is also not tender. The mass is not connected to the thyroid gland or lymph nodes. The mass may not be well defined. If it gets large enough it may interfere with swallowing, and cervical ranulas may even interfere with breathing. Some pain may be connected with very large ranulas.
Histology
Microscopically, ranulas are cystic saliva filled distensions of salivary gland ducts on the floor of the mouth alongside the tongue, and are lined by epithelium. A salivary mucocele, in contrast is not lined by epithelium.
Treatment
excision of both mandibular and major sublingual glands in a dog
Treatment of ranulas could involve either a procedure known as "marsupialization" or more often excision of both the gland and lesion. Ranulas are likely to reoccur if the sublingual gland or other gland causing them is not also removed with the lesion. There is little morbidity or mortality connected with treatment.
References
- Kahn, Michael A. Basic Oral and Maxillofacial Pathology. Volume 1. 2001.
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