Imaging Studies
In general, imaging studies are not indicated in the evaluation of mucoceles and simple oral ranulas. Radiographic evaluation, in particular cross-sectional occlusal and panoramic films, are a consideration if sialoliths are a suspected contributing factor in the formation of oral and cervical ranulas.
Advanced imaging of the head and neck and mediastinum by CT scanning or MRI to define the extent of a cervical ranula and to eliminate other disease processes is prudent prior to surgical intervention. [28, 29]
Ultrasonography has also been used to evaluate the lesions, especially oral ranulas. [30, 29]
Procedures
If a vascular lesion cannot be excluded from the differential diagnosis, then aspiration of the lesion is prudent for evaluation of the fluid contents. Large mucoceles may be best treated by marsupialization because of the risk of traumatizing the labial branch of the mental nerve. Dissection of the lesion along with the adjacent salivary glands is indicated for moderate-sized lesions. The micromarsupialization technique and laser removal are additional treatment approaches. [31, 32, 33, 34] Liquid nitrogen cryotherapy has been used to manage mucoceles as an alternative to surgery. [35, 36, 37] Superficial mucoceles may require biopsy, in addition to direct immunofluorescence studies for immunoglobulins and complement, if a mucocutaneous disease is suspected in the differential diagnosis. Laser vaporization may be useful when multiple lesions are present and a diagnosis has been established. [38]
Usually, the sublingual gland is the origin of the ranula; however, occasionally, the submandibular gland may be affected also and only rarely is the source. Decompression of the oral ranula or the oral portion of a cervical ranula may be indicated. Some authors advocate marsupialization with packing of the pseudocyst with gauze. This technique allows removal of a smaller amount of tissue with better-defined interfaces and less likelihood of injury to the nerve and the Wharton duct. Surgical management of plunging ranula usually involves surgical removal of the sublingual gland with cervical incision and drainage. [29]
Mucus retention cysts require excisional biopsy. If the retention cyst is overlying the Wharton or Stensen duct, the cyst is unroofed, a lacrimal probe is inserted into the duct, and sialodochoplasty is performed.
Histologic Findings
The mucocele and the oral ranula have a well-delineated cavity that contains free mucinous material; this material is characteristic of these entities. The cavity wall lacks an epithelial lining and is considered a pseudocyst. The pseudocyst wall is composed of granulation tissue with fibroblasts, proliferating small-caliber vessels, and a mixed acute and chronic inflammatory reaction. Muciphages are usually present in the fibroconnective wall of the pseudocyst. The muciphage cells may be demonstrated by using mucicarmine staining. [39]
The cyst wall also has free mucin in the connective tissue stroma. The adjacent salivary gland tissue possesses dilated ducts, fibrosis, acinar atrophy, and chronic inflammation. Occasionally, a ruptured salivary duct that is feeding into the area may be identified. The mucosal surface may be atrophic with focal ulceration, or it may show epithelial hyperplasia with hyperkeratosis. Special stains, mucicarmine and Alcian blue, are useful in identifying mucin that is free in the tissue or in the foamy macrophages. Unusual variants include mucoceles with myxoglobulosis and papillary synovial metaplasia–like change. [19]
Extravasation of mucin along the mucosal-submucosal interface characterizes the superficial mucocele. The extravasation results in separation of the epithelium from its underlying submucosa and the formation of a subepithelial mucus-filled vesicle. A mild-to-moderate chronic inflammatory cell infiltration is observed in the underlying connective tissue, along with excretory ducts that may demonstrate ductal dilatation.
The cervical ranula appears identical to the mucus extravasation phenomenon. Biopsy of the lateral part of the neck may reveal only amorphous material with rare inflammatory cells, which stains positive for mucin.
The mucus retention cyst is a true cystic entity. It usually demonstrates a unicystic pattern; rarely, a multicystic appearance is identified. The cystic lining is composed of primarily cuboidal to columnar cells; however, mucous cells and squamous cells may be interspersed. Occasionally, oncocytoid and papillary changes of the epithelium lining are found. Typically, free mucin fills the central cavity, but mucus plugs and concentric layers of acellular calcification (sialolith) may be present. The cyst wall is composed of connective tissue with minimal inflammation, and it lacks the granular appearance of the mucus extravasation phenomenon. Atrophic sialadenitis with fibrosis and ductal ectasia may be found in the surrounding tissues.
Low-power photomicrograph of a mucocele with attenuation of the mucosal surface and pooling of mucus (hematoxylin-eosin, original magnification X40).
High-power photomicrograph of a mucocele with pooling of mucus and numerous foamy histiocytes (hematoxylin-eosin, original magnification X400).
Intermediate-power photomicrograph of an affected minor salivary gland lobule with atrophy of the acinar structures, ductal ectasia, and fibrosis (hematoxylin-eosin, original magnification X100).
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Classic example of a mucocele in a child. The fluctuant, translucent-blue nodule on the lower labial mucosa has been present for 6 weeks. Trauma from sucking on the lower lip was suspected to be the cause.
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Fluctuant submucosal nodule of the lower lip consistent with a mucocele.
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Surgical excision of the mucocele in Media File 2.
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Mucocele on the midline ventral surface of the tongue involving the glands of Blandin and Nuhn.
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Example of 2 superficial mucoceles of the soft palate in a 50-year-old woman. The red lesion represents a recently ruptured mucocele, and the translucent papular lesion represents an intact mucocele.
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Unilateral oral ranula in a young adult manifesting as a purple swelling.
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Ranula on the floor of the mouth with focal ulceration.
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Example of a cervical ranula with no oral involvement in an adult. The swelling developed after a car accident in which the individual had trauma to the face and neck.
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Low-power photomicrograph of a mucocele with attenuation of the mucosal surface and pooling of mucus (hematoxylin-eosin, original magnification X40).
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High-power photomicrograph of a mucocele with pooling of mucus and numerous foamy histiocytes (hematoxylin-eosin, original magnification X400).
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Intermediate-power photomicrograph of an affected minor salivary gland lobule with atrophy of the acinar structures, ductal ectasia, and fibrosis (hematoxylin-eosin, original magnification X100).
