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Dermatology > BENIGN NEOPLASMS
Mucous Cyst
Article Last Updated: Feb 7, 2007
AUTHOR AND EDITOR INFORMATION
Section 1 of 10  
Author: M Angelica Selim, MD, Associate Director of Dermatopathology, Departments of Pathology and Internal Medicine, Assistant Professor, Duke University Medical Center
Coauthor(s):
Christopher R Shea, MD, Professor and Chief, Section of Dermatology, Department of Medicine, University of Chicago
Editors: David P Fivenson, MD, Director, Wound Care Service, Department of Dermatology, Henry Ford Health System; Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University School of Medicine; Consulting Staff, Mountain View Dermatology, PA; Warren R Heymann, MD, Head, Division of Dermatology, Professor, Department of Internal Medicine, University of Medicine and Dentistry of New Jersey; Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University; William D James, MD, Paul R Gross Professor of Dermatology, University of Pennsylvania School of Medicine; Vice-Chair, Program Director, Department of Dermatology, University of Pennsylvania Health System
Author and Editor Disclosure
Synonyms and related keywords:
MC, mucocele, mucus extravasation phenomenon, mucus escape reaction, mucus retention cysts, mucous extravasation phenomenon, mucous escape reaction, mucous retention cysts
Background
A mucous cyst (MC) is a benign, common, mucus-containing cystic lesion of the minor salivary glands in the oral cavity. Some authors prefer the term mucocele since most of these lesions are not true cysts in the absence of an epithelial lining. The lesions can be located directly under the mucosa (superficial mucocele), in the upper submucosa (classic mucocele), or in the lower corium (deep mucocele). Two types of MCs occur based on the histologic features of the cyst wall: a mucous extravasation cyst formed by mucous pools surrounded by granulation tissue (92%) and a mucous retention cyst with an epithelial lining (8%).
Pathophysiology
The mechanism of formation of the MC is not totally clear; however, a traumatic etiology rather than an obstructive phenomenon is favored. Chaudhry et al showed that the escape of mucus into the surrounding tissue after severing the excretory salivary ducts led to the formation of the MC. The frequent location of the MC in the lateral aspect of the lower lip also supports the role of trauma as an etiologic factor. Although obstruction may play a role in the etiology of the MC, Chaudhry et al demonstrated that the ligation and cutting of the salivary glands' ducts in mice and rats did not create the MC.
Frequency
United States
The prevalence of an oral MC is 2.5 lesions per 1000 population.
Mortality/Morbidity
This benign condition is self-limited in most cases.
Race
A MC is most frequent in whites.
Sex
The sexual incidence is about equal.
Age
Although patients of all ages can be affected, more than one half of MC cases occur in those younger than 30 years. Mucous retention cysts are more frequent in older persons than in younger persons.
History
The clinical presentation varies by the type and the location of the lesion.
- People with superficial MCs may complain of single or multiple blisters that often spontaneously burst, leaving shallow ulcers.
- These lesions completely heal in a period of a few days.
- Sometimes, lesions recur in the same site.
- The classic MC presents as a shiny, dome-shaped papule that waxes and wanes over several months.
- An MC located in the deep soft tissue has a slow growth phase, resulting in a firm, deep mass.
- Rare cases have been described in the neck arising from ectopic salivary glands; these lesions are associated with cheilitis glandularis apostematosa.
Physical
The clinical presentation depends on the depth of the lesion.
- Superficial MC
- The mucus accumulates immediately below the mucosa, resulting in small translucent vesicles (0.1-0.4 cm in diameter) in the soft palate, the retromolar region, and the buccal mucosa.
- In time, these blisters burst spontaneously or by trauma, leaving shallow ulcers or erosions.
- Classic MC
- This form presents as a collection of mucous material in the upper submucosa producing a well-defined, mobile, and painless dome-shaped swelling.
- These lesions often exhibit a smooth, blue surface.
- The size varies from a few millimeters to several centimeters in diameter, but 75% of the lesions are smaller than 1 cm in diameter.
- Eventually, the surface of the lesion turns irregular and whitish due to multiple cycles of rupture and healing caused by trauma or puncture.
- The most frequent locations are in the lower lip, the floor of the mouth, the cheek, the palate, the retromolar fossa, and the dorsal surface of the tongue; however, these lesions spare the upper lip.
- Most of the larger lesions commonly affect the floor of the mouth; these are called ranula because of the similarity to the throat pouch of frogs. This collection of mucus can extend beyond the oral cavity and as far as the upper mediastinum or skull base.
- When the mucus accumulates in the deep soft tissues, the presentation is of an enlarging, painless mass assuming the pink coloration of the mucosa.
Causes
A traumatic etiology is favored. Animal models and the location of these lesions in areas of high traumatic exposure support this theory.
Aphthous Stomatitis
Lichen Planus
Lipomas
Other Problems to be Considered
Subepithelial MC
Aphthous stomatitis
Bullous lichen planus
Mucous membrane pemphigoid
Mucosal MC
Hemangioma
Deep MC
Neoplasm of the oral cavity
Fibroma
Neurofibroma
Schwannoma
Lipoma
Imaging Studies
- Consider additional studies to evaluate the anatomical extension of a deep MC.
- Plain radiographs show nonspecific soft-tissue density.
- Sonograms show a rounded or lobulated hypoechoic mass with well-defined borders.
- CT scans frequently demonstrate a well-defined water density mass.
- MRI shows a homogeneous low-intensity lesion on T1-weighted images. T2-weighted images reveal an increased signal and sharp borders.
Other Tests
- Fine needle aspiration is commonly used in the evaluation of deep lesions. The aspirate smears usually show sparsely cellular mucoid material with a few histiocytes and inflammatory cells.
Histologic Findings
The specimens show collections of eosinophilic mucus admixed with some inflammatory cells in the upper portion or deep submucosa (see Image 1). The mucin is periodic acid-Schiff (PAS) positive, diastase resistant, colloidal iron and Alcian blue positive (pH 2.5), and hyaluronidase resistant. These properties of staining indicate a nonsulfated acid mucopolysaccharide, such as sialomucin. The mucin has an epithelial rather than a fibroblastic origin. Granulation tissue with an acute inflammatory infiltrate mainly forms the wall of the cystlike cavity (see Image 2). In time, the wall of the cyst consists of a variable number of fibrocytes and chronic inflammatory cells. An epithelial lining, most likely derived from the minor salivary ducts, is rarely identified in these biopsy specimens. The salivary gland presents deeper in the connective tissue. This lesion may have lymphocytic infiltrates, ductal distention, degeneration of acini, andvarious degrees offibrosis. Secondary changes have also been recognized in the epidermis or the mucosa (eg, parakeratosis, acanthosis, atrophy). Transmucosal elimination of the mucin has been reported. The superficial mucocele is a subepithelial blister. The roof of the lesion is formed by attenuated mucosa, while the floor consists of corium with mild inflammatory infiltrate. Some lesions can appear to be intraepithelial blisters due to the regeneration of epithelium across the denuded base. The content of the lesion consists of variable amounts of eosinophilic mucus admixed with polymorphonuclear cells. Salivary gland ducts may open into the floor of the blister, and salivary gland lobules may be identified in deeper tissues.
Medical Care
Patients with superficial MCs require reassurance only. Partial or total electrodesiccation and intralesional injections of triamcinolone acetonide have been reported as treatments of an MC; however, these are not routinely used.
Surgical Care
The minor salivary gland should be excised, just as in cases with persistent irritation.
- The treatment of choice for a deep MC and the classic form is surgical excision, which should include the immediate adjacent glandular tissue.
- Cryosurgery with liquid nitrogen spray or cryoprobe is an alternative therapeutic modality. After day 4 to week 1, a necrotic surface is observed in the treated area. The latter separates from the surrounding mucosa in 1-2 weeks, exposing a new epithelialized surface. The advantages of the procedure include a simple application, minor discomfort during the procedure, and a low incidence of complications (eg, secondary infection, hemorrhage); however, the possibility of recurrence exists.
- Another therapeutic strategy is argon laser treatment typically administrated at a constant pulse duration of 0.3 seconds, using a laser beam diameter of 1.5-2 mm and a power setting of 2-3 W. Lesions presenting as firm nodules are treated with a continuous exposure and a power setting of 2.5-3.5 W. The necrotic area posttreatment is well defined by day 8-12, with complete wound healing in approximately 2 weeks. The only reported complications are swelling and mild discomfort for up to 10 days. The advantages of argon laser over cryosurgery consist of less discomfort in the postoperative period, less edema and irritation, and a reduced healing time. A disadvantage of this therapeutic alternative is the requirement of specialized equipment.
- The use of carbon dioxide laser in the treatment of mucoceles has been described. It has the advantages of allowing precise surgical technique, lack of bleeding for a clear operation field, and minimal wound contraction and scarring. A disadvantage is the requirement of specialized equipment.
Consultations
- Dermatologist
- Dermatologic surgeon
- Oral medicine specialist
- Oral surgeon
Local injection of corticosteroids has been used; however, a high frequency of recurrence is associated with this modality of treatment.
Drug Category: Corticosteroids
These agents have anti-inflammatory properties and cause profound and varied metabolic effects. They modify the body's immune response to diverse stimuli.
| Drug Name | Triamcinolone (Aristocort) |
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| Description | For inflammatory dermatosis responsive to steroids; decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing capillary permeability. Intramuscular injection may be used for widespread skin disorder, or intralesional injections may be used for localized skin disorder. |
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| Adult Dose | 2.5-10 mg/mL intralesional |
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| Pediatric Dose | <12 years: Not established
>12 years: Administer as in adults |
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| Contraindications | Documented hypersensitivity; fungal, viral, and bacterial skin infections |
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| Interactions | Coadministration with barbiturates, phenytoin, and rifampin decreases effects |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Multiple complications (eg, severe infections, hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression) may occur; abrupt discontinuation of glucocorticoids may cause adrenal crisis |
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Complications
- Secondary infection and local bleeding have been reported as rare complications.
- Traumatic neuroma may occur as a sequela following laser or cryosurgery.
Prognosis
- Patients with MCs have an excellent prognosis; however, recurrence is common in the absence of resection of the associated salivary gland.
| Media file 1:
The submucosa shows a mucin-filled, cystlike cavity below the squamous mucosa. Minor salivary gland lobules are present in the submucosa. |
 |  View Full Size Image | |
Media type: Photo
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| Media file 2:
The wall of the lesion is usually formed by connective tissue, inflammatory cells, foamy macrophages (lower left corner), and salivary gland acini (upper right corner). |
 | View Full Size Image | |
Media type: Photo
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Mucous Cyst excerpt Article Last Updated: Feb 7, 2007
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