eMedicine Specialties > Dermatology > Benign Neoplasms

Mucous Cyst

Christopher R Shea, MD, Professor and Chief, Section of Dermatology, Department of Medicine, University of Chicago
Markus D Boos, PhD, Medical Scientist Training Program, Pritzker School of Medicine, University of Chicago

Updated: Oct 30, 2009

Introduction

Background

A mucous cyst 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 mucous cyst), in the upper submucosa (classic mucous cyst), or in the lower corium (deep mucous cyst). Two types of mucous cysts 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%).¹

Pathophysiology

The mechanism of mucous cyst formation is unclear; however, a traumatic etiology rather than an obstructive phenomenon is considered more likely. Chaudhry et al showed that the escape of mucus into the surrounding tissue after severing the excretory salivary ducts led to mucous cyst formation.² The frequent location of the mucous cyst 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 mucous cyst, Chaudhry et al demonstrated that ligation and cutting of the salivary glands' ducts in rodents did not result in mucous cyst formation.² Lymphatic vessels may also contribute to the early stages of mucous cyst development. Specifically, the growing mucous cyst may induce a pressure gradient that causes lymphatics to swell with interstitial fluid, eventually rupturing and delivering this fluid back to the mucous cyst.³

Frequency

United States

The prevalence of oral mucous cyst is 2.5 lesions per 1000 population.⁴

Mortality/Morbidity

Mucous cyst, a benign condition, is self-limited in most cases.

Race

Mucous cysts are most frequent in whites.

Sex

The incidence of mucous cyst is about equal in males and females.⁵

Age

Although patients of all ages can be affected, more than half of mucous cyst cases occur in those younger than 30 years. Mucous retention cysts are more frequent in older persons; conversely, the majority of mucous cysts in younger patients represent the extravasation type.⁶ Mucous cysts of the glands of Blandin-Nuhn (present on the ventral surface of the tongue) appear to be more prominent in young patients.⁶

Clinical

History

The clinical presentation varies by the type and the location of the lesion.

• People with superficial mucous cysts 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 presentation of mucous cysts is a shiny, dome-shaped papule that waxes and wanes over several months.
• A mucous cyst 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.
• The appearance of superficial mucous cysts as a consequence of chronic graft versus host disease has been reported in patients receiving allogeneic bone marrow transplants. They typically are asymptomatic and therefore may not be identified.⁷

Physical

The clinical presentation of mucous cysts depends on the depth of the lesion.

• Superficial mucous cyst
  • The mucus accumulates immediately below the mucosa, resulting in small translucent vesicles (0.1-0.4 cm in diameter) in the soft palate, retromolar region, and buccal mucosa.
  • In time, these blisters may burst spontaneously or by trauma, leaving shallow ulcers or erosions.
• Classic mucous cyst
  • This form presents as a collection of mucus in the upper submucosa producing a well-defined, mobile, painless, dome-shaped swelling.
  • These lesions often exhibit a smooth, blue surface.
  • The size varies from a few millimeters to several centimeters in diameter; 75% of the lesions are less than 1 cm in diameter.
  • Eventually, the surface turns irregular and whitish due to multiple cycles of rupture and healing caused by trauma or puncture.
  • The most frequent locations are the lower lip, floor of the mouth, cheek, palate, retromolar fossa, and dorsum of the tongue; the upper lip is usually spared.
  • Larger lesions commonly affect the floor of the mouth; these are called ranulas because of the similarity to the throat pouch of frogs. A ranula can extend beyond the oral cavity, 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 for mucous cysts. Animal models and the location of these lesions in areas of high traumatic exposure support this theory.^8,9,10,11

Differential Diagnoses

Aphthous Stomatitis
Lichen Planus
Lipomas

Other Problems to Be Considered

Subepithelial mucous cyst
Aphthous stomatitis
Bullous lichen planus
Mucous membrane pemphigoid

Mucosal mucous cyst
Hemangioma
Deep mucous cyst
Neoplasm of the oral cavity
Fibroma
Neurofibroma
Schwannoma
Lipoma

Workup

Imaging Studies

• Consider additional studies to evaluate the anatomical extension of a deep mucous cyst.
  • Plain radiographs show nonspecific soft-tissue density.
  • Sonograms show a rounded or lobulated, hypoechoic mass with well-defined borders.
  • CT scans frequently demonstrate a circumscribed 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 Media File 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.¹² The mucin has an epithelial rather than a fibroblastic origin.

The submucosa shows a mucin-filled, cystlike cavity below the squamous mucosa. Minor salivary gland lobules are present in the submucosa.

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).

Treatment

Medical Care

Patients with asymptomatic, superficial mucous cysts may require reassurance only. Partial or total electrodesiccation and intralesional injections of triamcinolone acetonide have been reported as treatments for mucous cysts. Topical clobetasol propionate 0.05% has been reported as an effective intervention for multiple, recurrent mucous cysts.¹³

Surgical Care

For definitive management, if indicated, the minor salivary gland may be excised, just as in cases with persistent irritation.

• The treatment of choice for a deep mucous cyst 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.^14,15 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.¹⁶ 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 appears to be a superior treatment modality for mucous cyst, with minimal recurrence.¹⁷ It has the advantages of allowing precise surgical technique, lack of bleeding for a clear operation field, minimal wound contraction and scarring, and a short operative time.^18,19,20 As such, it has been proposed to be particularly useful in the treatment of those who are intolerant of long procedures, including children. A disadvantage is the requirement of expensive, specialized equipment, and necessary protection for both the patient and physician performing the laser vaporization.¹⁹
• Erbium laser treatment has also been described in a pediatric patient, with excellent results.²¹

Consultations

• Dermatologist
• Dermatologic surgeon
• Oral medicine specialist
• Oral surgeon

Medication

Local injection of corticosteroids has been used for treating mucous cysts; however, a high frequency of recurrence is associated with this modality of treatment.

Corticosteroids

These agents have anti-inflammatory properties and cause profound and varied metabolic effects. They modify the body's immune response to diverse stimuli.

Triamcinolone (Aristocort)

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.

Dosing

Adult

2.5-10 mg/mL intralesional

Pediatric

<12 years: Not established
>12 years: Administer as in adults

Interactions

Coadministration with barbiturates, phenytoin, and rifampin decreases effects

Contraindications

Documented hypersensitivity; fungal, viral, and bacterial skin infections

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

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

Follow-up

Complications

• Secondary infection and local bleeding have been reported as rare complications.
• Traumatic neuroma may occur as a sequela following laser or cryosurgery.²²

Prognosis

• Patients with mucous cysts have an excellent prognosis; however, recurrence is common in the absence of resection of the associated salivary gland.

Multimedia

Media file 1: The submucosa shows a mucin-filled, cystlike cavity below the squamous mucosa. Minor salivary gland lobules are present in the submucosa.

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).

References

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Keywords

mucous cyst, MC, mucocele, mucus extravasation phenomenon, mucus escape reaction, mucus retention cysts, mucous extravasation phenomenon, mucous escape reaction, mucous retention cysts

Contributor Information and Disclosures

Author

Christopher R Shea, MD, Professor and Chief, Section of Dermatology, Department of Medicine, University of Chicago
Christopher R Shea, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Society of Dermatopathology, Arthur Purdy Stout Society, Association of Professors of Dermatology, Chicago Dermatological Society, Dermatology Foundation, Illinois Dermatological Society, International Society of Dermatopathology, and Society for Investigative Dermatology
Disclosure: Nothing to disclose.

Coauthor(s)

Markus D Boos, PhD, Medical Scientist Training Program, Pritzker School of Medicine, University of Chicago
Disclosure: Nothing to disclose.

Medical Editor

David P Fivenson, MD, Associate Director, St Joseph Mercy Hospital Dermatology Program, Ann Arbor, Michigan
David P Fivenson, MD is a member of the following medical societies: American Academy of Dermatology, Medical Dermatology Society, Michigan Dermatological Society, Michigan State Medical Society, Photomedicine Society, Society for Investigative Dermatology, and Wound Healing Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University School of Medicine; Consulting Staff, Mountain View Dermatology, PA
Richard P Vinson, MD is a member of the following medical societies: American Academy of Dermatology, Association of Military Dermatologists, Texas Dermatological Society, and Texas Medical Association
Disclosure: Nothing to disclose.

Managing Editor

Warren R Heymann, MD, Head, Division of Dermatology, Professor, Department of Internal Medicine, University of Medicine and Dentistry of New Jersey
Warren R Heymann, MD is a member of the following medical societies: American Academy of Dermatology, American Society of Dermatopathology, and Society for Investigative Dermatology
Disclosure: Nothing to disclose.

CME Editor

Catherine M Quirk, MD, Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania
Catherine M Quirk, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology
Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology
Disclosure: Nothing to disclose.

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, M. Angelica Selim, MD, and previous Chief Editor, William D. James, MD, to the development and writing of this article.

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