Oral mucocele (also mucous extravasation cyst, mucous cyst of the oral mucosa, and mucous retention and extravasation phenomena) is a condition caused by two related phenomena - mucus extravasation phenomenon and mucous retention cyst. Mucous extravasation phenomenon is a swelling of

connective tissue Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...

consisting of a collection of fluid called

mucus Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...

. This occurs because of a ruptured

salivary gland The salivary glands in many vertebrates including mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of min ...

duct The word duct is derived from the Latin word for ''led/leading''. It may refer to: * Duct (anatomy), various ducts in anatomy and physiology ** Tear duct, which carry tears to the eyes * Duct (HVAC), for transfer of air between spaces in a struct ...

usually caused by local trauma (damage) in the case of mucous extravasation phenomenon and an obstructed or ruptured salivary duct in the case of a mucus retention cyst. The mucocele has a bluish, translucent color, and is more commonly found in children and young adults. Although these

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by injury or diseases. The term ''Lesion'' is derived from the Latin meaning "injury". Lesions may occur in both plants and animals. Types There is no de ...

s are often called

cysts A cyst is a closed Wikt:sac, sac, having a distinct Cell envelope, envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac ...

, mucoceles are not true cysts because they have no

epithelial Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...

lining. Rather, they are polyps.

Signs and symptoms

The size of oral mucoceles vary from 1 mm to several centimeters and they usually are slightly transparent with a blue tinge. On palpation, mucoceles may appear fluctuant, but can also be firm. Their duration lasts from days to years, and may have recurrent swelling with occasional rupturing of its contents. Mucocelesimple

Locations

The most common location to find a mucocele is the inner surface of the lower lip. It can also be found on the inner side of the cheek (known as the

buccal mucosa The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed ''lamina propria''. The oral cavity has sometimes been describ ...

), on the anterior ventral

tongue The tongue is a Muscle, muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for chewing and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper s ...

, and the floor of the

mouth A mouth also referred to as the oral is the body orifice through which many animals ingest food and animal communication#Auditory, vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also t ...

. When found on the floor of the mouth, the mucocele is referred to as a ranula. They are rarely found on the upper lip. As their name suggests, they are basically mucus-lined cysts and they can also occur in the

paranasal sinus Paranasal sinuses are a group of four paired skeletal pneumaticity, air-filled spaces that surround the nasal cavity. The maxillary sinuses are located under the eyes; the frontal sinuses are above the eyes; the Ethmoid sinus, ethmoidal sinuses a ...

es, most commonly the

frontal sinus The frontal sinuses are one of the four pairs of paranasal sinuses that are situated behind the brow ridges. Sinuses are mucosa-lined airspaces within the bones of the face and skull. Each opens into the anterior part of the corresponding middle ...

es, the frontoethmoidal region, and the

maxillary sinus The pyramid-shaped maxillary sinus (or antrum of Nathaniel Highmore (surgeon), Highmore) is the largest of the paranasal sinuses, located in the maxilla. It drains into the middle meatus of the noseHuman Anatomy, Jacobs, Elsevier, 2008, page 209- ...

Sphenoid sinus The sphenoid sinus is a paired paranasal sinus in the body of the sphenoid bone. It is one pair of the four paired paranasal sinuses.Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, page 64 The two sphenoid sinuse ...

involvement is extremely rare. When the lumen of the

vermiform appendix The appendix (: appendices or appendixes; also vermiform appendix; cecal (or caecal, cæcal) appendix; vermix; or vermiform process) is a finger-like, blind-ended tube connected to the cecum, from which it develops in the embryo. The cecum ...

of the intestine gets blocked due to any factor, a mucocele can also form there.

Variations

A variant of a mucocele is found on the

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...

, retromolar pad, and posterior buccal mucosa. Known as a "superficial mucocele", this type presents as single or multiple

vesicles Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry), a supramolecular assembly of lipid molecules, like a cell membrane * Synaptic vesicle In a neuron, synaptic vesicles (or neurotransmitter vesicles) s ...

and bursts into an ulcer. Despite healing after a few days, superficial mucoceles recur often in the same location. Other causes of bumps inside lips are

aphthous ulcer Aphthous stomatitis, or recurrent aphthous stomatitis (RAS), commonly referred to as a canker sore or salt blister, is a common condition characterized by the repeated formation of benignity, benign and non-contagious disease, contagious mouth ...

lipoma A lipoma is a benign tumor made of adipose tissue, fat tissue. They are generally soft to the touch, movable, and painless. They usually occur just under the skin, but occasionally may be deeper. Most are less than in size. Common locations inc ...

, benign tumors of salivary glands, submucous abscesses, and haemangiomas.

Diagnosis

Microscopically, mucoceles appears as

granulation tissue Granulation tissue is new connective tissue and microscopic blood vessels that form on the surfaces of a wound during the healing process. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size ...

surrounding mucin. Since

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

occurs concurrently,

neutrophil Neutrophils are a type of phagocytic white blood cell and part of innate immunity. More specifically, they form the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. Their functions vary in differe ...

s and foamy

histiocyte A histiocyte is a vertebrate cell that is part of the mononuclear phagocyte system (also known as the reticuloendothelial system or lymphoreticular system). The mononuclear phagocytic system is part of the organism's immune system. The histiocy ...

s usually are present. On a

CT scan A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

, a mucocele is fairly homogenous, with an attenuation of about 10-18

Hounsfield unit The Hounsfield scale ( ), named after Sir Godfrey Hounsfield, is a quantitative scale for describing radiodensity. It is frequently used in CT scans, where its value is also termed CT number. Definition The Hounsfield unit (HU) scale is a linear t ...

Classification

Both mucous retention and extravasation phenomena are classified as salivary gland disorders.

Treatment

Some mucoceles spontaneously resolve on their own after a short time. Others are chronic and require surgical removal. Recurrence is possible, thus the adjacent salivary gland may be excised as a preventive measure. Hence surgical removal of cyst is treatment of choice. Several types of procedures are available for the surgical removal of mucoceles. These include laser and minimally invasive techniques, which means recovery times are reduced drastically. Micromarsupialization is an alternative procedure to surgical removal. It uses silk sutures in the dome of a cyst to allow new epithelialized drainage pathways. It is simpler, less traumatic, and well tolerated by patients, especially children. A nonsurgical option that may be effective for a small or newly identified mucocele is to rinse the mouth thoroughly with salt water (one tablespoon of salt per cup) four to six times a day for a few days. This may draw out the fluid trapped underneath the skin without further damaging the surrounding tissue. If the mucocele persists, individuals should see a doctor to discuss further treatment. Smaller cysts may be removed by laser treatment, but larger cysts may have to be removed surgically.

References

External links

{{Oral pathology Salivary gland pathology Conditions of the mucous membranes Mucinoses