Preauricular sinuses and cysts result from developmental defects of the first and second pharyngeal arches. This and other congenital ear malformations are sometimes associated with renal anomalies. They may be present in Beckwith–Wiedemann syndrome, and in rare cases, they may be associated with branchio-oto-renal syndrome.

Occasionally a preauricular sinus or cyst can become infected.

Most preauricular sinuses are asymptomatic, and remain untreated unless they become infected too often. Preauricular sinuses can be excised with surgery which, because of their close proximity to the facial nerve, is performed by an appropriately trained, experienced surgeon (e.g. a specialist General Surgeon, a Plastic Surgeon, an otolaryngologist (Ear, Nose, Throat surgeon) or an Oral and Maxillofacial Surgeon).

Most branchial cleft cysts present as a smooth, slowly enlarging lateral neck mass that may increase in size after an upper respiratory tract infection. The fistulas, when present, are asymptomatic, but may become infected.

The nasopalatine cyst is the most common non-odontogenic cyst of the oral cavity, at an estimated occurrence rate of 73%.

Nasopalatine duct cysts usually present as asymptomatic palatal swellings, but they may rarely be accompanied by pain and/or purulent discharge. The cysts are generally treated by .

Thyroglossal duct cysts most often present with a palpable asymptomatic midline neck mass above the level of the hyoid bone. The mass on the neck moves during swallowing or on protrusion of the tongue because of its attachment to the tongue via the tract of thyroid descent. Some patients will have neck or throat pain, or dysphagia.

The persistent duct or sinus can promote oral secretions, which may cause cysts to become infected. Up to half of thyroglossal cysts are not diagnosed until adult life. The tract can lie dormant for years or even decades, until some kind of stimulus leads to cystic dilation. Infection can sometimes cause the transient appearance of a mass or enlargement of the cyst, at times with periodic recurrences. Spontaneous drainage may also occur. Differential diagnosis are ectopic thyroid, enlarged lymph nodes, dermoid cysts and goiter.

Thyroglossal cyst usually presents as a midline neck lump (in the region of the hyoid bone) that is usually painless, smooth and cystic, though if infected, pain can occur. There may be difficulty breathing, dysphagia (difficulty swallowing), or dyspepsia (discomfort in the upper abdomen), especially if the cyst becomes large.

The most common location for a thyroglossal cyst is midline or slightly off midline, between the isthmus of the thyroid and the hyoid bone or just above the hyoid bone. A thyroglossal cyst can develop anywhere along a thyroglossal duct, though cysts within the tongue or in the floor of the mouth are rare.A thyroglossal cyst will move upwards with protrusion of the tongue.Thyroglossal cysts are associated with an increased incidence of ectopic thyroid tissue. Occasionally, a lingual thyroid can be seen as a flattened strawberry-like lump at the base of the tongue.

A branchial cleft cyst is a cyst in the skin of the lateral part of the neck. It can but does not necessarily have an opening to the skin surface called a fistula. The cause is usually a developmental abnormality arising in the early prenatal period, typically failure of obliteration of the second branchial cleft, i.e. failure of fusion of the second and third branchial arches. Less commonly, the cysts can develop from the first, third, or fourth clefts, and their location and the location of associated fistulas differs accordingly.

Oroantral fistula (OAF) is an abnormal condition of the face where the maxillary sinus is exposed to the oral cavity through an epithelialised fistula. This term signifies pathology and it is not to be confused with oroantral communication (OAC). OAC if left untreated can either heal spontaneously or progress into OAF. The fistulous opening may be situated on the alveolus.

Clinical examination and x rays can help diagnose the condition. For examples :

- Valsalva test (nose blowing test): Ask the patient to pinch the nostrils together and open the mouth, then blow gently through the nose. Observe if there is passage of air or bubbling of blood in the post extraction alveolus as the trapped air from closed nostrils is forced into the mouth through any oroantral communication. Gentle suction applied to the socket often produces a characteristic hollow sound.

- Perform a complete extra- and intra-oral examination using a dental mirror under good lighting, look for granulation tissue in the socket and openings into the antrum.

- Panoramic radiograph or paranasal computed tomography can help to locate the fistula, the size of it and to determine the presence of sinusitis and other foreign bodies. Other methods like radiographs (occipitomental, OPG and periapical views) can also be used to confirm the presence of any oroantral fistulas.

- To test the patency of communication the patient is asked to rinse the mouth or water is flushed in the tooth socket.

- Unilateral epistaxis is seen in case of collection of blood in the sinus cavity.

- Do not probe or irrigate the site, because it may lead to sinusitis or push foreign bodies, such as contaminated fragments, or oral flora further into the antrum. Hence, leading to the formation of a new fistula or widen an existing one.

An infected thyroglossal duct cyst can occur when it is left untreated for a certain amount of time or simply when a thyroglossal duct cyst hasn't been suspected. The degree of infection can be examined as major rim enhancement has occurred, located inferior to the hyoid bone. Soft tissue swelling occurs, along with airway obstruction and trouble swallowing, due to the rapid enlargement of the cyst.

With infections, there can be rare cases where an expression of fluid is projected into the pharynx causing other problems within the neck.

The general presentation is of a skin-covered nodule, papule, or nodule of the skin surface, usually immediately anterior to the auricle. However, it may be anywhere within the periauricular tissues. Bilateral presentation can be seen.

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.

Gingival cyst of adult is a rare condition. The incidence is less than 0.5%. It is formed from the rests of dental lamina. It is found in the soft tissues on the buccal and labial portions of the jaw. It usually occurs on the facial gingiva as a single small flesh colored swelling, sometimes with a bluish hue due to the cystic fluid. Sometimes, it may occur in cluster, either unilaterally or bilaterally or on the lingual surface of the alveolar process. It is most commonly seen in the canine and premolar regions of the mandible, and are sometimes confused with lateral periodontal cysts. It is not normally problematic, but when it grows larger, it can cause some discomfort. It can be removed by simple surgical excision. They are developed late in life, generally up to the sixth decade of age.

The median palatal cyst is a rare cyst that may occur anywhere along the median palatal raphe. It may produce swelling because of infection and is treated by excision or surgical removal.

Some investigators now believe that this cyst represents a more posterior presentation of a nasopalatine duct cyst, rather than a separate cystic degeneration of epithelial rests at the line of fusion of the palatine shelves.

Cysts rarely cause any symptoms, unless they become secondarily infected. The signs depend mostly upon the size and location of the cyst. If the cyst has not expanded beyond the normal anatomical boundaries of the bone, then there will be no palpable lump outside or inside the mouth. The vast majority of cysts expand slowly, and the surrounding bone has time to increase its density around the lesion, which is the body's attempt to isolate the lesion. Cysts that have expanded beyond the normal anatomic boundaries of a bone are still often covered with a thin layer of new bone. At this stage, there may be a sign termed "eggshell cracking", where the thinned cortical plate cracks when pressure is applied. A lump may be felt, which may feel hard if there is still bone covering the cyst, or fluctuant if the cyst has eroded through the bone surrounding it. A cyst may become acutely infected, and discharge into the oral cavity via a sinus. Adjacent teeth may be loosened, tilted or even moved bodily. Rarely, roots of teeth are resorbed, depending upon the type of cyst. The inferior alveolar nerve runs through the mandible and supplies sensation to the lower lip and chin. As most cysts expand slowly, there will be no altered sensation (anesthesia or paraesthesia), since the inferior alveolar canal is harmlessly enveloped or displaced over time. More aggressive cysts, or acute infection of any cyst may cause altered sensation.

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), on the anterior ventral tongue, and the floor of the mouth. 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 sinuses most commonly the frontal sinuses, the frontoethmoidal region and also in the maxillary sinus. Sphenoid sinus involvement is extremely rare.

When the lumen of the vermiform appendix gets blocked due to any factor, again a mucocele can form.

Pilonidal cysts are itchy and are often very painful, and typically occur between the ages of 15 and 35. Although usually found near the coccyx, the condition can also affect the navel, armpit or genital region, though these locations are much rarer.

Symptoms include:

- Pain/discomfort or swelling above the anus or near the tailbone that comes and goes

- Opaque yellow (purulent) or bloody discharge from the tailbone area

- Unexpected moisture in the tailbone region

- Discomfort with sitting on the tailbone, doing sit-ups or riding a bike (any activities that roll over the tailbone area)

Some people with a pilonidal cyst will be asymptomatic.

The lesions presents as a nodule or papule, either sessile or pedunculated. They may be soft or have a cartilaginous structure. By histologic examination, it is a recapitulation of normal external auricle. There will be skin, cartilaginous structures, and cartilage (although the later is not seen in all variants of this disorder). Some investigators believe that the tragus is the only hillock which is derived from the first branchial arch. This is clearly suggestive that true cases of Accessory Auricle represent a true duplication of the hillocks that were part of the second branchial arch. The second ear appears as a mirror image folded forward and lying on the posterior cheek.

A cyst is a pathological epithelial lined cavity that fills with fluid or soft material and usually grows from internal pressure generated by fluid being drawn into the cavity from osmosis (hydrostatic pressure). The bones of the jaws, the mandible and maxilla, are the bones with the highest prevalence of cysts in the human body. This is due to the abundant amount of epithelial remnants that can be left in the bones of the jaws. The enamel of teeth is formed from ectoderm (the precursor germ layer to skin and mucosa), and so remnants of epithelium can be left in the bone during odontogenesis (tooth development). The bones of the jaws develop from embryologic processes which fuse together, and ectodermal tissue may be trapped along the lines of this fusion. This "resting" epithelium (also termed cell rests) is usually dormant or undergoes atrophy, but, when stimulated, may form a cyst. The reasons why resting epithelium may proliferate and undergo cystic transformation are generally unknown, but inflammation is thought to be a major factor. The high prevalence of tooth impactions and dental infections that occur in the bones of the jaws is also significant to explain why cysts are more common at these sites.

Cysts that arise from tissue(s) that would normally develop into teeth are referred to as odontogenic cysts. Other cysts of the jaws are termed non-odontogenic cysts. Non-odontogenic cysts form from tissues other than those involved in tooth development, and consequently may contain structures such as epithelium from the nose. As the cyst grows from hydraulic pressure it causes the bone around it to resorb, and may cause movement of teeth or other vital structures such as nerves and blood vessels, or resorb the roots of teeth. Most cysts do not cause any symptoms, and are discovered on routine dental radiographs.

Some cysts may not require any treatment, but if treatment is required, it usually involves some minor surgery to partially or completely remove the cyst in a one or two-stage procedure.

A sinus tract, or small channel, may originate from the source of infection and open to the surface of the skin. Material from the cyst may drain through the pilonidal sinus. A pilonidal cyst is usually painful, but with draining, the patient might not feel pain.

Gingival cyst (or dental lamina cyst) is a type of cysts of the jaws that originates from the dental lamina and is found in the mouth parts. It is a superficial cyst in the alveolar mucosa. It can be seen inside the mouth as small and whistish bulge. Depending on the ages in which they develop, the cysts are classsfied into gingival cyst of newborn (or infant) and gingival cyst of adult. Structurally, the cyst is lined by thin epithelium and shows a lumen usually filled with desquamated keratin, occasionally containing inflammatory cells. The nodes are formes as a result of cystic degeneration of epithelial rests of the dental lamina (called the rests of Serres).

Gingival cyst was first described by a Czech physician Alois Epstein in 1880. In 1886, a German physician Heinrich Bohn described another type of cyst. Alfred Fromm introduced the classification of gingival cysts in 1967. According to him, gingival cysts of newborns can be further classsified based on their specific origin of the tissues as Epstein’s pearls, Bohn’s nodules and dental lamina cysts.

Periapical cysts begin as asymptomatic and progress slowly. Subsequent infection of the cyst causes swelling and pain. Initially, the cyst swells to a round hard protrusion, but later on the body resorbs some of the cyst wall, leaving a softer accumulation of fluid underneath the mucous membrane.

Larger cysts may cause bone expansion or displace roots. Discoloration of the affected tooth may also occur. Patient will present negative results to electric and ice test of the affected tooth but will be sensitive to percussion. Surrounding gingival tissue may experience lymphadenopathy. The alveolar plate may exhibit crepitus when palpated.

Periapical cysts exist in two structurally distinct classes:

Periapical true cysts - cysts containing cavities entirely surrounded in epithelial lining. Resolution of this type of cyst requires surgical treatment such as a cystectomy.

Periapical pocket cysts - epithelium lined cavities that have an opening to the root canal of the affected tooth. Resolution may occur after traditional root canal therapy.

Periapical cysts comprise approximately 75% of the types of cysts found in the oral region. The ratio of individuals diagnosed with periapical cysts is 3:2 male to female, as well as individuals between 20 and 60 years old. Periapical cysts occur worldwide.

Types of Periapical cysts:

Apical: 70%

Lateral: 20%

Residual: 10%

Buccal bifurcation cyst is an inflammatory odontogenic cyst, of the paradental cysts family, that typically appears in the buccal bifurcation region of the mandibular first molars in the second half of the first decade of life. Infected cysts may be associated with pain.

A median mandibular cyst is a type of cyst that occurs in the midline of the mandible, thought to be created by proliferation and cystic degeneration of resting epithelial tissue that is left trapped within the substance of the bone during embryologic fusion of the two halves of the mandible, along the plane of fusion later termed the symphysis menti. A ture median mandibular cyst would therefore be classified as a non-odontogenic, fissural cyst. The existence of this lesion as a unique clinical entity is controversial, and some reported cases may have represented misdiagnosed odontogenic cysts, which are by far the most common type of intrabony cyst occurring in the jaws. It has also been suggested that the mandible develops as a bilobed proliferation of mesenchyme connected with a central isthmus. Therefore, it is unlikely that epithelial tissue would become trapped as there is no ectoderm separating the lobes in the first instance.