A persistent thyroglossal duct is a usually benign medical condition in which the thyroglossal duct, a structure usually only found during embryonic development, fails to atrophy. The duct persists as a midline structure forming an open connection between the back of the tongue and the thyroid gland.This opening can lead to fluid accumulation and infection, which necessitate the removal of the duct.

In one report, about 20% of individuals with mealtime syndrome had strictures upon sialography. For unknown reasons, strictures seem to be more common in females.

Studies done on cadavers claim persistent thyroglossal ducts can be completely asymptomatic and found in 7% of the human adult population. However, the continued presence of the duct can often lead to complications due to infections and fluid buildup. The glands in the mucosa of the duct will continue their secretions until the fluid forms a cyst or exit the duct via the opening in the foramen cecum. Local infections, such as colds, tonsillitis, or inflammation of the lymph nodes in the area can also lead to the accumulation of fluid within the duct. Even if the cyst forms as secondary to another infection and improved after antibiotics, it will often reoccur and require treatment.

Three-fourths of abnormalities within a persistent thyroglossal duct involve the formation of a cyst. If a persistent thyroglossal duct becomes fluid filled it will form a thyroglossal duct cyst, which accounts for 70% of congenital neck masses and is the most likely diagnosis if the mass is along the midline of the neck. These cysts are often diagnosed in children under the age of ten and have no particular gender prevalence. The cysts are normally asymptomatic at this age and are noticed because of the swelling that will move if the patient swallows. Over 80% of these cysts are located at or below the hyoid bone.

Very rarely, the persistent duct can become cancerous, called thyroglossal duct carcinoma. In the case of thyroglossal duct carcinoma, the cancerous cells are ectopic thyroid tissue that has been deposited along the thyroglossal duct and will present as a papillary carcinoma. However, the cells are less likely to metastasize in the cyst, than if they were present in the actual thyroid gland.

The other fourth of abnormalities presents as draining abscess. This is from an infection that will rupture through the skin to allow for adequate drainage of the infected area.

The thyroglossal tract arises from the foramen cecum at the junction of the anterior two-thirds and posterior one-third of the tongue. Any part of the tract can persist, causing a sinus, fistula or cyst. Most fistulae are acquired following rupture or incision of the infected thyroglossal cyst. A thyroglossal cyst is lined by pseudostratified, ciliated columnar epithelium while a thyroglossal fistula is lined by columnar epithelium.

Thyroglossal Duct Cysts are a birth defect. During embryonic development, the thyroid gland is being formed, beginning at the base of the tongue and moving towards the neck canal, known as the thyroglossal duct. Once the thyroid reaches its final position in the neck, the duct normally disappears. In some individuals, portions of the duct remain behind, leaving small pockets, known as cysts. During a person's life, these cyst pockets can fill with fluids and mucus, enlarging when infected, presenting the thyroglossal cyst.

Salivary gland atresia is congenital blockage or absence of the orifice of a major salivary gland duct or part of the duct itself.

It is a very rare condition. The submandibular salivary gland duct is usually involved, having failed to cannulate during embryological development. The condition first becomes apparent in the first few days after birth where a submandibular swelling caused by a retention cyst is noticed.

Two percent of women will have a Bartholin's gland cyst at some point in their lives. They occur at a rate of 0.55 per 1000 person-years and in women aged 35–50 years at a rate of 1.21 per 1000 person-years. The incidence of Bartholin duct cysts increases with age until menopause, and decreases thereafter. Hispanic women may be more often affected than white women and black women. The risk of developing a Bartholin's gland cyst increases with the number of childbirths.

While Bartholin cysts can be quite painful, they are not life-threatening. New cysts cannot absolutely be prevented from forming, but surgical or laser removal of a cyst makes it less likely that a new one will form at the same site. Those with a cyst are more likely than those without a cyst to get one in the future. They can recur every few years or more frequently. Many women who have marsupialization done find that the recurrences may slow, but do not actually stop.

Choledochal cysts are treated by surgical excision of the cyst with the formation of a roux-en-Y anastomosis hepaticojujenostomy/ choledochojujenostomy to the biliary duct.

Future complications include cholangitis and a 2% risk of malignancy, which may develop in any part of the biliary tree. A recent article published in Journal of Surgery suggested that choledochal cysts could also be treated with single-incision laparoscopic hepaticojejunostomy with comparable results and less scarring. In cases of saccular type of cyst, excision and placement of T-shaped tube is done.

Currently, there is no accepted indication for fetal intervention in the management of prenatally suspected choledochal cysts.

Involutional stenosis is probably the most common cause of NLD obstruction in older persons. It affects women twice as frequently as men. Although the inciting event in this process is unknown, clinicopathologic study suggests that compression of the lumen of the NLD is caused by inflammatory infiltrates and edema. This may be the result of an unidentified infection or possibly an autoimmune disease.

The prevalence of salivary stones in the general population is about 1.2% according to post mortem studies, but the prevalence of salivary stones which cause symptoms is about 0.45% in the general population. Sialolithiasis accounts for about 50% of all disease occurring in major salivary glands, and for about 66% of all obstructive salivary gland diseases. Salivary gland stones are twice as common in males as in females. The most common age range in which they occur is between 30 and 60, and they are uncommon in children.

Urethral diverticulum can occur in men, and can cause complications including kidney stones and urinary tract infections.

The duct widening is commonly believed to be a result of secretory stasis, including stagnant colostrum, which also causes periductal inflammation and fibrosis. However, because nonspecific duct widening is common it might be also coincidental finding in many processes.

Smokers seem more often affected by duct ectasia "syndrome" although the reported results are not entirely consistent. The correlation with smoking status appears weaker than for subareolar abscess. Correlation with the actual duct widening is not known.

Both duct widening and duct ectasia syndrome are frequently bilateral, hence systemic causes are likely involved.

Sinus disease often occurs in conjunction with, and in other instances may contribute to the development of NLD obstruction. Patients should be asked about previous sinus surgery, as the NLD is sometimes damaged when the maxillary sinus ostium is being enlarged anteriorly.

Duct ectasia of the breast or mammary duct ectasia or plasma cell mastitis is a condition in which the lactiferous duct becomes blocked or clogged. This is the most common cause of greenish discharge.

Mammary duct ectasia can mimic breast cancer. It is a disorder of peri- or post-menopausal age.

"Duct ectasia syndrome" is a synonym for nonpuerperal mastitis but the term has also been occasionally used to describe special cases of fibrocystic diseases, mastalgia or as a wastebasket definition of benign breast disease.

Correlation of duct widening with the "classical" symptoms of duct ectasia syndrome is unclear. However, duct widening was recently very strongly correlated with noncyclic breast pain.

Duct diameter is naturally variable, subject to hormonal interactions. Duct ectasia syndrome in the classical meaning is associated with additional histological changes.

Sialolithiasis (also termed salivary calculi, or salivary stones), is a condition where a calcified mass or "sialolith" forms within a salivary gland, usually in the duct of the submandibular gland (also termed "Wharton's duct"). Less commonly the parotid gland or rarely the sublingual gland or a minor salivary gland may develop salivary stones.

The usual symptoms are pain and swelling of the affected salivary gland, both of which get worse when salivary flow is stimulated, e.g. with the sight, thought, smell or taste of food, or with hunger or chewing. This is often termed "mealtime syndrome". Inflammation or infection of the gland may develop as a result. Sialolithiasis may also develop because of the presence of existing chronic infection of the glands, dehydration (e.g. use of phenothiazines), Sjögren's syndrome and/or increased local levels of calcium, but in many instances the cause is idiopathic (unknown).

The condition is usually managed by removing the stone, and several different techniques are available. Rarely, removal of the submandibular gland may become necessary in cases of recurrent stone formation. Sialolithiasis is common, accounting for about 50% of all disease occurring in the major salivary glands and causing symptoms in about 0.45% of the general population. Persons aged 30–60 and males are more likely to develop sialolithiasis.

Strictures tend to be diagnosed based on difficulty with insertion and manipulation during sialendoscopy, or by sialography or ultrasound.

A salivary gland fistula (plural "fistulae") is a fistula (i.e. an abnormal, epithelial-lined tract) involving a salivary gland or duct.

Salivary gland fistulae are almost always related to the parotid gland or duct, although the submandibular gland is rarely the origin.

The fistula can communicate with the mouth (usually causing no symptoms), the paranasal sinuses (giving rhinorrhea) or the facial skin (causing saliva to drain onto the skin).

The usual cause is trauma, however salivary fistula can occur as a complication of surgery, or if the duct becomes obstructed with a calculus.

Most parotid fistulae heal by themselves within a few weeks.

The incidence of urethral diverticulum has been increasing in the 2000s, likely due to increasing diagnosis and detection of the condition. It is estimated to be present in as low as 0.02% of all women and as high as 6% of all women, and 40% of women with lower urinary tract symptoms. Most symptomatic urethral diverticula are present in women from 30–60 years old.

84% of periurethral masses are due to urethral diverticula.

Pancreas divisum in individuals with no symptoms does not require treatment. Treatment of those with symptoms varies and has not been well established. A surgeon may attempt a sphincterotomy by cutting the minor papilla to enlarge the opening and allow pancreatic enzymes to flow normally. During surgery, a stent may be inserted into the duct to ensure that the duct will not close causing a blockage. This surgery can cause pancreatitis in patients, or in rare cases, kidney failure and death.

An association with adenoma of the minor papilla has been reported.

Ectopic salivary gland tissue which is located in sites other than the normal location is variously described as aberrant, accessory, ectopic, heterotopic or salivary gland choristoma.

The nasopalatine duct cyst (abbreviated NPDC) occurs in the median of the palate, usually anterior to first molars. It often appears between the roots of the maxillary central incisors. Radiographically, it may often appear as a heart-shaped radiolucency. It is usually asymptomatic, but may sometimes produce an elevation in the anterior portion of the palate. It was first described by Meyer in 1914.

The median palatal cyst has recently been identified as a possible posterior version of the nasopalatine duct cyst.

A Gartner's duct cyst (sometimes incorrectly referred to as "vaginal inclusion cyst") is a benign vaginal cystic lesion that arises from the Gartner's duct, which is a vestigial remnant of the mesonephric duct (wolffian duct) in females. They are typically small asymptomatic cysts that occur along the lateral walls of the vagina, following the course of the duct. They can present in adolescence with painful menstruation (Dysmenorrhea) or difficulty inserting a tampon. They can also enlarge to substantial proportions and be mistaken for urethral diverticulum or other structures.

There is a small association between Gartner's duct cysts and metanephric urinary anomalies, such as ectopic ureter & ipsilateral renal hypoplasia. Because of this, imaging is recommended before excision.

Pancreas or Pancreatic divisum is a congenital anomaly in the anatomy of the ducts of the pancreas in which a single pancreatic duct is not formed, but rather remains as two distinct dorsal and ventral ducts.

Omphalomesenteric duct cysts (ODC, also known as an omphalomesenteric duct remnant or vitelline cyst) are developmental defects relating to the closure of the omphalomesenteric duct. It usually disintegrates within six weeks of gestation, but remnants of the cyst can sometimes be found along the intestines or umbilicus. Any remnants can be removed via surgical means.