Findings - Fistulogram showing fisutla tract extending from skin deep into the neck
Diagnosis - Branchial fistula
Diagnosis - Branchial fistula
The branchial cyst, sinus and fistula are anomalies of the branchial apparatus which consists of five mesodermal arches separated by invagination of ectoderm (clefts) and endoderm (pouch). The branchial fistula is not a true fistula because it rarely has two openings. Even if an internal opening exists, there lies a thin mesodermal tissue between the external and internal opening.
In the embryo, the second arch grows caudally to cover the third and fourth arches and second, third and fourth clefts, eventually fusing with the lower neck. The buried clefts persists as cavities by endoderm and generally disappear with development. If this does not occur, it persists as a branchial cyst. Branchial fistula develops when second arch fails to meet the fifth arch leaving the remnants of second, third and fourth clefts in contact with surface by a narrow canal. A branchial fistula with both external and internal openings develops from a rupture of membrane between the cleft and the pouch at the same time during development.
The branchial cyst is formed from entrapped remnants of either branchial cleft or pouches without complete sinus tracts. The branchial sinus represents a vestigial pouch or cleft, it is a tract with or without a cyst, which has an internal or external opening.
In the embryo, the second arch grows caudally to cover the third and fourth arches and second, third and fourth clefts, eventually fusing with the lower neck. The buried clefts persists as cavities by endoderm and generally disappear with development. If this does not occur, it persists as a branchial cyst. Branchial fistula develops when second arch fails to meet the fifth arch leaving the remnants of second, third and fourth clefts in contact with surface by a narrow canal. A branchial fistula with both external and internal openings develops from a rupture of membrane between the cleft and the pouch at the same time during development.
The branchial cyst is formed from entrapped remnants of either branchial cleft or pouches without complete sinus tracts. The branchial sinus represents a vestigial pouch or cleft, it is a tract with or without a cyst, which has an internal or external opening.
The first branchial arch anomalies are classified by Work (1977) as types I and II.
Type I branchial defects are duplication anomalies of external auditory canal which exists as fistulous tract near the lower portion of parotid gland in close association with the facial nerve. They present as sinus tracts near the postauricular sulcus or choncha or anterior to the tragus. These anomalies course through the infratemporal fossa parallel to EAC and may end either in the EAC or middle ear space.
Type II defect is less common and presents as a cyst or sinus in the anterior triangle of neck below the angle of mandible. These anomalies course superiorly and posteriorly through the parotid gland in close proximity of facial nerve and terminate laterally in the region of bony cartilaginous junction of EAC.
Second branchial anomalies present along the anterior border of sternocleidomastoid in its lower third. A tract commonly extends into the pharynx entering anywhere from nasopharynx to hypopharynx but most commonly in the region of tonsillar fossa. The tract usually passes between the second and third arch structures, i.e. it passes medially between the internal and external carotid arteries above the glossopharyngeal nerve and below the stylohyoid ligament.
Third branchial anomalies present along the anterior border of the sternocleidomastoid muscle in the lower third of the neck. The tract passes behind the internal and external carotid arteries and the glossopharyngeal nerve and while crossing over the hypoglossal and superior laryngeal nerves. It enters the pharynx at the level of the pyriform fossa.
Fourth branchial anomalies are theoretically possible. These anomalies present as sinus tracts in the anterior triangle in a fashion similar to that of second and third branchial anomalies. If they exist their tract passes below the arteries of the fourth arches into the mediastinum and there continues superiorly along the ascending portion of recurrent laryngeal nerve to enter the upper part of oesophagus.
Type I branchial defects are duplication anomalies of external auditory canal which exists as fistulous tract near the lower portion of parotid gland in close association with the facial nerve. They present as sinus tracts near the postauricular sulcus or choncha or anterior to the tragus. These anomalies course through the infratemporal fossa parallel to EAC and may end either in the EAC or middle ear space.
Type II defect is less common and presents as a cyst or sinus in the anterior triangle of neck below the angle of mandible. These anomalies course superiorly and posteriorly through the parotid gland in close proximity of facial nerve and terminate laterally in the region of bony cartilaginous junction of EAC.
Second branchial anomalies present along the anterior border of sternocleidomastoid in its lower third. A tract commonly extends into the pharynx entering anywhere from nasopharynx to hypopharynx but most commonly in the region of tonsillar fossa. The tract usually passes between the second and third arch structures, i.e. it passes medially between the internal and external carotid arteries above the glossopharyngeal nerve and below the stylohyoid ligament.
Third branchial anomalies present along the anterior border of the sternocleidomastoid muscle in the lower third of the neck. The tract passes behind the internal and external carotid arteries and the glossopharyngeal nerve and while crossing over the hypoglossal and superior laryngeal nerves. It enters the pharynx at the level of the pyriform fossa.
Fourth branchial anomalies are theoretically possible. These anomalies present as sinus tracts in the anterior triangle in a fashion similar to that of second and third branchial anomalies. If they exist their tract passes below the arteries of the fourth arches into the mediastinum and there continues superiorly along the ascending portion of recurrent laryngeal nerve to enter the upper part of oesophagus.