slideshow of pharyngeal arches and its development and various anomalies assosciated with it and its its classification and management.

1. PHARYNGEAL ARCHES AND
ITS ANOMALY
DR. AYUSHREE
DR N.K. SINGH SIR UNIT
( ENT-IIB)

2. PHARYNGEAL ARCHES
•Pharyngeal arches are also known as branchial arches because of their evolutionary
origin supporting the gills in the earliest vertebrates. Many of the changes seen during
development of the mammalian pharynx reflect the functional evolutionary origins of
this region.
•As successive populations of neural crest cells migrate around the pharynx at
progressively more caudal levels, five pairs of pharyngeal arches are formed. This
process is complete by stages 14–15 (5 weeks).
•Pharyngeal clefts (grooves) separate the arches externally; they are matched internally
by internal depressions, the pharyngeal pouches.
•Each pharyngeal arch consists of epithelial covering, ectoderm externally and endoderm
internally and endoderm internally, filled with mesenchyme that is mainly of neural
crest origin, with a contribution from primitive streak derived mesenchyme (paraxial
mesenchyme).
•The neural crest cells of each arch form a skeletal element and associated connective

8. 1ST BRANCHIAL CLEFT SINUS ( <10%)
-The external opening in the neck varies in position but
lies on a line between the tragus and the hyoid bone. The
opening is often inconspicuous and appears as a skin-
lined pit.
-The superior attachment of the sinus is variable: there
may be an opening anterior to the tragus or the tract may
form a true fistula running inferior to the floor of the EAC
and opening at the osseocartilaginous junction in the
external auditory meatus or rarely forming a frenulum-
like band between the floor of the meatus and the umbo

9. Histology
The sinus (sometimes known as a
collaural fistula) is usually a sizeable
tract, often formed of cartilage, and lined
with squamous epithelium.
The original classification by Work and
Work2 divides them into two types
according to the presence or absence of
mesothelial elements within the wall.
• Type I lesions are of ectodermal origin
and are present medial to the concha.
They are usually superficial and simple in
nature.
• Type II lesions are both ectodermal and
mesodermal in origin and contain cartilage
and hair follicles. The more inferior
opening of the type II fistula is usually
below the angle of the mandible and the
tract is intimately related to the facial
nerve trunk.

10. PRESENTATION :
The opening is present at birth and may become more obvious by the discharge
of epithelial or sebaceous debris. The sinus may become acutely infected and
may progress to abscess formation. Being lined with skin, these lesions do not
discharge mucus.
INVESTIGATION :
Cross-sectional imaging will usually show the tract, which is often substantial in
calibre but will not clearly demonstrate its relationship to the facial nerve. MRI is
preferable over CT but still one can go multi slice helical CT.
TREATMENT :
INDICATION :Surgical excision of these lesions is usually advocated if at all
symptomatic or if one or more episodes of infection have already occurred.
CONTRAINDICATION :Surgery is ill-advised during acute infection and a period of
quiescence should be awaited followed by elective excision

11. 1. A parotidectomy-type incision is modified to include the lower opening of the
sinus. The sinus tract at this point can be followed for a small distance upwards;
when its nature and direction are confirmed.
2. The facial nerve trunk must be identified as it leaves the skull base and enters
the parotid gland. The mandibular branch in particular should be followed so
that it can be preserved while freeing the tract. Sharp dissection will often be
required to free the nerve from the tract, particularly if multiple infections have
ensued or previous attempts at incision and drainage have been made. In most
instances the lesion will run deep to the branches of the facial nerve, which may
be adherent if there has been recurrent infection, though the relationship is
unpredictable.
3. The superior part of the sinus tract also has an unpredictable relationship to
the cartilages of the external auditory canal (EAC). It may terminate at the canal

12. 4. The lesion does not extend medial to the cartilaginous canal but a
strand may cross the lumen of the canal from the osseocartilaginous
junction to be attached to the umbo. Facial nerve exposure and
protection is required in nearly every case of first branchial cleft sinus. If
this is done, then risk to the facial nerve is minimized.
5. The upper end of the lesion must be followed and excised to ensure
that no squamous epithelium remains, and this may require opening of
the EAC and use of the otological microscope and ear instruments.
6. Closure of the wound with suction drainage and, if necessary, light
packing of the ear canal completes the operation

13. SECOND BRANCHIAL CLEFT SINUSES (90%)The second branchial arch forms the epidermis of the upper neck and dorsal pinna.
The mesoderm forms the facial muscles and the body of the hyoid, and the
endodermal elements form the root of the tongue, the foramen caecum, the thyroid
stalk and the tonsil.
The second branchial cleft sits immediately caudal to these structures and it is
persistence of this cleft that leads to the formation of the second branchial arch
sinus.
Second branchial arch sinuses may be associated with branchio-oto-renal
syndrome, especially if bilateral.
 The second branchial cleft sinus presents as a congenital opening on the lower
neck, anterior to the sternocleidomastoid muscle.
 The tract of the second branchial cleft sinus is directed proximally and medially to
pass between the internal and external carotid arteries.
The proximal end may communicate with the pharynx through the palatine tonsil to
form a true fistula in some cases, although most lesions are not patent through their
whole length.
The sinus nearly always leaks clear or mucoid fluid from the distal external opening
due to secretions from ectopic salivary tissue in the wall of the sinus itself rather than
any leakage from the pharynx.

14. BAILEYS CLASSIFICATION :
• Type I: deep to platysma, anterior to sternocleidomastoid
• Type II: abutting internal carotid artery and adherent to internal jugular
vein (most common)
• Type III: extending between internal and external carotid arteries
• Type IV: abutting pharyngeal wall and potentially extending superiorly
to skull base

17. INVESTIGATION :
• As a rule with second branchial cleft sinuses, the diagnosis is evident and
no further investigation is required.
• Neck ultrasonography can characterize the size of tract or associated
sharply demarcated cyst, and renal tracts can be imaged to exclude
horseshoe or duplex kidney.
• However, a radiopaque sinogram is not routinely indicated.
• Cross-sectional imaging will usually show the close relations of a second
branchial cyst and is particularly helpful for type III or IV presentations.
• MRI is preferable to CT in children to minimize exposure.

18. TREATMENT :
•Because of the risk of infection, excision of second branchial cleft sinuses is
advisable.
•Surgery can be performed at any age and aims to excise the tract completely
when no infection is present. A fusiform skin incision is made around the
external opening and the tract can be followed upwards with microbipolar
dissection and counter traction with lacrimal retractors.
• If the distance between the external opening and pharynx is too great to allow
good access, a second stepladder incision is made superiorly in the neck to
enable the cranial portion of the tract to be visualized and excised.
•The tract will be seen to enter the pharyngeal muscle at the level of the palatine
tonsil and can be ligated and excised at this level.
•Although ipsilateral tonsillectomy is unnecessary in the vast majority of cases,
tonsillectomy should be considered in the larger type IV second branchial cleft
cyst that abuts the pharynx . Care must be taken to avoid the hypoglossal nerve
in the superior part of the dissection. Complete excision of the sinus should
prevent recurrence.

19. THIRD & FOURTH PHARYNGEAL
POUCHES SINUS (1-2%)
•Third and fourth pharyngeal pouch sinuses are rare abnormalities, accounting for 1–
2% of branchial lesions, which can present as a sinus, cyst, thyroid gland abscess or
even a fistula from pharynx to skin.
• They almost always occur on the left side.
•They tend to present in early childhood with associated infections or in neonates
with airway obstruction.
•The third and fourth branchial arches are related to the thyroid, parathyroid and
thymus and therefore tracts may course close to or through these structures: both
originate at the pyriform sinus.
•The third arch is associated with the glossopharyngeal nerve whereas the fourth is
related to the superior laryngeal branch of the vagus nerve. This can explain the
theoretical course of third and fourth pharyngeal pouch anomalies, however case
reports to demonstrate these are lacking.

20. 3rd pharyngeal pouch presenting
as a cystic swelling on left side
of hyoid bone
4TH pharyngeal pouch presenting as a
draining neck wound on the anterior
portion of the patient’s left
sternocleidomastoid muscle.

21. PRESENTATION :
•These anomalies present most commonly with some form of infection, often
recurrent thyroid abscess, which is treated with incision and drainage without
recognition of the diagnosis and rendering recurrence inevitable.
INVESTIGATION :
•Various investigations have been proposed: barium swallow, radioiodine scan,
ultrasonography and CT.
•However, MR imaging alone is suitable followed by rigid endoscopy under
anaesthesia to identify an opening in the pyriform sinus.
TREATMENT :
•Although wide-field extirpation of the cyst, tract and ipsilateral thyroid lobe
using a hybrid open and endoscopic approach to the pyriform sinus was the
standard treatment, modern management utilizes endoscopic cautery of the
pyriform fossa sinus alone as first-line treatment.
•Bailey described successful endoscopic diathermy of the pyriform fossa opening
in two cases in 2004 which has become first-line treatment to obliterate the
tract and avoid recurrent infection.
•Garabedian recognized a higher recurrence rate in neonates in a series of
20 children and recommended resection via open approach rather than

22. TREATMENT :
•If the sinus or cyst is symptomatic, local excision is the treatment of
choice.
•The sinus is explored under general anaesthetic with a lacrimal probe
which usually shows deep extension towards the roof of the ear canal
for 10 mm or more.
•The punctum is excised with a fusiform skin paddle and excised in
continuity with the entire tract, which is usually adjacent to the
underlying cartilage; excising a portion of this reduces the risk of
recurrence.
• Some will use methylene blue to guide dissection but others avoid this
in case of spillage into the field, which makes dissection more awkward.

23. THYROGLOSSAL DUCT CYST
•Thyroglossal duct cysts are the most common congenital abnormality in the head
and neck region.
•The thyroid develops from the foramen caecum, which lies in the midline of the
tongue at the junction of the anterior two-thirds and posterior one-third.
•In normal development, the thyroid descends through the tongue, passing
caudally with an intimate relationship to the hyoid bone and finishing in the
anterior neck overlying the trachea and laryngeal cartilage.
•In around one-third of cases the duct has been found posterior to the hyoid bone,
which has important implications in surgical treatment. The duct may fail to
involute during the weeks 8–10 of gestation and as a result an abnormal cyst may
arise anywhere along the tract and may contain thyroid tissue.

24. PRESENTATION
•Despite being a congenital lesion, thyroglossal duct cysts
often present later in childhood or early adulthood. The
complaint is usually of a midline swelling in the neck although
it can occur laterally, usually left sided in around 10% of cases.
•The mass elevates on swallowing and tongue protrusion. It
may present with a complication of infection or fistula
formation to the skin if surgically drained.
INVESTIGATION
•It is possible for the thyroglossal cyst to contain the only
functioning thyroid tissue and therefore removal would result
in hypothyroidism. Ultrasound is useful in confirming the
diagnosis and the presence of a normal thyroid gland in the
usual position.
•Cross-sectional imaging before revision surgery is advised to

25. TREATMENT
•It is nearly always surgical excision unless the cyst is very small and
asymptomatic.
•If a fistula to the skin is present, this is excised with the underling cyst and tract.
•The definitive operation is that described by Sistrunk from the Mayo Clinic in
1920,9 removing with the thyroglossal duct a portion of the hyoid bone, a
portion of the raphe joining the mylohyoid muscles, a portion of each
genioglossus muscle and the foramen caecum.
•If the surgery is performed as he described, recurrence rates can be kept below
5%; this was confirmed in a 2013 systematic review including 750 patients
having primary surgery. Problems arise where there has been a deviation from
Sistrunk’s procedure resulting in an incomplete resection. Recurrence rates
following incomplete excision rise to 27%.
•The operation has been developed further with an extended or modified
Sistrunk procedure, which involves a wider block dissection incorporating the
infrahyoid region to the thyroid isthmus initially used for recurrent disease but
now applied to all patients to minimize complications.

26. LINGUAL THYROID
Lingual thyroid is the result of failure of descent of the thyroid anlage from the foramen caecum of the tongue.
It is a rare entity with prevalence of 1 : 100 000.
Girls are more commonly affected.12 In 70–80% of these cases, the lingual thyroid is the only thyroid tissue
present.
Up to one-third have hypothyroidism.
Malignancy has been reported and seems to carry the same risk as thyroid in a normal cervical location.
PRESENTATION
Depending on size, lingual thyroid can present with dysphagia, airway obstruction, haemorrhage or endocrine
dysfunction.
More often the patient is completely asymptomatic with suspicion only after other investigations, following
routine ENT examination or detected on parental curiosity.
INVESTIGATIONS
Imaging will confirm lingual thyroid with either CT or MRI.
Although MRI is preferred to avoid ionizing radiation. In addition to the lingual thyroid, imaging is used to identify
if there is thyroid tissue in the normal cervical location.
Ectopic thyroid has been reported in the oropharynx, larynx, infrahyoid neck, mediastinum, oesophagus and
heart.
Technetium (99mTc) thyroid scan will identify metabolically active thyroid tissue in the tongue base and no uptake
in the neck.

28. TREATMENT
•For small, asymptomatic lingual thyroids, suppression with TSH may
be effective in checking growth.
•Reduction is often slow and dramatic results should not be expected.
Paediatric endocrinology input is essential.
•Use of radioactive iodine for thyroid ablation is generally avoided in
children. Surgical excision is occasionally required when significant
obstructive symptoms are present or repeated or severe haemorrhage
is an issue.
•Transoral resection is usually possible using nasotracheal intubation.
• For larger and deeper lesions, an external approach may be required.
This may even necessitate planned tracheostomy for large masses
where swelling and obstruction are inevitable.
•Lifelong monitoring of thyroid function is essential.

29. CONGENITAL MIDLINE CERVICAL CORD
AND CLEFTEMBRYOLOGY
Congenital midline cervical cord/cleft (CMCC) is a rare congenital abnormality forming on the anterior neck
which may extend to the mediastinum.
It was first described by Bailey in 1924.
AETIOLOGY :
It is unclear but it is felt to arise due to failed midline fusion of the second and third branchial arches.
PRESENTATION :
CMCC may present at birth with a cleft extending from the mentum to the sternum. There may be no
external defect seen but a characteristic ‘cord’ seen or palpated below the skin when the neck is extended.
If a cleft is present, serous discharge may be evident and the upper end will have a pseudonipple
appearance.
IMAGING
CT or MRI allows characterization of the location and depth of the tract and differentiation from other
midline congenital lesions.
TREATMENT
If there is no skin breakdown and the patient is asymptomatic, a conservative approach may be adopted.
Surgery is indicated for cosmetic reasons and prevention of cervical contractures. Elective surgical excision

31. SINUS STERNOCLAVICULARIS
PRESENTATION
Sinus sternoclavicularis is usually present at birth with an asymptomatic sinus at or
near the sternoclavicular joint, more often on the left side.
IMAGING
Ultrasound allows characterization of the location and depth of the tract and
confirmation of normal thyroid gland. Often no further imaging is required.
TREATMENT
If there is no skin breakdown and the patient is asymptomatic, a conservative approach
may be adopted. Elective surgery is indicated for cosmetic reasons, usually involving
excision of a blind-ending sinus which peters out adjacent to the sternoclavicular joint.

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