Branchial anomalies

1 S T

2 ND

3 R D

4 T H

AS

Branchial Arch Anomalies

Definition

Congenital anomalies of the neck arise as a consequence of disturbances in the complex development of the branchial apparatus of the fetus

Accounts for 17% of the pediatric neck massesClassified according to their branchial cleft or

pouch of origin as well as their anatomic relationships

May take the form of a fistula, sinus or cyst, based on the degree of completion of development of the anomalous structure

Definition

Fistula: represent persistence of both the cleft and the corresponding pouch Lies caudal to the structure derived from that particular arch and

connects the skin to the foregutSinuses:

May be considered partial fistula, usually opening externally, with no internal opening

Fistula and sinuses may be lined by stratified squamous, columnar, or ciliated epithelium, and they may contain lymphoid tissue as well

Cysts: Have neither an internal nor an external opening and are most

often lined by stratified squamous epithelium (ectoderm derived); however, they can be lined by columnar epithelium (endoderm derived from pouches)

1st branchial anomalies

Epidemiology Represent 1% of all branchial anomalies M=F Age cysts (adult > children), fistula and sinuses

(children > adult) Left predominance Cysts > sinuses/fistula 2:1 2 types


Theories/aetiology: Branchial theory Thyropharyngeal duct theory Parotid salivary gland inclusion theory Lymph node epithelial metaplasia theory


Type 1 (1st branchial anomaly) is ectodermally derived and is a duplication of the membranous EAC Contain only epidermoid elements without cartilage or

adenexal structures Runs parallel to the EAC, involving parotid tissue but

usually passing superior to the main trunk of the facial nerve in close proximity

Often begin as fistulous tracts at the pre auricular or pretragal area

May terminate near a bony plate at the level of the mesotympanum

Do not communicate with EAC


Type 2 (1st branchial anomalies) contain both ectoderm and mesoderm More common than type 1 Cyst or external opening is localised in the anterior

neck, always superior to the hyoid bone Tract courses over the angle of the mandible, through

the parotid gland, and terminates near the bony-cartilaginous junction of the EAC

Course of the tract in relation to the facial nerve is variable running either lateral, medial, or even through the main trunk of the nerve



Histopathology Lined with stratified squamous epithelium Histologic architecture may be destroyed by infection Cyst may have lymphoid tissue with germinal centres Ectodermal elements present

Clinical Discharging ear with intact TM Cyst or opening in the pre auricular region Mass in EAC or lower pole of the parotid May present with unilateral facial paralysis 1st branchial anomalies may be assocaited with

hemifacail microsomia


Investigation: Imaging usually not required if uncomplicated

Treatment Surgery after infection resolved superficial

parotidectomy Exploration of facial nerve prior to excision of tract Methylene blue and probe

2nd branchial anomalies

Epidemiology Most common of all branchial anomalies Represent 90-95% of branchial anomalies M = F Mean age of diagnosis 40 y.o 15% < 10 y.o Left predominance 2% bilateral familial clustering Cysts > sinuses/fistula


Type 1: Located along the anterior margin of SCM at the junction of

the middle and lower thirds, deep to the platysma and cervical fascia

Type 2: Lie in contact with the great vessels (most common)

Type 3: Pass medially between the ICA and ECA, extending toward the

lateral pharyngeal wall and lying above the glossopharyngeal and hypoglossal nerves and below the stylohyoid ligament

Type 4: Are very rare and located next to the pharnygeal wall, medial

to the great vessels at the level of the tonsillar fossa


Classified into 4 categories according to anatomical position

Type I-III are most frequent occurring with type II being most common

Bilaterality of second arch anomalies is uncommon (2%)

Tract passes deep to the 2nd arch structure ECA, stylohyoid muscle and posterior belly of

diagatricTract passes superficial to 3rd arch structure

ICA, lateral and above IX and XII


External: anterior border of SCM

Internal: tonsillar fossae Course deep to second

arch structures: external carotid artery,

stylohyoid and posterior belly of digastric

superficial to third arch structures: lateral to CN IX and (XII) internal carotid artery

(courses between carotid vessels)

Cysts commonly in anterior triangle below hyoid


Histopathology: Squamous or respiratory epithelium Lymphoid tissue in the submucosa

Clinical: Cystic lesions are more common than fistulae Smooth, soft masses in the lateral neck and are located

anterior and deep to SCM Fistulae tend to manifest as recurrent neck infections,

often following an URTI, below the level of the digastric muscle

Can present with pain, dyspnoea and dysphagia Associated anomalies of the ossicles, facial nerve and

fallopian canal have also been described

2nd brachial anomalies

Investigation: Radiological

USS +/- FNA CT or MRI

Histopathological FNA show epithelial elements and cholesterol crystals


Treatment: Complete surgical excision after infection resolved Stepladder technique for sinus and fistula Delay until 2-3 years of age Intra-oral approach is possible for isolated pharyngeal

cysts (type IV) Typically addressed via an incision along the anterior

border of SCM

3rd branchial anomalies

Epidemiology Rarely encountered Many authors agree that differentiating between 3rd

and 4th brachial anomalies is difficult on clinical grounds

2-8% of all brachial anomalies slight F>M 97% left sided


Anatomy: Tract is deep to the 3rd arch derivatives and superficial

to structures of the 4th arch Courses posterior to the CCA and or ICA medial to

the ICA and ECA, between the glossopharyngeal and hypoglossal nerves above the superior laryngeal nerve then it medially pierces the posterolateral aspect of the thyrohyoid membrane to open into the pyriform sinus

3rd branchial anomalise

External- as in 2nd BAA Internal: piriform sinus

(superior portion)Course:deep to third arch

structures: CN IX, carotid vessels

superficial to fourth arch structures: superior laryngeal nerve, CN XII,

enter pharynx at thyrohyoid membrane

Cysts in anteroinferior cervical triangle-lower in neck than second branchialcyst


Histopathology As for second arch anomalies

Clinical Complete fistula has a cutaneous opening along the

anterior border of the SCM 3rd branchial anomalies can manifest with upper

airway compromise in the neonate may also manifest with hypoglossal nerve palsy, neck

abscess or retropharyngeal abscess


Investigation: As for 2nd arch anomalies Laryngoscopy look for opening in pyriform sinus Barium swallow looking for tract

Treatment: Piriform sinus needs to be visualised for opening prior

to surgery External approach along the SCM are perferred

4th Branchial anomalies

Epidemiology Extermely rare and, unlike 2nd branchial anomalies,

typically manfest in childhood Only a few cases reported in literature Predominantly left side

4th branchial anomalies

Anatomy: Fistula takes the path of the RLN Begins at piriform fossa exits the larynx near the CT

joint passes between the SLN and RLN Left tract descends alongside the trachea and

oesophagus, through the neck and into the mediastinum to the level of the aorta, looping around ligamentum arteriosum in a posteroanterior direction

Right tract descends lateral to the trachea and oesophagus to the level of the subclavan artery, looping around it in a posterior-anterior direction


Anatomy: Then, on either side, tract ascends in the neck,

posterior to the ICA and CCA pass superior to the hypoglossal nerve exit anterior to the SCM in the lower neck

Clinical: Complete fistula has a cutaneous opening along the

anterior border of the SCM May present with suppuratuve thyroiditis, neck

abscess or retropharyngeal abscess


internal: piriform sinus (inferior portion)

translaryngeal course under thyroid ala, beneath inferior constrictor

exits near cricothyroid joint

superficial to recurrent laryngeal

terminates in anteroinferior region of the neck


Histopathology: As for 2nd arch anomalies

Investigation: As for 3rd arch anomalies

Treatment: Surgical approach is through a traditional thyroid

incision? Because of the rarity of these lesions, there has not

been a standard established for surgical management. Some authors feel that complete exposure of the mediastinal and cervical components is unnecessarily aggressive and likely not indicated

Health & Medicine

Branchial anomalies