branchial anomalies
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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
1st branchial anomalies
Theories/aetiology: Branchial theory Thyropharyngeal duct theory Parotid salivary gland inclusion theory Lymph node epithelial metaplasia theory
1st branchial anomalies
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
1st branchial anomalies
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
1st branchial anomalies
1st branchial anomalies
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
1st branchial anomalies
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
2nd branchial anomalies
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
2nd branchial anomalies
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
2nd branchial anomalies
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
2nd branchial anomalies
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
2nd branchial anomalies
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
3rd branchial anomalies
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
3rd branchial anomalies
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
3rd branchial anomalies
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
4th branchial anomalies
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
4th branchial anomalies
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
4th branchial anomalies
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