branchial anomalies

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  • 1. 1 S T 2 N D 3 R D 4 T H A S Branchial Arch Anomalies

2. 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 masses Classified 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 3. 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 foregut Sinuses: 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) 4. 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 5. 1st branchial anomalies Theories/aetiology: Branchial theory Thyropharyngeal duct theory Parotid salivary gland inclusion theory Lymph node epithelial metaplasia theory 6. 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 7. 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 8. 1st branchial anomalies 9. 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 10. 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 11. 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 12. 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 13. 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 diagatric Tract passes superficial to 3rd arch structure ICA, lateral and above IX and XII 14. 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 15. 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 16. 2nd brachial anomalies Investigation: Radiological USS +/- FNA CT or MRI Histopathological FNA show epithelial elements and cholesterol crystals 17. 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 18. 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 19. 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 20. 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 21. 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 22. 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 23. 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 24. 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 25. 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 26. 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 27. 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


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