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Congenital / metabolic anomalies

Branchial pouch / cleft anomalies

Last author update: 1 August 2015

Last staff update: 15 August 2023

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PubMed Search: Branchial pouch thyroid

See also Lymphoepithelial cyst, Solid cell nests, Cystic ultimobranchial body remnants, Thymic tissue within thyroid gland, Parathyroid tissue within thyroid gland

Table of Contents

Cite this page: Bychkov A. Branchial pouch / cleft anomalies. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/thyroidbranchial.html. Accessed December 26th, 2024.

Definition / general

Congenital lesions due to incomplete obliteration of the branchial apparatus
May be cyst, sinus, fistula or cartilage in anterolateral neck
Cysts derived from branchial cleft have squamous epithelium; cysts derived from branchial pouch have respiratory epithelium, although repeated infections may cause squamous metaplasia (Ann R Coll Surg Engl 2007;89:W12)

Terminology

A sinus is a blind ending tract
"Branchial cleft sinus" connects to the skin, but a "branchial pouch sinus" connects to the pharynx; neither arises from the mesenchyme of the branchial arch (J Laryngol Otol 2004;118:19)
A "true fistula" is a communication between two epithelialized surfaces; a "congenital branchial fistula" should be present at birth and should communicate between a persistent pouch and a cleft
Most of the branchial fistulas are pseudofistulas, formed between a pouch remnant and a skin opening produced following an infection or a surgical incision or are just sinuses (AJNR Am J Neuroradiol 2010;31:755)

Epidemiology

20 - 40 years old, M = F
20% of cervical masses in children (Int J Pediatr Otorhinolaryngol 2011;75:1020)
Cysts: fistulas = 10:1 (Eur J Inflamm 2012;10:39)
2% - 3% are bilateral (Ear Nose Throat J 2008;87:291)

Sites

Sites of cysts:
- First branchial cleft: preauricular area (type I cyst) or below the angle of mandible (type II), may be connected to external auditory canal; cysts are rarely malignant (Diagn Cytopathol 2008;36:876); 5% - 8%
- Second branchial cleft: anterior to sternocleidomastoid muscle in midneck, may communicate with pharynx; 95% (Singapore Med J 2015;56:203)
- Third / fourth branchial cleft (Pyriform sinus fistula): 2% - 5%
  - May be misdiagnosed as bronchogenic cyst
  - Usually left sided and associated with neck infection, treatment is ipsilateral thyroidectomy as lesions pass through thyroid

Pathophysiology / etiology

Branchial theory suggests that incomplete obliteration of branchial cleft mucosa, which remains dormant until stimulated to grow later in life, results in cyst formation (Ascherson, 1832) (Am J Pathol 1967;50:533)
More theories: persistence of vestiges of the precervical sinus, thymopharyngeal duct origin and cystic lymph node origin (J Am Dent Assoc 2003;134:81)

Diagrams / tables

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Branchial apparatus

Branchial cleft anomalies location

Anatomical relations

Clinical features

Slow growing movable mass in the lateral neck, often asymptomatic
Manifested as inflammatory neck mass or fistula
Rarely associated with squamous cell carcinoma (J Laryngol Otol 1994;108:1068), but cystic neck masses should be considered to be nodal metastases until proven otherwise (common sites of small primary occult tumors are tonsil, posterior tonsillar pillar, retromolar tongue, nasopharynx)
Clinical branchial cysts may rarely:
- Arise within thyroid gland (Korean J Radiol 2006;7:149)
- Actually be cystic remnants of ultimobranchial body
- Actually be papillary thyroid carcinoma (Kaohsiung J Med Sci 2007;23:634)
- Arise within ectopic thyroid tissue that transforms to papillary carcinoma (Ear Nose Throat J 2006;85:675, World J Surg Oncol 2006;4:24)
- 33% of patients with congenital third branchial arch anomalies and 45% with fourth branchial arch abnormalities present with acute infectious thyroiditis (Otolaryngol Head Neck Surg 2010;142:21, J Pediatr Surg 2009;44:1432)

Diagnosis

Imaging and fluoroscopic fustulography to visualize cyst / fistula and anatomic tract
Pyriform sinus examination via direct laryngoscopy to detect third / fourth branchial cleft anomaly

Radiology description

Ultrasound: low echogenic lesion with lack of internal septation
CT scan and MRI require sedation in children

Radiology images

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Cystic lesion in left parotid gland

CT fistulogram

Infrahyoid cyst

Prognostic factors

Recurrence rate depends on completeness of resection, mean 5% (Dentomaxillofac Radiol 2012;41:696)

Case reports

18 month old child with third branchial pouch cyst presenting as stridor (Ann R Coll Surg Engl 2007;89:W12)
9 year old boy and 42 year old man with fourth branchial complex anomaly (Case Rep Otolaryngol 2011;2011:958652)
10 year old girl with branchial cleft cyst at an unusual location (Dentomaxillofac Radiol 2012;41:696)
12 year old girl with type II first branchial cleft anomaly presenting as a post auricular salivary fistula (Ann Med Health Sci Res 2014;4:136)
22 year old woman with type I first branchial cleft cyst masquerading as a parotid tumor (Natl J Maxillofac Surg 2014;5:84)
32 year old woman with intrathyroidal branchial cleft cyst (Korean J Radiol 2006;7:149)
50 year old woman with branchial cleft cyst (J Oral Maxillofac Pathol 2014;18:150)
Multiple branchial cleft-like cysts in Hashimoto thyroiditis (Am J Surg Pathol 1989;13:45)

Treatment

Complete surgical excision of cyst and associated tract after clearing infection
Endoscopic cauterization via pyriform sinus for fourth branchial cleft cysts

Clinical images

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Fistula opening (1st branchial cleft anomaly)

First branchial cleft fistula opening

Bilateral fistula opening

Saliva coming out, third branchial fistula

Fistula opening above sternocleidomastoid muscle

Sinus originating from pyriform sinus

With cervical abscess

Fistulous tract in right pyriform sinus

Gross description

A smooth walled cyst with mucoid or watery contents, 2 - 6 cm in diameter (up to 10 cm in greatest dimension)
Infected / ruptured cyst may be obscured or obliterated by the fibroinflammatory reaction; the surrounding soft tissues may be densely fibrotic

Gross images

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Fistula tract

Fistula tract ending in parotid gland

Collaural fistula

Third branchial fistula

Fistula tract exiting pharynx

Fourth branchial fistula

Microscopic (histologic) description

Stratified squamous or ciliated columnar epithelium lining (Am J Pathol 1967;50:765, APMIS 1997;105:623)
Fibrotic wall with lymphoid follicles resembling lymph node or tonsil
May be secondarily infected
Cysts may have sebaceous or mucinous glands
Occasionally found in thyroid tissue as heterotopic cartilage, thymus or solid cell nests representing ultimobranchial body remnants
Parathyroid glands, thymic tissue, tiny masses of cartilage and tiny glands lined by ciliated cells may be seen in normal thyroid glands, presumably related to anomalies of the development of the branchial pouches (J Anat 1976;122:77)

Microscopic (histologic) images

Contributed by Andrey Bychkov, M.D., Ph.D.

PTC: cystic node mimics branchial cyst

Hashimoto thyroiditis with lymphoepithelial cyst

Images hosted on other servers:

Cyst lined by stratified squamous epithelium

Sinus tract in parotid gland

Cyst wall with chronic inflammation

Fibrotic wall of a cyst

Lymphoid aggregates in cyst wall

Ciliated pseudostratified columnar epithelium

Virtual slides

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Case 10, right neck node

Cytology description

Squamous epithelial cells of variable maturity, abundant lymphocytes, macrophages, background of amorphous debris - these features are nonspecific (Acta Dermatovenerol Alp Pannonica Adriat 2006;15:85, Eurocytology)
May be interpreted as suspicious for carcinoma (Cytopathology 2007;18:184)

Cytology images

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Squamous cells, keratin debris

High power

Pap stain

Inflammation

Cholesterol crystals

Videos

Pharyngeal pouches

Differential diagnosis

First branchial cleft cyst: epidermoid cyst, dermoid cyst, cystic sebaceous lymphadenoma
Second branchial cleft cyst: lateral thyroglossal duct cyst
Third branchial cleft cyst: papillary carcinoma with cystic change (positive for TTF1, thyroglobulin)
Fourth branchial cleft cyst: thymic cyst

Additional references

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