Branchial Cleft Cyst

 Enlarges after upper respiratory tract infection



• Along anterior border of sternocleidomastoid muscle

• Initial work-up of suspected branchial cleft anomaly (in order)
image Intravenous or oral antibiotics (if infected), FNA, endoscopy &/or radiographic studies, surgery

• Complete surgical excision yields low recurrence risk




Microscopic




• Cyst lined by various types of epithelium (90% stratified squamous)
image Basement membrane often beneath epithelium

• Lymphoid aggregates in cyst wall

• Lumen is filled with keratinaceous debris in many cases


Ancillary Tests




• p16 may show focal, strong staining of superficial squamous epithelium and interdigitating cells


Top Differential Diagnoses




• Metastatic cystic squamous cell carcinoma, bronchiogenic cyst, cervical thymic cyst, metastatic cystic thyroid papillary carcinoma, thyroglossal duct cyst, dermoid cyst, laryngocele

image
CT of 2nd Branchial Cleft Cyst
Axial contrast-enhanced CT reveals a 2nd branchial cleft cyst (BCC) image located posterior to the submandibular gland image, lateral to the carotid space image, and anterior to the sternomastoid muscle image. Capsule thickening suggests inflammation.


image
Gross Photo of Branchial Cleft Cyst
The resection specimen includes a benign lymph node image, separate from the cyst immediately below. Note the thick, fibrous connective tissue wall image surrounding the cyst, filled with hemorrhagic and keratinaceous material.

image
Keratinaceous Debris in Branchial Cleft Cyst
The lumen of this BCC is filled with keratinaceous debris. There is a thin, squamous epithelium image without any atypia. There is a germinal center image within the associated lymphoid tissue.

image
Metaplastic Squamous-Lined Cyst
The cyst is lined by metaplastic squamous epithelium subtended by a very thin basement membrane between the epithelium and lymphoid tissue. Metaplasia is usually seen in patients who have had previous infection.


TERMINOLOGY


Abbreviations




• Branchial cleft cyst (BCC)


Synonyms




• Lateral neck cyst

• Cervical lymphoepithelial cyst


Definitions




• By convention, BCC refers to congenital developmental lateral cervical cyst derived from remnants of 2nd branchial apparatus
image ~ 80-90% of all branchial anomalies arise from 2nd branchial apparatus

image Encompasses branchial cyst, sinus, or fistula


ETIOLOGY/PATHOGENESIS


Branchial Apparatus




• Precursor of many head and neck structures
• 2nd branchial arch overgrows 2nd, 3rd, and 4th clefts, forming “cervical sinus”

• Embryogenesis usually complete by 6-7 weeks of gestation

• Failure of obliteration of cervical sinus results in 2nd branchial cleft remnant (cyst, sinus, or fistula)

image Sinus is respiratory epithelium lined, but squamous metaplasia and lymphoid hyperplasia develop as consequence of immunologic stimulation during infection

• 2nd branchial cleft fistula extends from skin anterior to sternocleidomastoid muscle (SCM), through carotid artery bifurcation to terminate in tonsillar fossa

• 3rd and 4th BCCs are very uncommon (< 5%)
image Recurrent neck abscess or acute suppurative thyroiditis

image Vast majority on left side (90-95%)

• Some authors posit cystic transformation of cervical lymph nodes (specifically in adults)


CLINICAL ISSUES


Epidemiology




• Incidence
image Uncommon

– Still, BCC are 1 of most commonly encountered congenital anomalies in pediatric otolaryngic practice

– Thyroglossal duct cysts are most common

image BCC accounts for ~ 20% of all congenital cervical cysts

– Cysts > > sinuses (3:1)

image ~ 80-90% of all branchial cleft anomalies are 2nd BCCs

image 4th branchial cleft anomalies are rare and involve larynx (neonatal stridor and recurrent deep neck infection)

• Age
image Bimodal presentation
– < 5 years old (24%)

– 20-40 years old (75%)

– ~ 1% in > 50 years

• Sex
image Equal gender distribution


Site




• Lateral neck near mandibular angle
• Along anterior border of SCM

image Anywhere from hyoid bone to suprasternal notch

• Curiously, left-sided predominance for 4th branchial anomalies (> 90%)


Presentation




• Painless cervical swelling
image Along anterior border of SCM

image Often present for long duration

image May be painful (if infected)

• Waxing and waning lesion
image Frequently enlarges in concert with upper respiratory tract infection

image Patients present during phase of recent enlargement

image May lie dormant (clinically silent) for years

• Compressible, fluctuant

• Mucoid or pus-like secretions from sinus tract skin opening (when opening is present)
image Patients present with external fistulae ± internal opening

• Clinically, some lesions may mimic parotid mass or odontogenic infection

• Bilateral lesions are usually identified in syndromic or familial association

• Clinically, 1st or 4th BCC more likely to have incision and drainage procedures, resulting in recurrence

• Important: Must consider metastatic cystic squamous cell carcinoma (SCC) in adults


Endoscopic Findings




• Advocated as part of initial assessment of neck cyst
image Assess internal opening or draining sinus/fistula


Natural History




• Repeated infections and inflammation


Treatment




• Options, risks, complications
image Initial work-up of suspected branchial cleft anomaly (in order)

– Intravenous or oral antibiotics (if infected)

– Fine-needle aspiration

– Endoscopy (concurrent with surgery in some cases)

– Radiographic studies

– Surgery in nonresolving cases

image Avoid repeated incision and drainage, as it yields high recurrence rate

image Noninfected lesions are more easily removed than infected lesions

image Entire fistula tract must be removed to prevent recurrence

image Complications include possible wound infection and cranial nerve paresis

• Surgical approaches
image Combined simultaneous endoscopic identification of sinus tract with lateral external cervical dissection
– Cauterization of fistula used by some practitioners

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Branchial Cleft Cyst

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