Pictoral Essay: Congenital Anomalies of the Branchial Apparatus

Authors Institutions

Objectives:

    Understand Embryology of the branchial apparatus and embryogenesis of its anomalies.

Understand various classifications of branchial anomalies. Recognize and interpret imaging findings associated with anomalies of the branchial apparatus.

Direct workup using various imaging modalities used in evaluation of branchial anomalies.

Embryology of Branchial Apparatus

    

4 th

week of gestation.

Six mesodermal arches

Branchial clefts – ectodermally lined.

Pharygeal pouches – endodermally lined.

CN and Aortic arch

accompany each branchial arch.

Branchial Apparatus

Development of Branchial Apparatus

   

1 st Arch, Cleft, and

Pouch persist.

2 nd Arch increases in thickness and proliferates caudally

2 nd , 3

His.

rd , and 4 th Cleft form cervical sinus of

Sinus of His lined by ectoderm.

Further Differentiation

  

1 st Branchial cleft

becomes external auditory canal

Cervical Sinus of His obliterated Pharyngeal pouches

develop into thymus, parathyroid glands, and ultimobranchial body, then migrate to their final position.

Branchial Derivatives

Embryogenesis

 Vestigial remnants – resulting from incomplete or failed obliteration of branchial apparatus.

 Buried cell rests – cells are trapped in branchial apparatus and form branchial cleft cysts later in life.

Branchial Anomalies



Sinus

– incomplete tract, opens externally 

Fistula

– communicated both externally and internally from persistence of both cleft and pouch.



Cyst

– no internal or external comunication.

Radiographic Evaluation

   Begins with Ultrasound    Non ionizing, non invasive.

Determines cystic vs. solid; size, and extent.

Color doppler – vascularity.

CT

 Morphologic characterization and staging.

  Bone structures, calcifications, deep soft tissue anatomy Low dose neck CT to avoid excess radiation.

MRI

 Multiplanar capability    Absence of ionizing radiation.

Superior contrast resolution and anatomic characterization of soft tissues.

Often requires sedation.

First Branchial Anomalies

     5-8 % of all defects.

Middle aged women.

1 st

Branchial structures: maxilla, mandible, eustacian tube, external auditory canal, middle ear structures.

Completed by 6-7 wks.

Can insinuate within Parotid gland.

10 year old female presenting with fistula.

Second Brancial Apparatus Anomalies

     Vast majority (>95%) of branchial anomalies.

¾ of anomalies are cysts. Fistulas and sinuses present earlier.

Passes between internal

and external carotid

arteries and ends near tonsillar fossa.

External communication with cervical sinus of His.

Four types of 2

nd

BCC

    Bailey type I:   most superficial Anterior surface SCM

Bailey type II:

 Classic location

Bailey type III:

 Extends medially between ICA and ECA bifurcation

Bailey type IV:

 Lies in pharyngeal mucosal space.

41 year old male with neck mass.

  Bailey type II:  most common.

 Remnant of cervical sinus of His.

Classic location:  Anterior to SCM   Lateral to carotid space Posterior to submandibular gland.

10 mo. Child presented with neck mass. Suspected abscess.

Third Branchial Apparatus Anomalies.

       Very rare.

Requires careful anatomic examination.

Pierces the thyrohyoid membrane and enters pyriform sinus Posterior to carotid vessels

Anterior to Vegus nerve.

Posterior compartment

behind SCM. Joins Cervical Sinus of His.

Child with Neck Fullness.

 Cystic mass in left posterior compartment  Beneath SCM.



Posterior to Carotid vessels.

Fourth Branchial Apparatus Anomalies.

      Very rare: complete fistula not reported.

Origin at apex of pyriform sinus, penetrates thyrohyoid membrane. Descends below aortic arch

Inferior to superior lanryngeal nerve.

Superior to recurrent

laryngeal nerve.

Cervical sinus of His.

3 yo with recurrent neck abscess.

   Infected cyst anterior to carotid

artery

May communicate with pyriform sinus or cervical sinus of His Track descends below aortic arch.

Case 1: Child with right facial mass.

Submandibular Gland Carotid Sheath Sternocleidomastoid

Case 2: Child with purulent drainage from EAC.

Case 3: Child presenting with neck mass.

Review

    Defects in branchial apparatus include

branchial, thymic, and parathyroid

anomalies.

Manifest as cysts, sinuses, fistulas, and

ectopic glands.

Embryogenesis: vestigial remnants from incomplete obliteration or buried cell rests.

Radiography, US, CT, MRI used for evaluation

Review

     Branchial Cleft Anomalies: Fistulae, cysts, sinuses.

Four types: Type II Branchial Cleft Cysts most common.

Classic location BCC II: anterio-medial to SCM, displacing submandibular glands anteriorly, lateral to carotid vessels.

Types II – IV merge externally as Cervical sinus of His.

Types III and IV are rare and require careful anatomic examination for differentiation.

References

1. Benson MT, Dalen K, Mancuso AA, et al.: Congenital abnormalities of the branchial apparatus: embryology and pathologic anatomy. Radiographics 12:739-748, 1992.

2. Meuwly JY, Lepori D, Theumann N, et al.: Multimodality Imaging Evaluation of the Pediatric Neck: Techniques and Spectrum of Findings. Radiographics 25:931-948, 2005.

3. Koeller K, Alamo L, Adair C, Smirniotopoulos J.: Congenital Cystic Masses of the Neck: Radiologic-Pathologic Correlation. Radiographics 19:121-146, 1999.

4. Langman J. Medical Embryology 3 rd Ed. Baltimore: Williams & Wilkins, 1975; 234-236.

5. Barry H. The aortic arch derivatives in the human adult. Anat Rec 1951; 111:221-238.