Branchial Cleft Cysts

1
Branchial Cleft Cysts
David M. Chaky, MD

• Dept. of Radiology, UNC Chapel Hill

2
Introduction

• The embryologic model is used to explain the
  origins of all branchial apparatus anomalies.
• The most accepted theory proposes that vestigial
  remnants result from incomplete obliteration of
  the branchial apparatus or buried cell rests,
  and, thus, if cells are trapped  in the branchial
  apparatus during  the embryologic stage, they
  can  form branchial cysts later in life.

3

• The branchial apparatus consists of a series
  of  6 mesodermal arches separated from each other
  externally by ectodermal-lined branchial clefts
  (grooves) and internally by endodermal- lined
  pharyngeal pouches.
• By the end of the 4th week of gestation, 4 well-de
  fined pairs of branchial arches are visible
  externally the 5th and 6th arches are small and
  cannot be seen on the embryonic surface.

4
Embryology and Anatomy

• Branchial System 6 pairs of pharyngeal arches
  separated by endodermally lined pouches and
  ectodermally lined clefts.
• Each arch consists of a nerve, artery, and
  cartilaginous structures.
• The remaining neck musculature gains
  contributions from cervical somites.

5
Common Lateral Neck Masses in Infancy

• Branchial cleft anomalies
• Laryngoceles
• Dermoid and Teratoid Cysts
• Sternocleidomastoid Pseudotumor of Infancy
  (fibromatosis colli)
• Plunging ranulas
• Adenopathy

6
First Branchial Cleft Cysts

• Imaging Findings
• Best diagnostic clue Cystic mass around pinna
  and EAC (type I) or extending from EAC to angle
  of mandible (type II)
• Well-circumscribed, non enhancing or
  rim-enhancing, low-density mass
• If infected, may have thick enhancing rim or be
  dense internally
• Top Differential Diagnoses
• Benign Lymphoepithelial Cysts
• Venolymphatic Malformation (VLM)
• Suppurative Adenopathy/Abscess
• Nontuberculous Mycobacterial Adenitis

7
First Branchial Cleft Cysts

• Type I
• Ectodermal Duplication anomaly of the EAC with
  squamous epithelium only.
• Parallel to the EAC
• Pretragal, post auricular
• Connection with TM or MalleusgtIncus
• Surgical Excision

8
First Branchial Cleft Cysts

• Type II
• Squamous epithelium and other ectodermal
  components
• Anterior neck, superior to hyoid bone.
• Courses over the mandible and through the parotid
  in variable position to the Facial Nerve.
• Terminates near the EAC bony-cartilaginous
  junction.
• Surgical excision- superficial parotidectomy

9
First Branchial Cleft Cyst, Type 2
10
First Branchial Cleft Cysts

• Accounts for 8 of all branchial apparatus
  remnants
• Most common location for 1st BCC to terminate is
  in EAC between its cartilaginous bony portions

11
Second Branchial Cleft Cysts

• Most Common (90) branchial anomaly
• Painless, fluctuant mass in anterior triangle
• Inferior-middle 2/3 junction of SCM, deep to
  platysma, lateral to IX, X, XII, between the
  internal and external carotid and terminate in
  the tonsillar fossa
• Surgical treatment may include tonsillectomy

12
Second Branchial Cleft Cysts

• Imaging Findings
• Low density cyst with non enhancing wall
  surrounding soft tissues, unless infected
• If infected, wall is thicker enhances with
  surrounding soft tissues appearing "dirty"
  (cellulitis) or internally dense
• Top Differential Diagnoses
• Lymphangioma
• Thymic cyst
• Suppurative jugulodigastic node
• Cystic vagal schwannoma
• Cystic malignant adenopathy (ALWAYS CONSIDER THIS
  POSSIBILITY IN ADULTS!)

13
Second Branchial Cleft Cysts
14
Second Branchial Cleft Cysts

• Epidemiology 2nd BCC account for gt 90 of all
  branchial cleft anomalies in teens and adults,
  66-75 in children
• Most common signs/symptoms Painless,
  compressible lateral neck mass in child or young
  adult
• Neck mass often chronic, recurrent, increasing
  in size with upper respiratory tract infection
• Beware an adult with first presentation of "2nd
  BCC
• Mass may be metastatic node from head neck
  SCCa primary tumor

15
Third Branchial Cleft Cysts

• Rare (lt2)
• Similar external presentation to 2nd BCC
• Internal opening is at the pyriform sinus, then
  courses cephalad to the superior laryngeal nerve
  through the thyrohyoid membrane, medial to IX,
  lateral to X, XII, posterior to internal carotid
• Surgical approach must visualize recurrent
  layngeal nerves- Thyroidectomy incision

16
Third Branchial Cleft Cysts
17
Third Branchial Cleft Cysts
Imaging Findings Best diagnostic clue
Unilocular thin-walled cyst in posterior cervical
space (posterior triangle) May occur anywhere
along course of 3rd branchial cleft or pouch Top
Differential Diagnoses 2nd branchial cleft
cyst 4th branchial cyst Lymphangioma
Infrahyoid thyroglossal duct cyst Suppurative
adenopathy External laryngocele
Cystic-necrotic lymph node
18
Fourth Branchial Cleft Cysts

• Courses from pyriform sinus apex caudal to
  superior laryngeal nerve, to emerge near the
  cricothryoid joint, and descend superficial to
  the recurrent laryngeal nerve.

19
Fourth Branchial Cleft Cysts
20
Fourth Branchial Cleft Cysts
Imaging Findings Best diagnostic clue
Unilocular thin-walled cyst in superior lateral
aspect of LEFT thyroid lobe with associated
thyroiditis May occur anywhere from LEFT
pyriform sinus apex to thyroid lobe Morphology
Unilocular thin-walled unless infected Top
Differential Diagnoses Thyroglossal duct
cyst Thymic cyst 3rd branchial cleft cyst
Lymphangioma Thyroid colloid cyst Parathyroid
cyst Thyroid abscess
21
Fourth Branchial Cleft Cysts
Clinical Issues, may present as Recurrent
neck abscesses Recurrent suppurative
thyroiditis Imaging diagnosis of left thyroid
lobe abscess in pediatric patient should strongly
suggest diagnosis of infected 4th BCC