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Transcript
Branchial Cleft Cysts
David M. Chaky, MD
Dept. of Radiology, UNC Chapel Hill
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.
• 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 endodermallined pharyngeal pouches.
• By the end of the 4th week of gestation, 4 welldefined pairs of branchial arches are visible
externally; the 5th and 6th arches are small and
cannot be seen on the embryonic surface.
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.
Common Lateral Neck Masses
in Infancy
•
•
•
•
Branchial cleft anomalies
Laryngoceles
Dermoid and Teratoid Cysts
Sternocleidomastoid Pseudotumor of
Infancy (fibromatosis colli)
• Plunging ranulas
• Adenopathy
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
First Branchial Cleft Cysts
• Type I
Ectodermal Duplication anomaly of the EAC
with squamous epithelium only.
o Parallel to the EAC
o Pretragal, post auricular
o Connection with TM or Malleus>Incus
o Surgical Excision
o
First Branchial Cleft Cysts
• Type II
o
o
o
o
o
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
First Branchial Cleft Cyst,
Type 2
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
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
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!)
Second Branchial Cleft Cysts
Second Branchial Cleft Cysts
• * Epidemiology: 2nd BCC account for > 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
Third Branchial Cleft Cysts
• Rare (<2%)
• 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
Third Branchial Cleft Cysts
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
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.
Fourth Branchial Cleft Cysts
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
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