090809 Esnr Meeting: Congenital Cysts Of The Head And Neck

1.  To review the normal anatomy of the branchial clefts and arches (BA) with embryological correlation. 2.  To illustrate the imaging findings in classic congenital cystic masses affecting the head and neck. 3.  To discuss the list of differential diagnosis when examining congenital cysts of the head and neck.

The main bony structures of the BA consist of a maxillary process and a mandibular process. The mesenchyme of the maxillary process gives rise to the maxilla, zygomatic bone and part of the temporal bone through membranous ossification. The mandible is also formed by membranous ossification of mesenchymal tissue surrounding Meckel’s cartilage.

TMJ

A 2nd BCC is the most common BCC accounting for >90% of all BCC anomalies. It is considered a failure of closure of the cervical sinus. Typically presents as a painless mass along the sternocleidomastoid (SCM), but may become infected.

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Retention cyst with epithelial lining resulting from trauma or inflammation of sublingual gland or minor salivary glands. May rupture out posteriorly into submandibular space creating a pseudocyst lacking epithelial lining.

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Maxilla 16d

Ramus of mandible

Intermaxillary suture

Angle of mandible Mandibular symphysis

Body of mandible

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Mental tubercle

Mental foramen

Hyoid 1

Zygomatic arch

TMJ Ramus of mandible

Orbitomeatal plane

Remnant of thyroglossal duct found between foramen cecum of tongue base & thyroid bed in infrahyoid neck. A failure of involution of the TGD & persistent secretion of epithelial cells lining the duct. Can occur anywhere along route of descent of the TGD. Most often embedded in the infrahyoid strap muscles. Can be associated with thyroid carcinomas.

Dermoid cyst are rare congenital lesions derived from ectodermal differentiation. Thought to occur in this location due to incarcerated pluripotent tissue during fusion of 1st & 2nd BA. Only a minority are seen in this location. The most frequent location in the head & neck is the peri-orbital region.

Condylar process

Angle of mandible

Coronoid process

Body of mandible

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Hyoid 2 11a

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Lymphangiomas are spectrum of congenital lesions, differentiated by size of dilated lymphatic channels. Uni- or multiloculated nonenhancing insinuating cystic neck mass which may occur in any head & neck space but usually occur in more than one space. Submandibular space most common followed by sublingual space. Seen in Turner syndrome. Thought to be due to embryonic lymph sacs left behind in embryogenesis.

The BA, also called pharyngeal arches, develops in early fetal life. The BAs develop in the 4th and 5th weeks of development. The 1st BA is located between the stomodeum and the first pharyngeal groove. This arch divides into a maxillary and a mandibular process. The maxillary process becomes the maxilla and palate. The 2nd BA or hyoid arch gives rise to the stapes, styloid process and upper part of the body of the hyoid. 11c

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Cystic neck mass found along course of embryologic tract from pyriform sinus to mediastinum which results from failure of complete involution of thymopharyngeal duct. Typically seen as a nonenhancing cystic mass in lateral infrahyoid neck often adjacent to the carotid space.

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A 1st BCC is a cystic mass that arise in the parotid, posterior submandibular space or preauricular region. It is a remnant of the 1st branchial cleft due to incomplete closure in utero. Rare congenital (typically acquired) thin walled air or fluidfilled cystic lesion communicating with laryngeal ventricle in the paraglottic or submandibular space. Appendix of the laryngeal ventricle (aka saccule) is site of origin of laryngocele.

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StatDx. Amirsys, Inc.; 2009 Alvi A, Weissman J, Myssiorek D, Narula S, Myers EN. Computed tomographic and magnetic resonance imaging characteristics of laryngocele and its variants. American journal of otolaryngology 1998;19:251-256 Behl A. Giant Epidermoid Cyst of the Floor of Mouth. MJAFI 2001;57:247-249 Brauchle RW, Risin SA, Ghorbani RP, Pereira KD. Cervical thoracic duct cysts: a case report and review of the literature. Archives of otolaryngology--head & neck surgery 2003;129:581-583 5. Glastonbury CM, Davidson HC, Haller JR, Harnsberger HR. The CT and MR imaging features of carcinoma arising in thyroglossal duct remnants. Ajnr 2000;21:770-774 6. Larsen WJ. Human embryology. New York: Churchill Livingstone; 1993 7. Lev S, Lev MH. Imaging of cystic lesions. Radiologic clinics of North America 2000;38:1013-1027 8. Macdonald AJ, Salzman KL, Harnsberger HR. Giant ranula of the neck: differentiation from cystic hygroma. Ajnr 2003;24:757-761 9. Moore KL, Dalley AF. Clinically oriented anatomy. Philadelphia: Lippincott Williams & Wilkins; 1999 10. Sadler TW, Langman J. Langman's medical embryology. 10th ed. Philadelphia: Lippincott Williams & Wilkins; 2006;xiii, 371 p. 11. Som PM, Curtin HD. Head and neck imaging. St. Louis, Mo.: Mosby; 2003 3. 4.

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The first branchial arch is the first of six branchial arches and is the embryological origin of most of the structures of the face. A wide variety of congenital conditions may arise from its contents. Understanding of the anatomic formation of this region is important in understanding abnormalities in development which aids in formation of a precise diagnoses and lists of differentials.

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