Congenital Neck Lesions

Embryology & Overview - Genesis of Lumps

• Embryological remnants: Key to congenital neck masses.
• Pharyngeal (Branchial) Apparatus:
  • Clefts (ectoderm), Arches (mesoderm/neural crest), Pouches (endoderm).
  • Persistence/malformation → cysts, sinuses, fistulae.
• Thyroid Descent:
  • Foramen cecum → thyroglossal duct.
  • Remnant → Thyroglossal Duct Cyst (TGDC), often midline.
• Other sources:
  • Dermoid/Epidermoid: Ectodermal rests.
  • Lymphatic Malformations: Abnormal lymphatic development.

⭐ Thyroglossal duct cysts are the most common pediatric congenital neck masses, usually presenting before age 5.

Thyroglossal Duct Cysts - Tongue's Tail Tale

• Embryology: Arises from persistent thyroglossal duct, tracking thyroid's descent from foramen cecum (base of tongue) to its final position in the neck.
• Location: Typically midline (90%), most commonly infrahyoid (60-80%). Can occur anywhere along the duct's path.
• Clinical Features:
  • Painless, smooth, fluctuant, mobile cystic mass.
  • Characteristic: Moves upwards with tongue protrusion and swallowing.
  • May present with infection (pain, redness, tenderness) or a draining sinus.
• Diagnosis: Primarily clinical. Ultrasound (USG) confirms cystic nature & assesses thyroid gland. CT/MRI for complex cases.
• Treatment: Sistrunk procedure - surgical excision of the cyst, the entire duct tract up to the foramen cecum, and the central portion of the hyoid bone to prevent recurrence.

⭐ The Sistrunk procedure, including hyoid bone resection, significantly reduces recurrence rates compared to simple cystectomy (recurrence <5% vs. 20-50%).

Branchial Cleft Anomalies - Gill Echoes

• Embryonic remnants of the pharyngeal (branchial) apparatus; present as cysts, sinuses, or fistulae.
• Types & Features:

  Type	Origin	Course Highlights	Ext. Opening (Typically Ant. Border SCM)	Int. Opening	Notes
  1st	1st cleft	Parallels External Auditory Canal (EAC); near facial nerve.	Pre/infra-auricular, angle of mandible.	EAC/Middle ear	Least common.
  2nd	2nd cleft	From tonsillar fossa, b/w Internal/External Carotid Arteries (ICA/ECA), over CN IX & XII.	Lower 1/3 SCM.	Tonsillar fossa	Most common (95%).
  3rd	3rd cleft	From pyriform sinus, posterior to ICA, pierces thyrohyoid membrane.	Lower 1/3 SCM.	Pyriform sinus (inf.)	Rare.
  4th	4th cleft	From apex of pyriform sinus, hooks around subclavian artery (Right) / aortic arch (Left).	Lower neck/thyroid area.	Apex pyriform sinus	Rarest (Left > Right).

• Clinical Features: Painless, fluctuant lateral neck mass; may enlarge with Upper Respiratory Infection (URI). Sinus/fistula may have mucoid discharge.
• Diagnosis: Primarily clinical. CT/MRI to delineate tract. Fistulogram can be used.
• Management: Complete surgical excision of the cyst and entire tract.

  ⭐ Second branchial cleft anomalies are the most frequent type, accounting for approximately 95% of all branchial cleft anomalies.

Lymphatic & Vascular Malformations - Spongy Swells

• Lymphatic Malformations (LM) / Cystic Hygroma:
  • Soft, spongy, compressible mass; brilliantly transilluminant.
  • Types: Macrocystic (>1-2 cm cysts, good sclerotherapy response e.g. OK-432), Microcystic (<1-2 cm cysts, infiltrative, surgery often).
  • Location: Posterior triangle (most common, ~75%), axilla.
  • Complications: Infection, hemorrhage, airway compromise.
  • Management: Sclerotherapy, surgical excision.

  ⭐ Cystic hygroma (macrocystic LM) is the most common LM, typically in posterior triangle; can cause airway obstruction.

• Hemangiomas:
  • Infantile (IH): Appears postnatally, proliferates (1st year), then involutes (by age 5-7). Rx: Propranolol for problematic IH (airway, vision, ulceration, PHACES).
  • Congenital (CH): Fully formed at birth. Types: RICH (Rapidly Involuting), NICH (Non-Involuting).
  • 📌 PHACES Syndrome: Posterior fossa, Hemangiomas (large facial), Arterial, Cardiac, Eye, Sternal.

Other Congenital Lesions - Rare Neck Finds

• Dermoid/Epidermoid Cysts:
  • Midline (dermoid common) or lateral (epidermoid).
  • Features: slow-growing, non-tender, doughy feel.
• Teratomas:
  • Contain elements from all 3 germ cell layers.
  • May cause neonatal respiratory distress if large.
• Laryngoceles:
  • Air-filled sacs; internal, external, or mixed.
  • Enlarge with ↑ intrathoracic pressure (Valsalva).

⭐ Dermoid cysts are typically midline, often suprahyoid, and may contain skin adnexa like hair follicles or sebaceous glands; they do not move with tongue protrusion, unlike thyroglossal duct cysts (TGDC).

High‑Yield Points - ⚡ Biggest Takeaways

• Thyroglossal duct cysts are midline, move with tongue protrusion, and require Sistrunk procedure.
• Branchial cleft cysts are lateral, anterior to SCM, most commonly from the second arch.
• Cystic hygromas (lymphangiomas) are posterior triangle lesions, transilluminate, and associated with Turner syndrome.
• Dermoid cysts are midline, feel doughy, and contain skin appendages.
• Laryngoceles are air-filled sacs, worsen with Valsalva, and can be internal, external, or mixed.
• Infantile hemangiomas are common; propranolol is first-line treatment for problematic lesions.