Classical branchial fistula

Definition

Classical course

• External opening: anterior border of lower third of sternocleidomastoid (SCM)
• Passes deep to platysma, between internal and external carotid arteries
• Opens internally in the tonsillar fossa, near the posterior faucial pillar

Presentation

• Usually child or young adult
• Small pit/opening at lower anterior border of SCM
• Recurrent mucoid or mucopurulent discharge from opening
• Discharge may increase during upper respiratory infection
• May get recurrent infection, swelling, pain, or abscess
• Usually unilateral, rarely bilateral

Investigations

• Mainly clinical diagnosis
• Fistulogram/sinogram: water-soluble contrast injected through external opening delineates tract and may show communication with tonsillar fossa
• Ultrasound: identifies cystic component/collection
• CT fistulography or contrast CT neck: useful for defining extent and relation to carotid vessels, especially recurrent or complex lesions
• Examine oral cavity and tonsillar fossa; endoscopy if internal opening is suspected

Management

• Treat acute infection first: antibiotics, and drainage if abscess is present
• Definitive treatment: complete surgical excision of the tract after infection settles
• Often performed by step-ladder transverse neck incisions to trace and remove the whole tract up to the pharyngeal end
• Incomplete removal leads to recurrence

1. Causes of lateral neck swelling

In children

• Cervical lymphadenopathy: reactive following URTI, bacterial lymphadenitis, tuberculosis
• Congenital lesions: branchial cyst/sinus/fistula, cystic hygroma (lymphatic malformation), dermoid cyst
• Vascular lesions: haemangioma, venous malformation
• Salivary gland disease: parotitis
• Neoplasms: lymphoma, rhabdomyosarcoma, neuroblastoma metastasis

In adults

• Cervical lymph nodes
  • Reactive/infective: dental infection, TB, HIV, etc.
  • Metastatic lymph nodes from head and neck squamous cell carcinoma: consider especially in patients >40 years, smokers, alcohol use, or a persistent hard node
  • Lymphoma
• Branchial cyst, often presents in young adults
• Salivary gland tumour, especially parotid tumour
• Thyroid malignancy with nodal metastasis
• Neurogenic tumours: schwannoma, carotid body tumour
• Laryngocele
• Lipoma and other soft-tissue tumours

2. Thyroglossal fistula

Clinical presentation

• Usually follows infection and rupture of a thyroglossal duct cyst, or follows incision/drainage or incomplete excision of a cyst.
• A small discharging opening in the midline of neck, classically just below the hyoid bone.
• Opening may be indrawn and covered by a crescentic skin fold.
• Intermittent mucoid, mucopurulent, or purulent discharge.
• May have recurrent infection, pain, redness, or previous midline neck swelling.
• The tract/opening moves upwards on:
  • Swallowing
  • Protrusion of tongue: characteristic clinical sign due to attachment along the thyroglossal duct tract.

Investigations

• Ultrasound neck: first-line. Confirms cystic lesion/tract and, importantly, confirms a normally located thyroid gland.
• Fistulogram/sinogram with water-soluble contrast: delineates the tract in a persistent discharging fistula.
• Thyroid function tests: if thyroid disease is suspected.
• Thyroid radionuclide scan: if ultrasound fails to show normal thyroid tissue or ectopic thyroid is suspected.
• CT/MRI neck: for recurrent, complex, deep, or suspicious lesions.
• Send discharge for culture if actively infected.

3. Other fistulae/sinuses seen in the neck

• Branchial fistula: lateral neck opening at lower anterior border of SCM, classically communicates with tonsillar fossa.
• Thyroglossal fistula: midline, usually below hyoid.
• Piriform sinus fistula: usually left-sided; presents with recurrent acute suppurative thyroiditis or recurrent deep-neck infection.
• Congenital tracheo-oesophageal fistula: presents in neonates with choking, coughing, cyanosis during feeding and aspiration.
• Salivary fistula: acquired, usually after parotid trauma, surgery, or infection; saliva discharges through skin, often increases during meals.
• Pharyngocutaneous fistula: acquired complication after laryngectomy or pharyngeal surgery.