8 years old male child came for ultrasound neck with c/o small cutaneous opening on right side neck and recurrent upper respiratory tract infection. The opening was there since birth but there were no symptoms.

Findings and discussion:

On B mode ultrasound images and cine:

Approx. 6-7 cm size long fistulous tract is seen on right side of neck extending from distal part of sternocleidomastoid muscle along the medial border.

Tract is seen traversing cranially up-to submandibular region.

Tract is seen along the anterior aspect of carotid vessels and seen to extend into deeper plane at the level of carotid bifurcation.

No localized collection is seen. No acute inflammatory changes seen around the tract.

Tract diameter measures 5 mm at submandibular region and approx. 2 mm near cutaneous opening.

Mildly enlarged non necrotic reactive lymph node are seen at bilateral submandibular region.

So, the diagnosis of 2nd Branchial cleft fistula is given.

A second branchial cleft sinus is a congenital anomaly resulting from incomplete obliteration of the second branchial cleft during embryonic development. It typically presents as a cyst, sinus, or fistula along the anterior border of the sternocleidomastoid muscle, near the angle of the mandible.

Ultrasound Findings of a Second Branchial Cleft Sinus

1. Location:

1. • Commonly found along the anterior border of the sternocleidomastoid (SCM) muscle, often at the level of the hyoid bone or near the angle of the mandible.
   • Can extend deep into the neck, often tracking towards the tonsillar fossa.

2. Appearance:

1. • Anechoic or Hypoechoic: If it is fluid-filled (cystic).
   • Complex with internal echoes: If infected or containing debris.
   • Well-defined margins: Suggesting a congenital origin.
   • Possible tract visualization: If a sinus or fistula is present, the ultrasound may show a hypoechoic tract extending from the skin surface to deeper structures.

3. Doppler Ultrasound:

1. • Usually shows no vascularity unless inflamed or infected.
   • Increased vascularity may indicate secondary infection.

4. Dynamic USG:

1. • Valsalva maneuver or swallowing can help assess the tract’s movement or extension towards the pharynx.

Additional Imaging

• MRI/CT with contrast may be needed for better delineation, especially for deep or complex sinus tracts.

Clinical Relevance

• If infected, the sinus can present with pain, swelling, and discharge.
• Surgical excision is often required for recurrent infections or symptomatic cases.