Fourth Branchial Cleft Cyst

  • Etiology:
    — Remnant of embryonal branchial arch incompletely obliterated
    — Courses from apex of pyriform sinus to lower anterior neck and thyroid
  • Imaging:
    — Usually in left upper thyroid
    — Look from pyriform sinus to left thyroid
    — Often see an abscess
    — Look for pyriform sinus fistula (fourth branchial pouch) appearing as infiltrative left neck mass above thyroid with collapse of left pyriform sinus
  • DDX:
  • Complications: Infection
  • Treatment:
  • Clinical:
    — 2% of branchial cleft cysts
    — Presents with recurrent supprative thyroiditis or abscess
    — With unexplained abscess in the neck look for branchial cleft anomaly

Radiology Cases of Fourth Branchial Cleft Cyst

CT of fourth branchial cleft cyst
Coronal (above left), sagittal (above right) and axial (below) CT with contrast of the neck degraded by motion artifact shows a round, low density mass in the neck inferior to the hyoid bone and anterior to the thyroid gland that is just to the left of midline that has rim enhancement. Endoscopy subsequently showed a tract to the left pyriform sinus.