A 22-year-old woman has a firm, non-tender midline submental swelling present since childhood. It moves with swallowing but does not elevate on tongue protrusion, is not fluctuant, and ultrasound shows a solid mass deep to the platysma with no connection to the hyoid bone or thyroid. What is the most likely diagnosis?
- A Submental dermoid cyst ✓
- B Thyroglossal duct cyst
- C Plunging ranula
- D Sublingual thyroid
Correct answer: A. Submental dermoid cyst
Explanation
B dermoid cyst in the submental region is a congenital inclusion cyst of ectoderm that sits superficial to the mylohyoid, moves with swallowing because of its midline location, but has no attachment to the hyoid or foramen caecum, so it does not rise with tongue protrusion. Its content is keratin and sebaceous material, giving a doughy or firm feel. B thyroglossal cyst elevates on tongue protrusion, and a plunging ranula extends laterally below the mylohyoid rather than staying midline and solid.
Reference: Bailey and Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.