A patient reports a swelling in the midline of the neck. The pain worsens when eating. On palpation the mass is soft. Which is the MOST likely diagnosis?

Correct answer: B. Submandibular gland obstruction (sialolithiasis / sialadenitis)

• A. Reactive lymph nodes are firm, mobile, and tied to infection/inflammation — not to meals.
• B. Correct. Pain that worsens specifically with eating is the hallmark of an OBSTRUCTED salivary gland (mealtime swelling/pain): saliva production rises during eating, but a stone blocks outflow, so the gland swells and hurts. The submandibular gland is the most common site for stones.
• C. A thyroglossal duct cyst is the classic MIDLINE neck mass that moves with swallowing and tongue protrusion — but it is typically painless and is NOT made worse by eating. The 'midline' wording fits it, which is exactly why it is the tempting distractor here.
• D. A branchial cleft cyst presents LATERALLY (along the anterior border of the sternocleidomastoid), not in the midline, and is not eating-related.

Note: FLAG — internally inconsistent source item. 'Midline neck mass' screams thyroglossal duct cyst (a guaranteed board buzzword), but 'pain worse when eating' is pathognomonic for salivary obstruction. The two clues point to different diagnoses. The next question's confirming test (occlusal floor-of-mouth radiograph) only makes sense for a submandibular stone, so this item has been keyed to the salivary interpretation for coherence. Know BOTH: midline + moves with tongue protrusion = thyroglossal cyst; mealtime pain/swelling = salivary stone.