What is the most appropriate next step for a patient with a 7mm solid neck mass and regular margins, who is asymptomatic, after a neck ultrasound?

Check TSH First

For an asymptomatic patient with a 7mm solid neck mass with regular margins on ultrasound, the most appropriate next step is to check TSH (Option C), as this mass is most likely thyroid in origin and requires functional assessment before any invasive procedures. 1

Why TSH is the Correct Initial Step

• The 7mm size is below the threshold for high-risk features: The American Academy of Otolaryngology-Head and Neck Surgery defines masses >1.5 cm (15mm) as a physical examination characteristic indicating increased risk for malignancy. 2 This 7mm mass is less than half that threshold.

• Regular margins suggest benign pathology: The description of "regular margins" on ultrasound does not meet the high-risk criteria of fixation to adjacent tissues, firm consistency, or ulceration of overlying skin that would trigger immediate advanced imaging or FNA. 2

• Thyroid nodules require functional assessment first: When a neck mass is suspected to be thyroid in origin (which a small, solid mass with regular margins typically is), thyroid function testing with TSH is the standard initial step before proceeding to more invasive procedures. 1

Why Other Options Are Not Appropriate at This Stage

FNA (Option A) is premature because:

• The American Academy of Otolaryngology-Head and Neck Surgery strongly recommends FNA for patients with neck masses deemed at increased risk for malignancy, specifically when the diagnosis remains uncertain after initial evaluation. 2, 3
• This patient does not meet high-risk criteria: the mass is <1.5 cm, has regular margins, and the patient is asymptomatic. 2

CT scan (Option D) is not indicated because:

• The American Academy of Otolaryngology-Head and Neck Surgery issues a strong recommendation for CT neck with contrast (or MRI) specifically for patients with neck masses deemed at increased risk for malignancy. 2
• This small mass with benign features does not warrant the radiation exposure and cost of CT imaging at this stage. 2

Thyroid scintigraphy (Option B) is not the first step because:

• Functional assessment with TSH should precede scintigraphy in the evaluation algorithm for thyroid masses. 1
• Scintigraphy is typically reserved for cases where TSH is suppressed or when determining if a nodule is functioning ("hot") or non-functioning ("cold"). 1

Clinical Reasoning Algorithm

1. First, determine if the mass meets high-risk criteria: Size >1.5 cm, fixation to adjacent tissues, firm consistency, ulceration of overlying skin, or duration ≥2 weeks without infectious etiology. 2

2. If high-risk features are absent (as in this case): Proceed with conservative evaluation starting with thyroid function testing if thyroid origin is suspected. 1

3. If high-risk features are present: Proceed directly to contrast-enhanced CT or MRI, followed by FNA if diagnosis remains uncertain. 2

Important Caveats

• Follow-up is mandatory: Even though this mass appears low-risk, the American Academy of Otolaryngology-Head and Neck Surgery recommends that clinicians document a plan for follow-up to assess resolution or final diagnosis for patients not at increased risk for malignancy. 2

• Reassess if the mass changes: If the mass increases in size, becomes fixed, develops concerning features, or persists beyond expected timeframes, escalate to imaging and/or FNA. 2

• Don't prescribe antibiotics without infection: The American Academy of Otolaryngology-Head and Neck Surgery explicitly recommends against routinely prescribing antibiotics for neck masses unless there are clear signs and symptoms of bacterial infection (warmth, erythema, tenderness, fever). 2