What is the next diagnostic test for an elderly patient with suspected anaplastic thyroid cancer presenting with dysphagia (difficulty swallowing) but no dyspnea (shortness of breath)?

Next Diagnostic Test for Suspected Anaplastic Thyroid Cancer

For an elderly patient with suspected anaplastic thyroid cancer presenting with dysphagia but no dyspnea, proceed directly to neck CT scan followed by tissue diagnosis via FNAC or core biopsy. 1

Rationale for CT Neck as Initial Imaging

CT scan of the neck is the critical first diagnostic test in this clinical scenario because it serves multiple essential functions that directly impact mortality and treatment planning:

• CT accurately determines the extent of tumor invasion into critical structures including the great vessels, trachea, esophagus, and upper aerodigestive tract—information that is essential for determining resectability, which is the primary factor affecting survival in anaplastic thyroid cancer 1, 2

• CT is superior to physical examination in detecting the true extent of disease, identifying metastatic lymph nodes (correctly identifying 14/16 cases in one series), and suggesting appropriate biopsy sites 2

• CT directly alters surgical planning in patients with intrathoracic extension or invasion of the larynx/esophagus, which is critical given that complete resection is one of the few factors that can extend survival beyond the typical 5-month median 2, 3

Why CT Takes Priority Over Other Options

FNAC (Option A) - Important but Secondary

• While FNAC is necessary for definitive diagnosis, it should follow CT imaging rather than precede it 1
• The NCCN guidelines emphasize that CT helps identify the optimal biopsy site, particularly important since anaplastic thyroid cancer can have mixed morphologies and may be difficult to distinguish from other malignancies 1, 2
• If FNA results are suspicious or non-definitive, core or surgical biopsy should be performed—but knowing the extent of disease first guides the biopsy approach 1

Ultrasound (Option C) - Limited Utility

• While ultrasound can rapidly assess tumor extension, it is inferior to CT for evaluating deep structures, vascular invasion, and retrosternal extension 1
• Ultrasound cannot adequately assess tracheal compression, esophageal invasion, or mediastinal involvement—all critical factors in anaplastic thyroid cancer 1

Open Biopsy (Option B) - Premature

• Open biopsy is reserved for cases where FNA/core biopsy is non-diagnostic 1
• Proceeding to open biopsy without imaging assessment of resectability and extent of disease is inappropriate 1

Clinical Context: Dysphagia Without Dyspnea

The presence of dysphagia suggests esophageal involvement or compression, which occurs in approximately 62% of anaplastic thyroid cancer cases 4. The absence of dyspnea is somewhat reassuring but does not exclude tracheal involvement (present in 57% of cases) 4. This clinical presentation makes CT even more critical because:

• CT can identify the specific cause of dysphagia (esophageal invasion vs. external compression) 1, 2
• Esophageal invasion affects resectability and must be known before attempting tissue diagnosis or planning treatment 2
• The patient's age and symptoms align with typical anaplastic thyroid cancer presentation (mean age 71 years, dysphagia common) 1

Recommended Diagnostic Algorithm

1. Immediate neck CT with contrast to assess:

   • Tumor extent and invasion of trachea, esophagus, larynx 1
   • Vascular involvement (carotid artery, internal jugular vein) 1, 2
   • Lymph node involvement and characteristics 4
   • Retrosternal/mediastinal extension 2

2. FNAC or core biopsy guided by CT findings to establish histologic diagnosis 1

   • Core biopsy preferred if FNA non-diagnostic 1
   • Pathology review by expert thyroid pathologist essential 1

3. PET/CT for staging after diagnosis confirmed to identify distant metastases (present in 15-50% at diagnosis) 1

Critical Pitfalls to Avoid

• Do not delay imaging to obtain tissue diagnosis first—CT findings guide biopsy approach and immediately inform prognosis 2
• Do not rely on ultrasound alone—it misses critical deep structure involvement 1
• Do not assume resectability based on physical examination—CT is superior for assessing true extent 2
• Given the median survival of only 5 months and the fact that complete resection is one of the few factors that can improve outcomes, rapid and accurate staging is paramount 1, 3

Answer: D. Neck CT