Question

A patient has a neck mass with odynophagia and dyspnea. Histology shows amyloid deposition. What is the most likely diagnosis?

• A. Papillary thyroid carcinoma
• B. Follicular thyroid carcinoma
• C. Medullary thyroid carcinoma
• D. Anaplastic thyroid carcinoma

Hint:

Thyroid tumor with amyloid stroma = medullary thyroid carcinoma.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The presence of "amyloid stroma" in a thyroid tumor is a highly specific histological marker for one particular type of thyroid cancer.
Step 2: Detailed Explanation:

Medullary Thyroid Carcinoma (MTC): This tumor arises from the parafollicular C-cells, which produce calcitonin.

Amyloid Stroma: The C-cells secrete procalcitonin, which undergoes limited proteolysis and deposits within the tumor stroma as amyloid. This amyloid shows characteristic apple-green birefringence under polarized light with Congo Red stain.

Genetics: MTC can be sporadic or associated with MEN 2A/2B syndromes (germline RET proto-oncogene mutations).

Differential - Papillary: Shows "Orphan Annie eye" nuclei and Psammoma bodies.

Differential - Follicular: Characterized by capsular or vascular invasion.

Differential - Anaplastic: Highly aggressive, pleomorphic cells; usually occurs in older patients and lacks amyloid.

Step 3: Final Answer:
Histological evidence of amyloid in a thyroid mass is diagnostic of Medullary Thyroid Carcinoma.