**Core Concept**
Medullary thyroid carcinoma (MTC) arises from the parafollicular cells (also known as C cells) of the thyroid gland. These cells produce calcitonin, a hormone involved in calcium and phosphorus metabolism. In MTC, abnormal calcitonin production leads to amyloid deposition in the stroma of the tumor.

**Why the Correct Answer is Right**
In MTC, the excessive production of calcitonin leads to its deposition in the form of amyloid fibrils within the tumor stroma. This characteristic amyloid deposition is a hallmark of MTC and can be detected by immunohistochemical staining for calcitonin. The amyloid fibrils in MTC are composed of calcitonin peptides that have undergone misfolding and aggregation. This unique feature is used to distinguish MTC from other types of thyroid carcinomas.

**Why Each Wrong Option is Incorrect**
**Option A:** Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer and is characterized by papillary projections and nuclear grooves, but it is not associated with calcitonin-induced amyloid deposition.

**Option B:** Follicular thyroid carcinoma (FTC) arises from the follicular cells of the thyroid gland and is characterized by capsular and vascular invasion, but it does not produce calcitonin and therefore does not lead to amyloid deposition.

**Option C:** Anaplastic thyroid carcinoma (ATC) is a highly aggressive and poorly differentiated type of thyroid cancer, but it is not specifically associated with calcitonin-induced amyloid deposition.

**Clinical Pearl / High-Yield Fact**
MTC is a type of thyroid carcinoma that can be inherited in an autosomal dominant pattern due to mutations in the RET proto-oncogene. Early detection and treatment of MTC are crucial to prevent complications and improve patient outcomes.

**Correct Answer:** C.