Amyloid depostion and raised serum calcitonin levels are seen in which thyroid tumor?
**Core Concept**
Amyloid deposition and raised serum calcitonin levels are characteristic features of a rare thyroid tumor. This condition is associated with a specific subtype of thyroid cancer that originates from the parafollicular cells (also known as C-cells). The parafollicular cells produce calcitonin, a hormone that plays a crucial role in calcium and phosphorus metabolism.
**Why the Correct Answer is Right**
The correct answer is associated with medullary thyroid carcinoma (MTC), a type of thyroid cancer that arises from the parafollicular cells. MTC is known to cause amyloid deposition in the tumor stroma, which is a characteristic histopathological feature. Additionally, elevated levels of serum calcitonin are a hallmark of MTC, as the tumor cells continue to produce and secrete this hormone. The high levels of calcitonin can be used as a diagnostic marker for MTC.
**Why Each Wrong Option is Incorrect**
**Option A:** Papillary thyroid carcinoma is a common type of thyroid cancer, but it is not associated with amyloid deposition or elevated serum calcitonin levels. Papillary thyroid carcinoma typically arises from the follicular cells of the thyroid gland.
**Option B:** Follicular thyroid carcinoma is another type of thyroid cancer that originates from the follicular cells, but it does not typically cause amyloid deposition or elevated serum calcitonin levels.
**Option C:** Anaplastic thyroid carcinoma is a rare and aggressive type of thyroid cancer, but it is not specifically associated with amyloid deposition or elevated serum calcitonin levels.
**Clinical Pearl / High-Yield Fact**
When suspecting a thyroid tumor, it's essential to investigate serum calcitonin levels, especially in patients with a family history of medullary thyroid carcinoma or those with a personal history of MTC. Elevated calcitonin levels can aid in the diagnosis and help differentiate MTC from other types of thyroid cancer.
**Correct Answer: D. Medullary thyroid carcinoma.**