A most common subtype of thyroid cancer is?
**Core Concept**
Thyroid cancer is a malignant neoplasm originating from the thyroid gland, which is responsible for hormone regulation. The most common subtype of thyroid cancer is characterized by its slow growth and low mortality rate.
**Why the Correct Answer is Right**
The correct answer is Papillary thyroid carcinoma (PTC), which accounts for approximately 80-85% of all thyroid cancer cases. PTC is a well-differentiated cancer with a propensity for lymph node metastasis but a relatively good prognosis. The cancer cells in PTC often exhibit characteristic nuclear features such as overlapping nuclei, ground-glass appearance, and psammoma bodies. The BRAF V600E mutation is a common genetic alteration in PTC, contributing to its pathogenesis.
**Why Each Wrong Option is Incorrect**
**Option A:** Follicular thyroid carcinoma (FTC) is a less common subtype, accounting for approximately 10-15% of thyroid cancer cases. It tends to spread through the bloodstream rather than lymph nodes.
**Option B:** Medullary thyroid carcinoma (MTC) arises from the parafollicular cells (C cells) of the thyroid gland and accounts for 3-10% of thyroid cancer cases. It often presents with a family history of MTC or multiple endocrine neoplasia (MEN).
**Option C:** Anaplastic thyroid carcinoma (ATC) is a highly aggressive and rare subtype, accounting for less than 1% of thyroid cancer cases. It is characterized by rapid growth and poor prognosis.
**Clinical Pearl / High-Yield Fact**
The American Thyroid Association recommends total thyroidectomy as the primary treatment for PTC, especially in cases with lymph node metastasis or extrathyroidal extension.
**Correct Answer: D. Papillary thyroid carcinoma (PTC)**