The most common histologic type of thyroid cancer is –
**Core Concept**
The question is testing the knowledge of the epidemiology of thyroid cancer, specifically the most common histologic type. Papillary thyroid carcinoma (PTC) is a well-differentiated tumor that arises from the follicular epithelium of the thyroid gland.
**Why the Correct Answer is Right**
Papillary thyroid carcinoma is the most common type of thyroid cancer, accounting for approximately 80-85% of all thyroid cancer cases. This is due to its high prevalence in the general population, particularly in women, and its tendency to occur in younger individuals. The cancer often presents with lymph node metastases and can be treated effectively with surgery, radioactive iodine ablation, and thyroid hormone suppression therapy. The characteristic histological features of PTC include nuclear grooves, pseudoinclusions, and psammoma bodies.
**Why Each Wrong Option is Incorrect**
**Option A:** Medullary thyroid carcinoma (MTC) is a less common type of thyroid cancer, accounting for approximately 3-5% of all thyroid cancer cases. It arises from the parafollicular cells of the thyroid gland, which produce calcitonin.
**Option B:** Follicular thyroid carcinoma (FTC) is a well-differentiated tumor that arises from the follicular epithelium of the thyroid gland. However, it is less common than papillary thyroid carcinoma, accounting for approximately 10-15% of all thyroid cancer cases.
**Option D:** Anaplastic thyroid carcinoma (ATC) is a highly aggressive and rare type of thyroid cancer, accounting for approximately 1-2% of all thyroid cancer cases. It arises from the follicular epithelium of the thyroid gland and is characterized by its rapid growth and poor prognosis.
**Clinical Pearl / High-Yield Fact**
The American Thyroid Association recommends that patients with thyroid nodules or cancer undergo fine-needle aspiration biopsy (FNAB) to determine the presence of malignancy. A suspicious FNAB result should prompt further investigation with imaging studies and surgical exploration.
✓ Correct Answer: C. Papillary type