Papillary ca thyroida) Most common thyroid cancerb) Psammoma bodies seenc) Encapsulatedd) Blood borne metastasis is common
**Core Concept**
Papillary thyroid carcinoma (PTC) is a type of well-differentiated thyroid cancer characterized by its unique histological features and clinical behavior. PTC accounts for approximately 80-85% of all thyroid cancer cases and is known for its slow growth and potential for lymph node metastasis.
**Why the Correct Answer is Right**
Papillary thyroid carcinoma is indeed the most common type of thyroid cancer, with a high incidence rate worldwide. The presence of psammoma bodies, which are small, concentrically laminated calcifications, is a characteristic histopathological feature of PTC. Encapsulated tumors are not exclusive to PTC, but they can be found in this type of cancer. However, blood-borne metastasis is not common in PTC, as it primarily spreads through lymphatic routes.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as PTC is not the most common thyroid cancer type in all populations, although it is the most common in many regions.
**Option C:** While encapsulation can be observed in PTC, it is not a defining characteristic of this cancer type.
**Option D:** Blood-borne metastasis is not typical of PTC, which usually spreads through lymphatic channels.
**Clinical Pearl / High-Yield Fact**
A key feature of PTC is its tendency to spread to regional lymph nodes, especially the central compartment, which is why thorough lymph node dissection is often performed during surgery.
**Correct Answer: A. Papillary ca thyroid**