**Question:** Papillary carcinoma thyroid:

a. Most common thyroid cancer
b. Psammoma bodies seen
c. Encapsulated
d. Blood borne metastasis is common

**Correct Answer:**

**Core Concept:** Papillary carcinoma thyroid is the most common type of thyroid cancer. It originates from the follicular cells of the thyroid gland, which produce thyroid hormones.

**Why the Correct Answer is Right:**

Papillary carcinoma thyroid is the most common thyroid cancer due to several reasons:

1. **a. Most common thyroid cancer:** This is due to the high prevalence of this type of thyroid cancer in the general population. It represents around 80-85% of all thyroid cancers.
2. **b. Psammoma bodies seen:** Psammoma bodies are commonly found in papillary carcinoma thyroid. These are calcified structures within the tumor that can be seen on imaging studies or histopathology.
3. **c. Encapsulated:** Papillary carcinoma thyroid is typically encapsulated, meaning the tumor is surrounded by a fibrous capsule, which helps to limit its growth and spread.
4. **d. Blood borne metastasis is common:** Papillary carcinoma thyroid has a tendency to spread through the bloodstream, leading to distant organ involvement, particularly the lungs, bones, and brain.

**Why Each Wrong Answer is Incorrect:**

1. **a. Most common thyroid cancer (incorrect):** Although papillary carcinoma thyroid is common, follicular carcinoma thyroid is less common but equally important to know, as it represents the second most common type of thyroid cancer (10-15% of cases).
2. **b. Psammoma bodies seen (incorrect):** Although psammoma bodies can be seen in papillary carcinoma thyroid, they are not exclusively present in this type of cancer. They can also be found in other types of thyroid cancer, like oxyphil cell carcinoma and medullary carcinoma.
3. **c. Encapsulated (incorrect):** Although papillary carcinoma thyroid is often encapsulated, it is not always encapsulated. Some cases of this cancer can be unencapsulated, invading surrounding tissue and potentially spreading locally.
4. **d. Blood borne metastasis is common (incorrect):** Although papillary carcinoma thyroid has a higher potential for blood-borne spread compared to other thyroid cancers, the incorrect statement is that it has common blood-borne spread. This type of cancer can still behave in a localized manner in many cases and may present as a single nodule or multiple nodules within the thyroid gland.

**Clinical Pearls:**

1. Papillary carcinoma thyroid is a well-differentiated thyroid cancer that develops from the follicular cells of the thyroid gland. It is a slow-growing cancer with an indolent behavior, often presenting as a single or multiple nodules within the thyroid gland.
2. Psammoma bodies are calcified structures that can be seen in various types of thyroid cancer, including papillary carcinoma thyroid, oxyphil cell carcinoma, and medullary carcinoma.
3. Although encapsulation is common in papillary carcinoma thyroid, it is not always present, and the