Which of the following features is NOT seen in papillary carcinoma thyroid?
**Core Concept**
Papillary thyroid carcinoma (PTC) is a type of well-differentiated thyroid cancer characterized by its distinct histological features and molecular markers. The question requires the test-taker to identify a characteristic not typically associated with PTC.
**Why the Correct Answer is Right**
Papillary thyroid carcinoma is known for its papillary architecture, presence of nuclear grooves, and intranuclear pseudoinclusions. It also often exhibits a characteristic nuclear feature known as **Orphan Annie eye nuclei**, where the nucleus appears empty or cleared out. Additionally, PTC frequently shows **psammoma bodies**, which are small, concentrically laminated calcifications. These features are diagnostic hallmarks of PTC.
**Why Each Wrong Option is Incorrect**
**Option A:** Psammoma bodies are indeed seen in PTC, making this option incorrect.
**Option B:** Intranuclear pseudoinclusions are a characteristic feature of PTC, so this option is also incorrect.
**Option C:** While not exclusive to PTC, the presence of nuclear grooves is a common feature in PTC, making this option incorrect as well.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that papillary thyroid carcinoma often exhibits a **"tall cell" morphology**, characterized by cells with a high nuclear-to-cytoplasmic ratio and elongated papillae. This feature can be a diagnostic clue in cases where the classic papillary architecture is not evident.
**Correct Answer:** C.