Endocrine Surgery Practice Questions

Q: Which of the following is the most common histologic type of thyroid cancer?

Papillary type. **Explanation:** **Papillary Thyroid Carcinoma (PTC)** is the most common histological type of thyroid cancer, accounting for approximately **80–85%** of all thyroid malignancies. Its high prevalence is attributed to its association with radiation exposure and specific genetic mutations (e.g., BRAF, RET/PTC rearrangements). It typically presents as a slow-growing, painless thyroid nodule and has an excellent prognosis. **Analysis of Options:** * **A. Anaplastic type:** This is the rarest (<2%) but most aggressive form. It typically occurs in elderly patients and carries a very poor prognosis due to rapid local invasion. * **B. Medullary type:** Accounting for about 5–10% of cases, this arises from the parafollicular C-cells (secreting Calcitonin). It can be sporadic or associated with MEN 2A/2B syndromes. * **C. Follicular type:** The second most common type (10–15%). It is characterized by hematogenous spread (to bone and lungs) rather than lymphatic spread, which is more common in PTC. **High-Yield Clinical Pearls for NEET-PG:** * **Hallmark Histology:** Look for **Orphan Annie eye nuclei** (empty-appearing nuclei), **Psammoma bodies** (laminated calcifications), and **Nuclear grooves**. * **Spread:** PTC primarily spreads via the **lymphatics** to cervical lymph nodes. * **Risk Factor:** History of childhood **ionizing radiation** to the neck is a major risk factor. * **Prognosis:** PTC has the best prognosis among all thyroid cancers, with a 10-year survival rate exceeding 90%. * **Investigation of Choice:** Fine Needle Aspiration Cytology (FNAC) is the gold standard for diagnosis (Note: FNAC cannot distinguish between follicular adenoma and carcinoma).

Q: What is the typical thyroid status in patients with thyroid carcinoma?

Usually euthyroid. **Explanation:** The thyroid status in patients with thyroid carcinoma is **usually euthyroid**. This is because thyroid malignancies (such as Papillary, Follicular, or Medullary carcinoma) typically arise from a localized clone of cells that do not interfere with the overall hormone-producing capacity of the remaining normal thyroid parenchyma. Furthermore, most thyroid cancer cells are less efficient at iodine uptake and thyroid hormone synthesis than normal follicular cells. **Analysis of Options:** * **Option A (Hypothyroidism):** Thyroid cancer rarely causes hypothyroidism because it seldom involves the entire gland extensively enough to destroy all functional tissue. Hypothyroidism is more commonly associated with autoimmune conditions like Hashimoto’s thyroiditis. * **Option B (Hyperthyroidism):** Most thyroid cancers are "cold" nodules on scintigraphy, meaning they do not produce excess hormones. While rare cases of functioning follicular carcinomas exist, they are exceptions rather than the rule. * **Option D (Toxic Nodules):** Toxic nodules (Plummer’s disease) are almost always benign. The risk of malignancy in a "hot" or hyperfunctioning nodule is extremely low (<1%). **Clinical Pearls for NEET-PG:** * **The "Cold Nodule" Rule:** On a Technetium-99m or Iodine-123 scan, most thyroid cancers appear as **"cold" nodules** (non-functioning). A cold nodule has a 15-20% risk of malignancy, whereas a hot nodule is rarely malignant. * **Initial Investigation:** The first step in evaluating a thyroid nodule is a **Serum TSH level**. If TSH is normal (euthyroid), the next step is a **Fine Needle Aspiration Cytology (FNAC)**, which is the gold standard for diagnosis. * **Exception:** In Medullary Thyroid Carcinoma (MTC), patients are euthyroid but may have elevated **Calcitonin** levels, which serves as a tumor marker.

Q: Which type of thyroid carcinoma commonly presents with blood-borne metastasis?

Follicular. **Explanation:** The correct answer is **Follicular Thyroid Carcinoma (FTC)**. The fundamental concept to remember for thyroid malignancies is the route of spread: **Papillary spreads via lymphatics, while Follicular spreads via the bloodstream.** 1. **Why Follicular is Correct:** FTC is characterized by its tendency for **angioinvasion** (invasion into blood vessels). Because of this, it bypasses the regional lymph nodes and spreads via the hematogenous route. The most common sites for distant metastasis in FTC are the **bones** (often presenting as osteolytic, pulsating lesions) and the **lungs**. 2. **Why the others are Incorrect:** * **Papillary (B):** This is the most common thyroid cancer. It primarily spreads via the **lymphatic system** to the cervical lymph nodes. While distant blood-borne spread can occur (especially to the lungs), it is not the characteristic or "common" initial presentation compared to FTC. * **Mixed (C):** Most mixed patterns behave similarly to Papillary carcinoma and follow lymphatic spread. * **Medullary (D):** Arising from parafollicular C-cells, it spreads via both lymphatic and hematogenous routes, but it is classically associated with early nodal involvement and is less common than FTC. **High-Yield Clinical Pearls for NEET-PG:** * **Psammoma bodies** are a hallmark of Papillary, not Follicular. * **Orphan Annie eye nuclei** and **nuclear grooves** are diagnostic for Papillary. * FTC cannot be diagnosed by FNAC because FNAC cannot identify **capsular or vascular invasion**; a formal histological biopsy (lobectomy) is required. * **Hürthle cell carcinoma** is a variant of FTC that also spreads hematogenously but has a higher rate of lymph node metastasis than typical FTC.

Q: Which of the following is true regarding medullary carcinoma of the thyroid?

Elevated levels of serum calcitonin. **Explanation:** **Medullary Thyroid Carcinoma (MTC)** arises from the **parafollicular C-cells** of the thyroid, which are neuroendocrine cells derived from the neural crest. These cells are responsible for the secretion of **calcitonin**. Therefore, elevated serum calcitonin is a highly sensitive and specific tumor marker for the diagnosis, screening, and monitoring of recurrence in MTC. **Analysis of Options:** * **Option A (Incorrect):** MTC is strongly associated with mutations in the **RET proto-oncogene**, not the MET oncogene. MET is more commonly associated with papillary renal cell carcinoma. * **Option C (Incorrect):** MTC is a component of **MEN 2A and 2B** syndromes. MEN 1 (Wermer’s Syndrome) typically involves the "3 Ps": Pituitary, Parathyroid, and Pancreatic tumors. * **Option D (Incorrect):** **Papillary Thyroid Carcinoma** is the most common type of thyroid cancer (approx. 80-85%). MTC accounts for only about 5-10% of cases. **High-Yield Clinical Pearls for NEET-PG:** 1. **Amyloid Stroma:** Histologically, MTC is characterized by nests of cells separated by an amyloid stroma (stained by Congo Red). 2. **Genetics:** 75% of cases are sporadic; 25% are familial (MEN 2A, 2B, or Familial MTC). 3. **Prophylactic Surgery:** In patients with known RET mutations, prophylactic total thyroidectomy is recommended. 4. **Carcinoembryonic Antigen (CEA):** This is another important tumor marker used alongside calcitonin for MTC. 5. **Spread:** Unlike papillary cancer (lymphatic), MTC spreads via both lymphatic and hematogenous routes.

Q: Carcinoma arising in a thyroglossal cyst is most commonly which type?

Papillary. **Explanation:** Carcinoma arising in a thyroglossal duct cyst (TGDC) is a rare occurrence, seen in less than 1% of cases. The correct answer is **Papillary Carcinoma**, which accounts for approximately **75–85%** of these malignancies. **1. Why Papillary Carcinoma is correct:** The thyroglossal duct is formed by the descent of the thyroid primordium from the foramen cecum. Ectopic thyroid tissue is frequently found within the wall of the cyst. Since papillary carcinoma is the most common type of primary thyroid cancer and arises from follicular cells, it is also the most frequent malignancy found in the ectopic thyroid tissue of a TGDC. **2. Why other options are incorrect:** * **Follicular Carcinoma:** While it arises from follicular cells, it is much less common than papillary carcinoma in both the thyroid gland and TGDCs (approx. 5%). * **Medullary Carcinoma:** This arises from **Parafollicular C-cells** (derived from the ultimobranchial body). Since C-cells do not typically migrate with the thyroglossal duct, medullary carcinoma is almost never found in a TGDC. * **Anaplastic Carcinoma:** This is an undifferentiated, highly aggressive tumor that is extremely rare in the context of a thyroglossal cyst. **High-Yield Pearls for NEET-PG:** * **Most common location of TGDC:** Subhyoid (65%). * **Surgical Treatment:** The **Sistrunk Procedure** (excision of the cyst, the tract, and the central portion of the hyoid bone). * **Diagnostic Clue:** A midline neck swelling that moves upward on **protrusion of the tongue** and on deglutition. * **Management of TGDC Carcinoma:** If the thyroid gland is normal on imaging, a Sistrunk procedure is often sufficient; however, total thyroidectomy is considered if there are suspicious nodules in the main gland or cervical lymphadenopathy.

Question 1

What is the standard treatment for medullary carcinoma of the thyroid?

Accepted Answer

Total thyroidectomy and prophylactic central neck dissection

Answer

Total thyroidectomy only

Answer

Total thyroidectomy and radical neck dissection

Answer

Total thyroidectomy and radioactive iodine therapy

Question 2

Which of the following is the most common histologic type of thyroid cancer?

Accepted Answer

Papillary type

Answer

Anaplastic type

Answer

Medullary type

Answer

Follicular type

Question 3

What is the therapy of choice for diffuse toxic goiter in a patient over 45 years of age?

Accepted Answer

Radioactive iodine

Answer

Surgery

Answer

Antithyroid drugs

Answer

Antithyroid drugs first followed by surgery

Question 4

In the case of hyperthyroidism, which is the most common nerve to be damaged?

Accepted Answer

Recurrent laryngeal nerve

Answer

Inferior laryngeal nerve

Answer

External branch of Superior laryngeal nerve

Answer

Internal branch of Superior laryngeal nerve

Question 5

What is the typical thyroid status in patients with thyroid carcinoma?

Accepted Answer

Usually euthyroid

Answer

Often associated with hypothyroidism

Answer

Often produces hyperthyroidism

Answer

Occurs in toxic nodules

Question 6

Which of the following statements about anaplastic carcinoma of the thyroid is false?

Accepted Answer

It is highly chemosensitive.

Answer

It is characterized by local infiltration.

Answer

Surgery has limited value in its management.

Answer

It spreads via the lymphatic route.

Question 7

Which type of thyroid carcinoma commonly presents with blood-borne metastasis?

Accepted Answer

Follicular

Answer

Papillary

Answer

Mixed

Answer

Medullary

Question 8

Which of the following is true regarding medullary carcinoma of the thyroid?

Accepted Answer

Elevated levels of serum calcitonin

Answer

Associated with the MET oncogene

Answer

Seen in MEN I syndrome

Answer

Most common type of thyroid cancer

Question 9

A patient undergoes thyroid surgery, following which he develops perioral tingling. His blood calcium level is 8.9 meq. What is the next best step?

Accepted Answer

Administer intravenous calcium gluconate and monitor calcium levels serially.

Answer

Administer Vitamin D orally.

Answer

Administer oral calcium and Vitamin D.

Answer

Wait for serum calcium to decrease to less than 7.0 meq before initiating further action.

Question 10

Carcinoma arising in a thyroglossal cyst is most commonly which type?

Accepted Answer

Papillary

Answer

Follicular

Answer

Medullary

Answer

Anaplastic

Endocrine Surgery — MCQs

Endocrine Surgery — MCQs

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