Endocrine Surgery Practice Questions

Q: What is the most common type of thyroid carcinoma?

Papillary. **Explanation:** Thyroid carcinomas are classified based on their histological origin. **Papillary Thyroid Carcinoma (PTC)** is the most common type, accounting for approximately **80–85%** of all thyroid malignancies. It typically presents as a slow-growing, painless thyroid nodule and has an excellent prognosis. It is associated with radiation exposure and specific genetic mutations like **BRAF** and **RET/PTC** rearrangements. **Analysis of Options:** * **A. Papillary (Correct):** It is the most frequent thyroid cancer. Key histological features include **Orphan Annie eye nuclei** (clear nuclei), **Psammoma bodies** (calcifications), and nuclear grooves. It spreads primarily via the **lymphatics**. * **B. Follicular:** The second most common type (approx. 10%). Unlike PTC, it spreads **hematogenously** (to lungs/bones) and is more common in iodine-deficient areas. * **C. Medullary:** Accounts for about 5% of cases. It arises from **Parafollicular C-cells** and secretes **Calcitonin**. It can be sporadic or part of MEN 2A/2B syndromes. * **D. Anaplastic:** Rare (<2%) but highly aggressive. It has the worst prognosis among thyroid cancers, often presenting in elderly patients with rapid local invasion. **High-Yield Clinical Pearls for NEET-PG:** * **Most common thyroid cancer:** Papillary. * **Most common thyroid cancer in children:** Papillary. * **Most common thyroid cancer post-radiation:** Papillary. * **Route of spread:** Papillary = Lymphatic; Follicular = Hematogenous. * **Diagnosis:** FNAC can diagnose Papillary, Medullary, and Anaplastic, but **cannot** distinguish between Follicular Adenoma and Carcinoma (requires biopsy to see capsular/vascular invasion).

Q: Which metastatic sites are most common to the thyroid gland?

Lung. **Explanation:** Metastasis to the thyroid gland is an infrequent clinical finding but is increasingly identified in autopsy series. Among non-thyroidal primary malignancies, the **Lung** is the most common site of origin for thyroid metastases, followed closely by the kidney (Renal Cell Carcinoma) and the breast. * **Lung (Correct):** Large-scale autopsy studies consistently identify lung cancer as the most frequent primary source. This is attributed to the high incidence of lung cancer and its propensity for hematogenous spread. In clinical practice (symptomatic patients), Renal Cell Carcinoma is often the most common, but for the NEET-PG context, Lung is the established answer for overall frequency. * **Breast:** While breast cancer is a common source of metastasis to various organs, it typically ranks second or third behind lung and kidney in its frequency of spread to the thyroid. * **Brain:** Primary brain tumors rarely metastasize outside the central nervous system. Conversely, the thyroid frequently metastasizes *to* the brain (especially papillary and follicular types), but the reverse is not true. * **Gastrointestinal Tract:** While cancers of the colon or stomach can metastasize to the thyroid, they are significantly less common than thoracic or renal primaries. **High-Yield Clinical Pearls for NEET-PG:** * **Most common clinical presentation:** A rapidly enlarging, firm, painless thyroid mass in a patient with a known history of malignancy. * **Renal Cell Carcinoma (RCC):** Often presents with the longest latency period (metastasis may appear years after the primary tumor is treated). * **Diagnosis:** Fine Needle Aspiration Cytology (FNAC) is the gold standard, often requiring immunohistochemistry (IHC) to differentiate from primary thyroid medullary or anaplastic carcinoma. * **Prognosis:** Generally poor, as thyroid involvement usually signifies disseminated systemic disease.

Q: What is the most common hormone, other than gastrin, found in a gastric secreting islet cell tumor?

ACTH. **Explanation:** Gastrinomas (Zollinger-Ellison Syndrome) are the most common functional pancreatic neuroendocrine tumors (pNETs). While they primarily secrete gastrin, they are frequently **multihormonal**. **1. Why ACTH is the correct answer:** Studies and clinical pathology reports indicate that **ACTH (Adrenocorticotropic Hormone)** is the most common secondary hormone produced by gastrin-secreting islet cell tumors. When a gastrinoma secretes ACTH, it can lead to ectopic Cushing syndrome, which is often a marker of a more aggressive or metastatic tumor. This association is particularly important in the context of **MEN-1 (Multiple Endocrine Neoplasia Type 1)**, where multiple tumors may coexist. **2. Why other options are incorrect:** * **B. Glucagon:** While glucagonomas exist, they are distinct clinical entities (presenting with necrolytic migratory erythema). Glucagon is less frequently co-secreted by gastrinomas compared to ACTH. * **C. Growth hormone-releasing factor (GHRF):** GHRF secretion from a pNET can cause acromegaly, but this is a rare occurrence compared to the frequency of ACTH co-secretion. * **D. Insulin:** Insulinomas are usually solitary and do not typically co-secrete gastrin. If a patient has both high insulin and high gastrin, it usually suggests two separate tumors (common in MEN-1) rather than a single tumor secreting both. **High-Yield Pearls for NEET-PG:** * **Passaro’s Triangle (Gastrinoma Triangle):** The anatomical area where 90% of gastrinomas are found (bounded by the cystic duct, junction of the 2nd and 3rd parts of the duodenum, and the neck of the pancreas). * **Most common site:** The **duodenum** is now recognized as the most common site for gastrinomas, especially in MEN-1. * **Malignancy:** Approximately 60-90% of gastrinomas are malignant. * **Clinical Hint:** If a gastrinoma patient presents with hypokalemia and hypercortisolism, suspect ectopic **ACTH** production.

Q: A 57-year-old female underwent a total thyroidectomy. Following the surgery, she developed stridor and dyspnea. What is the most likely cause?

Bilateral recurrent laryngeal nerve injury. **Explanation:** The development of acute **stridor and dyspnea** immediately following a total thyroidectomy is a surgical emergency, most commonly caused by **Bilateral Recurrent Laryngeal Nerve (RLN) injury**. **1. Why Option C is Correct:** The RLN supplies all the intrinsic muscles of the larynx except the cricothyroid. Its primary function is to **abduct** (open) the vocal cords via the posterior cricoarytenoid muscle. In a bilateral injury, both vocal cords assume a **paramedian position**. This significantly narrows the glottic aperture, leading to acute airway obstruction, inspiratory stridor, and respiratory distress, often necessitating an emergency tracheostomy. **2. Why Other Options are Incorrect:** * **Unilateral RLN injury (Option D):** This typically presents with **hoarseness of voice** or a weak cough. Because the unaffected vocal cord can still abduct, the airway remains patent, and stridor does not occur. * **Superior Laryngeal Nerve (SLN) injury (Options A & B):** The SLN (external branch) supplies the cricothyroid muscle, which tenses the vocal cords. Injury leads to a loss of high-pitched voice and vocal fatigue (the "monotone voice"), but it **never** causes airway obstruction or stridor. **Clinical Pearls for NEET-PG:** * **Most common cause of post-thyroidectomy stridor:** While bilateral RLN injury is the most common *nerve* cause, **Tension Hematoma** (compressive) is the most common *overall* cause in the immediate postoperative period. * **Nerve Vulnerability:** The RLN is most commonly injured at the **Ligament of Berry**. * **Management:** If stridor occurs due to a hematoma, the immediate step is to **open the wound sutures at the bedside** to decompress the airway. If due to bilateral RLN injury, re-intubation or tracheostomy is required.

Q: After thyroidectomy, a patient developed stridor within 2 hours. What is the most likely cause of stridor in this patient?

Recurrent laryngeal nerve palsy. **Explanation:** The development of stridor within the immediate post-operative period (0–2 hours) after thyroidectomy is a surgical emergency. **1. Why Recurrent Laryngeal Nerve (RLN) Palsy is Correct:** The RLN supplies all intrinsic muscles of the larynx except the cricothyroid. **Bilateral RLN injury** results in both vocal cords assuming a paramedian position, narrowing the glottic opening significantly. This leads to acute airway obstruction and **inspiratory stridor** immediately upon extubation or shortly thereafter. While unilateral injury causes hoarseness, bilateral injury is a classic cause of post-thyroidectomy respiratory distress. **2. Why the other options are incorrect:** * **Hypocalcemia (Option A):** While hypocalcemia can cause laryngospasm and stridor (tetany), it typically manifests **24 to 72 hours** post-surgery as the serum calcium levels drop. It is unlikely to occur within the first 2 hours. * **Carotid Artery/Jugular Vein Injury (Options C & D):** While injury to these vessels can cause a **tension hematoma**, the primary mechanism of stridor in that scenario is external compression of the trachea, not the vascular injury itself. If "Hematoma" were an option, it would be a strong differential, but the vessels themselves do not cause stridor. **NEET-PG High-Yield Pearls:** * **Most common cause of stridor <2 hours:** 1. Tension Hematoma (most common overall), 2. Bilateral RLN palsy. * **Management of Post-op Hematoma:** Immediate bedside opening of the wound (evacuation of clots) to decompress the trachea, followed by surgery. * **Tracheomalacia:** Occurs in patients with long-standing large goiters where the tracheal rings have weakened; stridor occurs due to tracheal collapse upon extubation. * **Nerve Monitoring:** Intraoperative nerve monitoring (IONM) is used to identify and preserve the RLN during dissection.

Q: Which of the following will not lead to respiratory distress after thyroid surgery?

None of the above. **Explanation:** Respiratory distress is a critical postoperative complication of thyroid surgery. The correct answer is **None of the above** because all three listed conditions (A, B, and C) are recognized causes of airway compromise following thyroidectomy. 1. **Laryngomalacia (Tracheomalacia):** Long-standing, large goiters can cause pressure necrosis and softening of the tracheal rings (tracheomalacia). When the thyroid is removed, the structural support for the trachea is lost, leading to tracheal collapse during inspiration, resulting in acute respiratory distress. 2. **Bilateral Recurrent Laryngeal Nerve (RLN) Injury:** While unilateral injury causes hoarseness, bilateral injury results in both vocal cords assuming a paramedian position. This narrows the glottic chink significantly, causing immediate postoperative stridor and airway obstruction. 3. **Hypocalcemia:** Accidental removal or devascularization of the parathyroid glands leads to hypocalcemia. Severe hypocalcemia increases neuromuscular irritability, which can manifest as **laryngospasm**, leading to acute respiratory distress (typically 24–72 hours post-op). **Clinical Pearls for NEET-PG:** * **Most common cause** of respiratory distress in the first 24 hours is a **tension hematoma** (reactionary hemorrhage). The immediate management is bedside evacuation of the clot by opening the wound. * **Laryngeal Edema:** Often caused by traumatic intubation or venous/lymphatic obstruction; managed with steroids or re-intubation. * **Bilateral RLN injury** requires immediate tracheostomy or re-intubation. * **Chvostek’s and Trousseau’s signs** are classic clinical indicators of the hypocalcemia that leads to the aforementioned laryngospasm.

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.

Question 1

What is the most common type of thyroid carcinoma?

Accepted Answer

Papillary

Answer

Follicular

Answer

Medullary

Answer

Anaplastic

Question 2

Which metastatic sites are most common to the thyroid gland?

Accepted Answer

Lung

Answer

Breast

Answer

Brain

Answer

Gastrointestinal tract

Question 3

What is the most common hormone, other than gastrin, found in a gastric secreting islet cell tumor?

Accepted Answer

ACTH

Answer

Glucagon

Answer

Growth hormone releasing factor

Answer

Insulin

Question 4

A 57-year-old female underwent a total thyroidectomy. Following the surgery, she developed stridor and dyspnea. What is the most likely cause?

Accepted Answer

Bilateral recurrent laryngeal nerve injury

Answer

Bilateral superior laryngeal nerve injury

Answer

Unilateral superior laryngeal nerve injury

Answer

Unilateral recurrent laryngeal nerve injury

Question 5

After thyroidectomy, a patient developed stridor within 2 hours. What is the most likely cause of stridor in this patient?

Accepted Answer

Recurrent laryngeal nerve palsy

Answer

Hypocalcemia

Answer

Carotid artery injury

Answer

Jugular vein injury

Question 6

A 26-year-old woman presents with a palpable thyroid nodule. Needle biopsy demonstrates amyloid in the stroma of the lesion. A cervical lymph node is palpable on the same side as the lesion. What is the preferred treatment?

Accepted Answer

Total thyroidectomy and modified neck dissection on the side of the enlarged lymph node.

Answer

Removal of the involved node, the isthmus, and the enlarged lymph node.

Answer

Removal of the involved lobe, the isthmus, a portion of the opposite lobe, and the enlarged lymph node.

Answer

Total thyroidectomy and irradiation of the cervical lymph nodes.

Question 7

Which of the following will not lead to respiratory distress after thyroid surgery?

Accepted Answer

None of the above

Answer

Laryngomalacia

Answer

Bilateral recurrent laryngeal nerve injury

Answer

Hypocalcemia

Question 8

Which of the following statements about papillary carcinoma of the thyroid are true?

Accepted Answer

Radiation is a risk factor, Multifocal, Distant metastasis is seen, and Most common in iodine deficient areas.

Answer

Radiation is a risk factor, Multifocal, Hematogenous spread is common, and Distant metastasis is seen.

Answer

Multifocal, Hematogenous spread is common, Distant metastasis is seen, and Most common in iodine deficient areas.

Answer

All statements are true.

Question 9

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 10

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

Endocrine Surgery — MCQs

Endocrine Surgery — MCQs

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