Endocrine Surgery — MCQs

Endocrine Surgery Indian Medical PG Practice Questions and MCQs

Question 31: Which of the following is true regarding parathyroid glands, except?

A. The superior parathyroid glands are located dorsal to the recurrent laryngeal nerve (RLN).
B. The inferior parathyroid glands are located ventral to the recurrent laryngeal nerve (RLN).
C. The blood supply to the parathyroid glands comes from both the superior and inferior thyroid arteries.
D. The superior parathyroid glands lie at the level of the upper border of the thyroid cartilage. (Correct Answer)

Explanation: ### Explanation This question tests the anatomical relationship and embryology of the parathyroid glands, a high-yield topic for NEET-PG. **1. Why Option D is the Correct Answer (The False Statement):** The **superior parathyroid glands** (derived from the 4th branchial pouch) are relatively constant in position. They are typically located at the level of the **cricoid cartilage** or the middle third of the posterior border of the thyroid gland, approximately 1 cm above the intersection of the recurrent laryngeal nerve (RLN) and the inferior thyroid artery. The **upper border of the thyroid cartilage** is too high for their normal anatomical position. **2. Analysis of Other Options:** * **Option A & B (Relationship to RLN):** This is a classic surgical landmark. The **superior** parathyroids (4th pouch) are located **dorsal (posterior)** to the RLN. The **inferior** parathyroids (3rd pouch) are located **ventral (anterior)** to the RLN. A helpful mnemonic is: *"Superior is Posterior, Inferior is Anterior."* * **Option C (Blood Supply):** Both glands primarily receive their blood supply from the **inferior thyroid artery** (80% of cases). However, they can also receive collateral supply from the superior thyroid artery, the thyroid ima artery, or vessels of the esophagus and pharynx. **Clinical Pearls for NEET-PG:** * **Embryology:** The **inferior** parathyroids (3rd pouch) migrate a longer distance alongside the thymus, making them more prone to **ectopic locations** (e.g., mediastinum, carotid sheath). * **Number:** 80% of people have 4 glands; supernumerary glands (5 or more) are found in about 13% of the population. * **Surgical Landmark:** During thyroidectomy, the RLN is the most important structure to identify to avoid vocal cord paralysis; its relationship to the parathyroids helps in their preservation.

Question 32: Which is the best treatment for the management of malignant pheochromocytoma?

A. Alpha blockers
B. Chemotherapy
C. Bulk reducing surgery
D. I131-MIBG (Correct Answer)

Explanation: **Explanation:** The management of **malignant pheochromocytoma** is challenging because malignancy is defined only by the presence of metastases in non-chromaffin tissues (e.g., bone, liver, lungs), not by histology. **Why I131-MIBG is the best treatment:** Metaiodobenzoguanidine (MIBG) is a compound structurally similar to norepinephrine, which is actively taken up by chromaffin cells via the norepinephrine transporter. When tagged with **Iodine-131**, it delivers targeted radiotherapy directly to metastatic sites. It is considered the most effective systemic therapy for symptomatic, unresectable, or widespread malignant disease, offering both symptomatic relief and tumor stabilization. **Analysis of Incorrect Options:** * **Alpha blockers (A):** These are essential for **pre-operative preparation** and symptom control (managing hypertension) but do not treat the underlying malignancy or reduce tumor burden. * **Chemotherapy (B):** The CVD regimen (Cyclophosphamide, Vincristine, and Dacarbazine) is used for rapidly progressing tumors, but response rates are generally lower and more toxic compared to MIBG therapy. * **Bulk reducing surgery (C):** While cytoreductive surgery (debulking) can help reduce catecholamine excess, it is palliative and rarely curative in a malignant setting. It is not the "best" primary treatment for systemic spread. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s:** Pheochromocytoma is 10% bilateral, 10% extra-adrenal, and **10% malignant**. * **Genetic Association:** Malignancy is more common in patients with **SDHB mutations**. * **Diagnosis:** The most sensitive screening test is **Plasma free metanephrines**; the most specific is **24-hour urinary metanephrines**. * **Pre-op Prep:** Always start **Alpha-blockers first** (e.g., Phenoxybenzamine) before Beta-blockers to avoid a hypertensive crisis (unopposed alpha stimulation).

Question 33: Which of the following is NOT a characteristic of medullary carcinoma of the thyroid?

A. Contains amyloid
B. TSH dependent (Correct Answer)
C. Secretes calcitonin
D. Patients should be screened for RET point mutation on chromosome 10

Explanation: ### Explanation **1. Why "TSH dependent" is the correct (False) statement:** Medullary Thyroid Carcinoma (MTC) originates from the **parafollicular C-cells** (neuroendocrine cells) of the thyroid, which are derived from the **ultimobranchial body** (neural crest cells). Unlike papillary and follicular carcinomas, which arise from follicular cells and have TSH receptors, C-cells do not possess TSH receptors. Therefore, MTC is **not TSH-dependent**, and TSH suppression therapy has no role in its management. **2. Analysis of incorrect options:** * **Contains amyloid:** A hallmark histological feature of MTC is the presence of extracellular **amyloid deposits**, which represent pro-calcitonin fibrils. These stain positive with **Congo Red** and show apple-green birefringence under polarized light. * **Secretes calcitonin:** Calcitonin is the primary biomarker for MTC. It is used for diagnosis, monitoring treatment response, and detecting recurrence. Some tumors also secrete CEA (Carcinoembryonic Antigen). * **RET point mutation (Chromosome 10):** Approximately 25% of MTC cases are familial (MEN 2A, 2B, or Familial MTC). These are associated with germline mutations in the **RET proto-oncogene** located on chromosome 10. All patients diagnosed with MTC must be screened for this mutation to guide family screening and prophylactic thyroidectomy. **Clinical Pearls for NEET-PG:** * **Most common site:** Junction of the upper 1/3rd and lower 2/3rds of the thyroid lobe (highest concentration of C-cells). * **Spread:** Early lymphatic spread to central and lateral neck nodes is common. * **MEN 2A:** MTC + Pheochromocytoma + Hyperparathyroidism. * **MEN 2B:** MTC + Pheochromocytoma + Mucosal neuromas + Marfanoid habitus. * **Surgery:** Total thyroidectomy with central compartment neck dissection is the treatment of choice.

Question 34: Which type of thyroid carcinoma is characterized by pulsatile vascular skeletal metastasis?

A. Medullary
B. Anaplastic
C. Follicular (Correct Answer)
D. Papillary

Explanation: **Explanation:** **Follicular Thyroid Carcinoma (FTC)** is the correct answer because of its unique mode of spread. Unlike Papillary carcinoma, which primarily spreads via the lymphatics, FTC spreads **hematogenously** (through the bloodstream). 1. **Why Follicular is Correct:** FTC is a highly vascular tumor. When it metastasizes to the bone (most commonly the skull, ribs, or pelvis), the secondary deposits retain this extreme vascularity. These lesions are typically osteolytic and exhibit **pulsations** due to the high blood flow within the metastatic tissue. A "pulsatile bone swelling" in a patient with a thyroid nodule is a classic clinical sign of FTC. 2. **Why Other Options are Incorrect:** * **Papillary (D):** The most common thyroid cancer; it spreads via **lymphatics** to cervical nodes. Bone metastasis is rare and typically non-pulsatile. * **Medullary (A):** Arises from parafollicular C-cells. While it can spread hematogenously in advanced stages, it is not associated with pulsatile skeletal lesions. It is better known for secreting Calcitonin. * **Anaplastic (B):** A highly aggressive, undifferentiated tumor. It causes rapid local invasion and widespread metastasis, but patients usually succumb to local airway obstruction before specific pulsatile bone lesions become a defining feature. **High-Yield Clinical Pearls for NEET-PG:** * **Hematogenous spread** is the hallmark of FTC (Bones, Lungs, Liver). * **Diagnosis:** FTC cannot be diagnosed by FNCA because FNCA cannot distinguish between a follicular adenoma and carcinoma (requires histological proof of **capsular or vascular invasion**). * **Other causes of pulsatile bone metastasis:** Renal Cell Carcinoma (RCC) is the other major differential diagnosis for pulsatile skeletal secondaries. * **Treatment:** Total thyroidectomy followed by Radioactive Iodine (RAI) ablation is the standard for metastatic FTC.

Question 35: What is the most common life-threatening complication of thyroidectomy?

A. Haemorrhage (Correct Answer)
B. Tracheal collapse
C. Laryngeal edema
D. Bilateral vocal cord palsy

Explanation: **Explanation:** The most common life-threatening complication following thyroidectomy is **post-operative haemorrhage** (specifically, a tension haematoma). 1. **Why Haemorrhage is Correct:** While rare (occurring in ~1-2% of cases), a bleed into the tight subplatysmal space leads to a rapid buildup of pressure. This does not cause death by simple blood loss, but by **mechanical compression of the airway** and venous congestion leading to laryngeal edema. It is a surgical emergency requiring immediate bedside decompression (opening the sutures) to restore the airway. 2. **Why Other Options are Incorrect:** * **Tracheal Collapse (Tracheomalacia):** This occurs due to long-standing pressure from a large goiter softening the tracheal rings. While life-threatening, it is significantly less common than post-operative bleeding in modern surgical practice. * **Laryngeal Edema:** This is often a *secondary* result of venous obstruction caused by a haematoma or trauma from intubation, rather than the primary life-threatening event itself. * **Bilateral Vocal Cord Palsy:** Caused by bilateral Recurrent Laryngeal Nerve (RLN) injury. While it causes acute airway obstruction (stridor) requiring tracheostomy, its incidence is much lower than haemorrhage due to improved nerve monitoring and surgical techniques. **Clinical Pearls for NEET-PG:** * **Most common complication overall:** Hypocalcaemia (transient). * **Most common nerve injured:** External branch of the Superior Laryngeal Nerve (leads to loss of high-pitched voice). * **Timing:** Post-thyroidectomy haemorrhage typically occurs within the first **6 to 24 hours**. * **Management:** The immediate step for a post-op patient with respiratory distress and neck swelling is **opening the wound at the bedside**, not waiting for an OR or intubation.

Question 36: Which of the following statements about hyperparathyroidism is FALSE?

A. It commonly occurs after thyroidectomy. (Correct Answer)
B. It may cause hypercalcemia.
C. Solitary adenoma is the most common cause.
D. None of the above.

Explanation: **Explanation:** **1. Why Option A is the Correct (False) Statement:** Hyperparathyroidism refers to the **overactivity** of the parathyroid glands. Thyroidectomy is a common cause of **hypoparathyroidism**, not hyperparathyroidism. During thyroid surgery, the parathyroid glands may be inadvertently removed, devascularized, or traumatized, leading to a deficiency in Parathyroid Hormone (PTH) and subsequent hypocalcemia. Therefore, stating that hyperparathyroidism commonly occurs after thyroidectomy is medically incorrect. **2. Analysis of Incorrect Options:** * **Option B (It may cause hypercalcemia):** This is a **true** statement. PTH increases bone resorption, renal calcium reabsorption, and intestinal calcium absorption (via Vitamin D). Excess PTH directly leads to elevated serum calcium levels. * **Option C (Solitary adenoma is the most common cause):** This is a **true** statement. Approximately 80–85% of primary hyperparathyroidism cases are caused by a single benign adenoma. Other causes include gland hyperplasia (15%) and rare parathyroid carcinoma (<1%). **3. High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** Often described by the mnemonic "Bones, Stones, Abdominal Groans, and Psychic Moans" (osteitis fibrosa cystica, nephrolithiasis, peptic ulcers/pancreatitis, and depression/confusion). * **Biochemical Hallmark:** Elevated Serum Calcium + Elevated/Inappropriately Normal PTH + Low Serum Phosphate. * **Localization:** Sestamibi scan (Technetium-99m) is the gold standard for preoperative localization of an adenoma. * **Hungry Bone Syndrome:** A common postoperative complication after parathyroidectomy where rapid bone remineralization leads to severe hypocalcemia.

Question 37: Which type of thyroid cancer is considered the least malignant?

A. Papillary carcinoma (Correct Answer)
B. Follicular carcinoma
C. Medullary carcinoma
D. Anaplastic carcinoma

Explanation: **Explanation:** Thyroid carcinomas exhibit a wide spectrum of biological behavior, ranging from indolent to highly aggressive. **Papillary Thyroid Carcinoma (PTC)** is the most common thyroid malignancy (80-85%) and is considered the **least malignant** because it is slow-growing, well-differentiated, and has an excellent 10-year survival rate (often >95%). While it frequently spreads via lymphatics to cervical nodes, this does not significantly worsen the overall prognosis in younger patients. **Analysis of Options:** * **A. Papillary Carcinoma (Correct):** It has the best prognosis. Key features include Orphan Annie eye nuclei, Psammoma bodies, and a strong association with ionizing radiation. * **B. Follicular Carcinoma:** More aggressive than PTC. It spreads hematogenously (to bone and lungs) rather than lymphatically. It is associated with iodine deficiency. * **C. Medullary Carcinoma:** Arises from parafollicular C-cells (secretes Calcitonin). It is more aggressive than well-differentiated cancers and can be part of MEN 2A/2B syndromes. * **D. Anaplastic Carcinoma:** The most aggressive/malignant form. It is undifferentiated, grows rapidly, causes early local invasion (airway obstruction), and is almost always fatal within months. **High-Yield Clinical Pearls for NEET-PG:** * **Prognosis Order (Best to Worst):** Papillary > Follicular > Medullary > Anaplastic. * **Psammoma Bodies:** Characteristic of Papillary carcinoma (concentric calcifications). * **Diagnosis:** PTC and Medullary can be diagnosed via FNAC; Follicular carcinoma **cannot** be diagnosed by FNAC (requires histology to see capsular/vascular invasion). * **Most common site of distant metastasis in PTC:** Lungs.

Question 38: Thyroid carcinoma can cause laryngeal paralysis due to involvement of which nerve?

A. Recurrent laryngeal nerve palsy (Correct Answer)
B. Vagus nerve palsy
C. Glossopharyngeal nerve palsy
D. Hypoglossal nerve palsy

Explanation: ### Explanation **1. Why Recurrent Laryngeal Nerve (RLN) is the Correct Answer:** The thyroid gland is anatomically related to the **Recurrent Laryngeal Nerve (RLN)**, which travels in the tracheoesophageal groove, immediately posterior to the thyroid lobes. In cases of invasive thyroid carcinoma (particularly papillary or anaplastic types), the tumor can directly infiltrate or compress the RLN. Since the RLN provides motor supply to all intrinsic muscles of the larynx (except the cricothyroid), its involvement leads to **vocal cord paralysis**, manifesting clinically as hoarseness of voice or respiratory distress (if bilateral). **2. Why Other Options are Incorrect:** * **Vagus Nerve (CN X):** While the RLN is a branch of the Vagus, the Vagus nerve itself runs within the carotid sheath, lateral to the thyroid. It is rarely involved unless there is extensive lateral neck metastasis or carotid sheath invasion. * **Glossopharyngeal Nerve (CN IX):** This nerve supplies the stylopharyngeus muscle and provides sensation to the posterior third of the tongue. It is located much higher in the neck/skull base and is not anatomically related to the thyroid gland. * **Hypoglossal Nerve (CN XII):** This is the motor nerve for the tongue. It is located superior to the hyoid bone and is not affected by standard thyroid malignancies. **3. NEET-PG High-Yield Clinical Pearls:** * **Most common nerve injured** during thyroidectomy: **External branch of the Superior Laryngeal Nerve (EBSLN)** (causes loss of high-pitched voice). * **Most serious nerve injury** during thyroidectomy: **Recurrent Laryngeal Nerve** (causes hoarseness; bilateral injury causes airway obstruction). * **Nerve of Amelita Galli-Curci:** Another name for the EBSLN. * **Berry’s Ligament:** The RLN is most vulnerable to injury near the Ligament of Berry, where it is in close proximity to the inferior thyroid artery.

Question 39: Which carcinoma does not arise from thyroid follicles?

A. Medullary carcinoma (Correct Answer)
B. Papillary carcinoma
C. Anaplastic carcinoma
D. Hürthle cell carcinoma

Explanation: The thyroid gland contains two distinct types of secretory cells with different embryological origins: **Follicular cells** and **Parafollicular (C) cells**. ### **Why Medullary Carcinoma is the Correct Answer** **Medullary Thyroid Carcinoma (MTC)** arises from the **Parafollicular C-cells**, which are derived from the **ultimobranchial body** (neural crest origin). These cells are responsible for secreting **Calcitonin**. Because MTC does not arise from follicular cells, it does not concentrate iodine and cannot be treated with Radioiodine (RAI) therapy. ### **Analysis of Incorrect Options** * **Papillary Carcinoma (B):** The most common thyroid malignancy; it arises directly from the thyroid follicular epithelium. * **Anaplastic Carcinoma (C):** An undifferentiated, highly aggressive tumor that arises from follicular cells, often via the dedifferentiation of a pre-existing well-differentiated carcinoma. * **Hürthle Cell Carcinoma (D):** A variant of follicular carcinoma characterized by oxyphilic cells (Askanazy cells). These are modified follicular cells packed with mitochondria. ### **NEET-PG High-Yield Pearls** * **Origin:** Follicular cells are endodermal; C-cells are neuroendocrine (neural crest). * **Tumor Markers:** * Papillary/Follicular: **Thyroglobulin**. * Medullary: **Calcitonin** (for diagnosis/follow-up) and **CEA** (for prognosis). * **Genetics:** MTC is associated with **RET proto-oncogene** mutations and occurs in **MEN 2A and 2B** syndromes. * **Amyloid Staining:** MTC is histologically characterized by **amyloid stroma** (stained with Congo Red), which represents pro-calcitonin deposits.

Question 40: A 20-year-old patient with hypertension has been diagnosed as a case of pheochromocytoma with positive biochemical evidence. What is the next step in the workup of this patient?

A. MRI Abdomen (Correct Answer)
B. Perform urinary VMA levels
C. Perform adrenal vein sampling
D. MIBG scintigraphy

Explanation: In the management of pheochromocytoma, the diagnostic sequence is critical: **Biochemical confirmation must always precede radiological localization.** ### 1. Why MRI Abdomen is Correct Once biochemical evidence (elevated plasma or urinary metanephrines) confirms the diagnosis, the next step is anatomical localization. **CT or MRI of the abdomen and pelvis** is the initial imaging modality of choice because >95% of these tumors are located in the adrenal glands or the organ of Zuckerkandl. * **MRI is often preferred over CT** in young patients (to avoid radiation), pregnant women, or those with contrast allergies. * MRI has high sensitivity (90-100%) and shows a characteristic **"Light Bulb" appearance** (hyperintensity) on T2-weighted images. ### 2. Why Other Options are Incorrect * **B. Urinary VMA levels:** This is a biochemical test used for screening/diagnosis. Since the question states biochemical evidence is already positive, repeating this is redundant. Note: VMA has lower sensitivity than metanephrines. * **C. Adrenal vein sampling:** This is used in primary hyperaldosteronism (Conn’s syndrome) to lateralize the source of aldosterone. It is not indicated in pheochromocytoma and can trigger a hypertensive crisis. * **D. MIBG Scintigraphy:** This is a **functional imaging** technique. It is indicated only if CT/MRI is negative, or if there is suspicion of extra-adrenal (paraganglioma), metastatic, or multifocal disease. It is not the *initial* imaging step. ### 3. Clinical Pearls for NEET-PG * **Rule of 10s:** 10% are bilateral, 10% are extra-adrenal, 10% are malignant, and 10% are familial. * **Pre-op Management:** Always start **Alpha-blockers first** (e.g., Phenoxybenzamine) for 10-14 days, followed by Beta-blockers to prevent a hypertensive crisis. * **Genetic Screening:** All patients with pheochromocytoma should be screened for germline mutations (MEN2, VHL, NF1, SDH mutations).

Practice by Chapter

Thyroid Nodules

Practice Questions

Thyroid Cancer

Practice Questions

Graves' Disease

Practice Questions

Thyroiditis

Practice Questions

Primary Hyperparathyroidism

Practice Questions

Secondary and Tertiary Hyperparathyroidism

Practice Questions

Adrenal Cortical Tumors

Practice Questions

Pheochromocytoma

Practice Questions

Adrenal Incidentalomas

Practice Questions

Multiple Endocrine Neoplasia

Practice Questions

Neuroendocrine Tumors

Practice Questions

Intraoperative Monitoring in Endocrine Surgery

Practice Questions

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