Endocrine Surgery — MCQs

Endocrine Surgery Indian Medical PG Practice Questions and MCQs

Question 161: In pheochromocytoma, which of the following is NOT part of the 'rule of 10'?

A. 10% are bilateral
B. 10% are malignant
C. 10% are extra-adrenal
D. 10% are symptomatic (Correct Answer)

Explanation: ### Explanation Pheochromocytoma is a catecholamine-secreting tumor arising from chromaffin cells of the adrenal medulla. Traditionally, it is described by the **"Rule of 10s,"** which helps clinicians remember its epidemiological distribution. **Why Option D is the correct answer:** The statement "10% are symptomatic" is **incorrect** because the vast majority of patients with pheochromocytoma are symptomatic. The classic triad consists of episodic headache, sweating (diaphoresis), and palpitations, often accompanied by hypertension. If only 10% were symptomatic, the tumor would rarely be diagnosed clinically. **Analysis of the "Rule of 10s" (Incorrect Options):** * **10% are Bilateral (Option A):** Most cases are sporadic and unilateral; however, roughly 10% occur on both sides (this percentage is significantly higher in familial syndromes like MEN 2A/2B). * **10% are Malignant (Option B):** About 90% are benign. Malignancy is defined not by histology, but by the presence of tumor cells in non-chromaffin sites (e.g., bone, liver, lungs). * **10% are Extra-adrenal (Option C):** These are known as **paragangliomas**. The most common extra-adrenal site is the Organ of Zuckerkandl (near the origin of the inferior mesenteric artery). **High-Yield Clinical Pearls for NEET-PG:** 1. **Rule of 10s Update:** Recent genetics suggest that up to **30-40%** of cases may be hereditary (associated with *RET, VHL, NF1,* and *SDH* mutations), challenging the traditional "10% familial" rule. 2. **Diagnosis:** The best initial screening test is **24-hour urinary fractionated metanephrines** or plasma free metanephrines. 3. **Pre-operative Management:** Always follow the rule: **Alpha-blockade first** (e.g., Phenoxybenzamine) for 10-14 days, followed by Beta-blockade to prevent a hypertensive crisis. 4. **10% occur in children.**

Question 162: Persistent multinodular goiter may cause which of the following complications?

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

Explanation: **Explanation:** The correct answer is **Follicular Carcinoma (Option A)**. **Underlying Concept:** Long-standing or persistent Multinodular Goiter (MNG) is a known risk factor for the development of Follicular Thyroid Carcinoma (FTC). This association is primarily linked to areas of **endemic iodine deficiency**, where chronic stimulation by Thyroid Stimulating Hormone (TSH) leads to follicular hyperplasia. Over time, this persistent proliferative stress can result in malignant transformation into follicular carcinoma. While most MNGs are benign, any dominant or rapidly growing nodule within a long-standing goiter must be evaluated for malignancy. **Analysis of Incorrect Options:** * **B. Papillary Carcinoma:** This is the most common thyroid malignancy overall. Its primary risk factor is **ionizing radiation** exposure, not long-standing MNG. It is more common in iodine-sufficient areas. * **C. Medullary Carcinoma:** This arises from the **parafollicular C-cells** (neuroendocrine origin) and is often associated with genetic mutations (RET proto-oncogene) or MEN 2 syndromes. It has no etiologic link to MNG. * **D. Colloid Carcinoma:** This is not a standard primary thyroid malignancy; "colloid" typically refers to the benign storage material found within thyroid follicles in a goiter. **High-Yield Clinical Pearls for NEET-PG:** * **Iodine Status:** FTC is more common in iodine-deficient areas; Papillary carcinoma is more common in iodine-rich areas. * **Diagnosis:** FTC cannot be diagnosed by FNAC alone because FNAC cannot distinguish between a follicular adenoma and carcinoma. Diagnosis requires histological evidence of **capsular or vascular invasion**. * **Spread:** FTC typically spreads **hematogenously** (to lungs and bone), whereas Papillary carcinoma spreads via **lymphatics**. * **Anaplastic Carcinoma:** Long-standing MNG is also a significant risk factor for Anaplastic carcinoma in elderly patients.

Question 163: What is the most common cause of a solitary thyroid nodule?

A. Physiological goitre
B. Follicular adenoma (Correct Answer)
C. Colloid degeneration
D. Cysts

Explanation: ### Explanation The correct answer is **Follicular adenoma**. **1. Why Follicular Adenoma is Correct:** A solitary thyroid nodule (STN) is defined clinically as a localized thyroid enlargement in an otherwise normal-feeling gland. While the majority of thyroid swellings are multinodular goitres (MNG), when a **true solitary nodule** is encountered, the most common **benign neoplasm** and overall cause is a **Follicular Adenoma**. It is a true encapsulated lesion. In clinical practice, while a "dominant nodule" of a multinodular goitre is common, the classical textbook answer for the most common pathological cause of a solitary nodule remains follicular adenoma. **2. Analysis of Incorrect Options:** * **Physiological Goitre (A):** This typically presents as a smooth, diffuse enlargement of the thyroid gland (diffuse hyperplastic goitre) during periods of high iodine demand (puberty/pregnancy), rather than a discrete solitary nodule. * **Colloid Degeneration (C):** Colloid nodules are very common, but they are usually part of a Multinodular Goitre (MNG). A "dominant" colloid nodule may mimic an STN, but pathologically, it is a feature of MNG rather than the primary cause of a solitary neoplastic nodule. * **Cysts (D):** Most thyroid cysts are actually "pseudocysts" resulting from the degeneration of a follicular adenoma or a colloid nodule. Pure epithelial cysts are rare. **3. NEET-PG Clinical Pearls:** * **The Rule of 12:** Approximately 12% of solitary thyroid nodules are malignant (Papillary carcinoma being the most common malignancy). * **Investigation of Choice:** **FNAC** (Fine Needle Aspiration Cytology) is the gold standard for initial evaluation. * **FNAC Limitation:** FNAC **cannot** distinguish between a Follicular Adenoma and a Follicular Carcinoma because it cannot assess capsular or vascular invasion. Histopathology is required for this distinction. * **Hot vs. Cold:** On radionuclide scanning, most STNs are "cold" (non-functional). Cold nodules have a higher risk of malignancy compared to "hot" nodules.

Question 164: In which of the following thyroid malignancies does the size of the primary lesion have a greater impact on prognosis than lymph node metastasis?

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

Explanation: **Explanation:** In **Papillary Thyroid Carcinoma (PTC)**, the most common thyroid malignancy, the presence of regional lymph node metastasis is frequent (occurring in up to 50-80% of cases) but surprisingly has a **minimal impact on overall survival**, especially in younger patients. According to the **AMES** (Age, Metastasis, Extent, Size) and **MACIS** scoring systems, the **size of the primary tumor** (>4 cm) and the age of the patient are far more significant prognostic indicators than nodal involvement. While nodal spread increases the risk of local recurrence, it does not significantly decrease long-term survival rates. **Analysis of Incorrect Options:** * **B. Follicular Carcinoma:** This tumor spreads primarily via the **hematogenous route** (bloodstream) rather than lymphatics. Therefore, lymph node metastasis is rare, and prognosis is dictated by vascular invasion and distant metastasis (bone/lung). * **C. Medullary Carcinoma:** Derived from parafollicular C-cells, this tumor is more aggressive than PTC. The presence of lymph node metastasis here is a **strong negative prognostic factor** and significantly correlates with a decrease in survival and higher recurrence rates. * **D. Anaplastic Carcinoma:** This is one of the most lethal human malignancies. The prognosis is universally poor regardless of size or nodal status, as most patients present with locally advanced disease or distant metastasis at the time of diagnosis. **High-Yield Clinical Pearls for NEET-PG:** * **Most common thyroid cancer:** Papillary Carcinoma. * **Characteristic Histology (PTC):** Orphan Annie eye nuclei, Psammoma bodies, and Coffee bean nuclei (nuclear grooves). * **Route of Spread:** Papillary = Lymphatic; Follicular = Hematogenous. * **Prognostic Systems:** Remember **AMES** and **MACIS** for PTC; size and age are the heavy hitters, not nodes.

Question 165: What is the best test to differentiate between benign and malignant thyroid lesions?

A. Fine Needle Aspiration Cytology (FNAC)
B. CT scan
C. Excision biopsy (Correct Answer)
D. MRI

Explanation: **Explanation:** The definitive diagnosis of malignancy in any tissue requires the demonstration of architectural invasion (capsular or vascular invasion). 1. **Why Excision Biopsy is Correct:** In thyroid pathology, particularly for **Follicular Neoplasms**, Fine Needle Aspiration Cytology (FNAC) can identify follicular cells but cannot distinguish between a benign Follicular Adenoma and a malignant Follicular Carcinoma. This distinction depends entirely on identifying **capsular or vascular invasion**, which can only be visualized on a formal histopathological examination (HPE) of the entire specimen. Therefore, an excision biopsy (often via diagnostic lobectomy) remains the "gold standard" to definitively differentiate benign from malignant lesions. 2. **Why Other Options are Incorrect:** * **FNAC:** While it is the **initial investigation of choice** and the best screening tool for thyroid nodules, it provides cytological details only. It cannot evaluate tissue architecture, making it unreliable for follicular malignancies. * **CT Scan & MRI:** These are imaging modalities used primarily for staging, assessing retrosternal extension, or evaluating local invasion into the trachea/esophagus. They cannot provide a microscopic diagnosis of malignancy. **High-Yield Clinical Pearls for NEET-PG:** * **Best Initial Test:** FNAC. * **Most Accurate/Definitive Test:** Excision Biopsy (HPE). * **FNAC Limitation:** It cannot diagnose Follicular Carcinoma or Hurthle cell carcinoma. * **Bethesda System:** Used to report thyroid cytology; Category IV (Follicular Neoplasm) usually warrants surgical excision for a definitive diagnosis. * **Papillary Carcinoma:** Can often be diagnosed on FNAC due to characteristic nuclear features (Orphan Annie eye nuclei, Psammoma bodies).

Question 166: A 29-year-old woman underwent a thyroidectomy. Postoperatively, the patient presented with hoarseness. Which of the following nerves was most likely injured during the operation?

A. Internal laryngeal
B. External laryngeal
C. Recurrent laryngeal (Correct Answer)
D. Superior laryngeal

Explanation: **Explanation:** The patient’s presentation of **hoarseness** following thyroidectomy is a classic sign of **Recurrent Laryngeal Nerve (RLN)** injury. **1. Why Recurrent Laryngeal Nerve is Correct:** The RLN provides motor supply to all intrinsic muscles of the larynx except the cricothyroid. It also provides sensory innervation to the larynx below the vocal cords. * **Unilateral injury:** Results in the vocal cord assuming a paramedian position, leading to **hoarseness** and a weak, breathy voice. * **Bilateral injury:** Can lead to airway obstruction and stridor, often requiring an emergency tracheostomy. The RLN is most vulnerable during the ligation of the **inferior thyroid artery**, as it closely approximates the artery near the lower pole of the thyroid. **2. Analysis of Incorrect Options:** * **External Laryngeal Nerve (ELN):** This nerve supplies the **cricothyroid muscle**. Injury (usually during ligation of the superior thyroid artery) leads to an inability to tense the vocal cords, resulting in a **loss of high-pitched tones** and easy vocal fatigue, but not frank hoarseness. * **Internal Laryngeal Nerve:** This is a purely **sensory** nerve supplying the larynx above the vocal cords. Injury results in a loss of the cough reflex, increasing the risk of aspiration, but does not affect voice quality. * **Superior Laryngeal Nerve (SLN):** This nerve divides into the internal and external branches. While "SLN injury" is a broad term, the specific motor deficit causing voice changes is attributed to its external branch. **3. NEET-PG High-Yield Pearls:** * **Most common nerve injured** in thyroidectomy: Recurrent Laryngeal Nerve. * **Nerve at risk during Superior Thyroid Artery ligation:** External Laryngeal Nerve. * **Nerve at risk during Inferior Thyroid Artery ligation:** Recurrent Laryngeal Nerve. * **Standard of Care:** Intraoperative nerve monitoring is increasingly used to identify and preserve these nerves.

Question 167: What is the commonest thyroid tumor in MEN (Multiple Endocrine Neoplasia)?

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

Explanation: **Explanation:** The correct answer is **Medullary Thyroid Carcinoma (MTC)**. **Why it is correct:** Medullary thyroid carcinoma originates from the **parafollicular C-cells**, which are derived from the neural crest. This tumor is a defining component of **Multiple Endocrine Neoplasia (MEN) type 2A and 2B**. In these syndromes, MTC occurs due to a germline mutation in the **RET proto-oncogene**. It is often the first clinical manifestation of the syndrome, is typically multifocal, and occurs at a much younger age compared to sporadic cases. **Why the other options are incorrect:** * **A. Follicular Carcinoma:** This is a differentiated thyroid cancer derived from follicular cells. It is associated with iodine deficiency and RAS mutations but has no association with MEN syndromes. * **B. Papillary Carcinoma:** While it is the most common thyroid cancer overall in the general population, it is not linked to MEN. It is associated with radiation exposure and BRAF mutations. * **C. Anaplastic Carcinoma:** This is a highly aggressive, undifferentiated tumor seen in elderly patients. It is not a feature of the MEN spectrum. **High-Yield Clinical Pearls for NEET-PG:** * **MEN 2A (Sipple Syndrome):** MTC + Pheochromocytoma + Parathyroid Hyperplasia. * **MEN 2B (Wermer-like):** MTC + Pheochromocytoma + Mucosal Neuromas/Marfanoid habitus. * **Tumor Marker:** Calcitonin is the specific marker used for diagnosis and monitoring recurrence. * **Prophylactic Surgery:** In children with known RET mutations, a prophylactic total thyroidectomy is recommended (age depends on the specific codon mutation). * **Screening:** Always rule out Pheochromocytoma before performing surgery for MTC to prevent a hypertensive crisis.

Question 168: Which of the following is FALSE regarding follicular thyroid cancer?

A. It is more common in endemic areas and is more malignant in females.
B. Fine needle aspiration cytology (FNAC) cannot reliably differentiate follicular adenoma from follicular carcinoma.
C. It is not encapsulated. (Correct Answer)
D. It is common at 50 years of age.

Explanation: **Explanation** Follicular Thyroid Carcinoma (FTC) is the second most common thyroid malignancy. Understanding its pathological and clinical behavior is crucial for NEET-PG. **Why Option C is the Correct (False) Statement:** Unlike Papillary Thyroid Carcinoma (PTC), which is often unencapsulated, **Follicular Thyroid Carcinoma is typically encapsulated.** The diagnosis of malignancy depends entirely on demonstrating **capsular invasion** or **vascular invasion** on histopathology. If the tumor is confined within the capsule without invasion, it is classified as a Follicular Adenoma. **Analysis of Other Options:** * **Option A:** FTC is indeed more prevalent in iodine-deficient (endemic) areas. While thyroid cancers are more common in females, the prognosis is often more aggressive (more malignant) in females and older age groups. * **Option B:** This is a classic high-yield fact. **FNAC cannot differentiate between follicular adenoma and carcinoma** because it only evaluates cellular morphology, not the architectural integrity of the capsule or blood vessels. * **Option D:** FTC typically presents in an older age group compared to PTC, with a peak incidence around the 5th decade (50 years). **Clinical Pearls for NEET-PG:** * **Spread:** FTC spreads primarily via the **hematogenous route** (blood), most commonly to the lungs and bones (osteolytic lesions). PTC spreads via lymphatics. * **Hürthle Cell Carcinoma:** A variant of FTC characterized by oxyphilic cells; it is more likely to spread to lymph nodes than typical FTC. * **Treatment:** Total thyroidectomy followed by Radioactive Iodine (RAI) ablation is the standard for tumors >1 cm. * **Marker:** Serum **Thyroglobulin** is used as a tumor marker for post-operative surveillance.

Question 169: Which of the following is a key step in the surgical management of a thyroglossal cyst?

A. Excision of the central portion of the hyoid bone (Correct Answer)
B. Dissection of the sternothyroid muscle
C. Isthmusectomy with subtotal thyroidectomy
D. Dissection of the strap muscles of the neck

Explanation: The surgical management of a thyroglossal cyst is defined by the **Sistrunk Procedure**. This procedure is based on the embryological development of the thyroid gland, which descends from the foramen caecum at the base of the tongue to its final position in the neck. ### Why Option A is Correct The thyroglossal duct has an intimate relationship with the **hyoid bone**, often passing anterior, posterior, or even through it. To ensure complete removal and prevent recurrence, the **central portion of the hyoid bone** must be excised along with the cyst and the entire ductal tract up to the foramen caecum. Failure to remove the hyoid bone is the most common cause of recurrence. ### Why Other Options are Incorrect * **Option B & D:** While strap muscles (including the sternothyroid) are retracted or divided to gain access to the cyst, their dissection is a surgical approach step, not the "key" curative step of the procedure. * **Option C:** Isthmusectomy and subtotal thyroidectomy are used for thyroid pathologies (like multinodular goiter or certain malignancies). They are not indicated for a thyroglossal cyst unless there is a rare associated thyroid malignancy. ### High-Yield Clinical Pearls for NEET-PG * **Most common location:** Subhyoid (65%). * **Clinical Sign:** The cyst moves upward on **protrusion of the tongue** (due to its attachment to the foramen caecum) and on deglutition. * **Diagnosis:** Ultrasound is the initial investigation to confirm the cyst and ensure a normal thyroid gland is present elsewhere. * **Recurrence Rate:** Reduced from ~50% to <5% by performing the Sistrunk Procedure. * **Malignancy:** Most common cancer in a thyroglossal cyst is **Papillary Carcinoma of the Thyroid**.

Question 170: What is the investigation of choice for a discrete thyroid swelling?

A. Isotope scans
B. Ultrasonography
C. Autoantibody titers
D. FNAC (Correct Answer)

Explanation: **Explanation:** The primary goal in evaluating a discrete thyroid swelling (thyroid nodule) is to differentiate between benign and malignant lesions. **Why FNAC is the Correct Answer:** **Fine Needle Aspiration Cytology (FNAC)** is the **investigation of choice** and the gold standard for the initial evaluation of a thyroid nodule. It is highly cost-effective, easy to perform, and has high sensitivity and specificity (approx. 95%) for detecting malignancy. Results are typically categorized using the **Bethesda System**, which guides further surgical or medical management. **Analysis of Incorrect Options:** * **A. Isotope Scans:** Formerly popular, they are now reserved for patients with low TSH levels to identify "hot" (functioning) nodules. Most thyroid cancers are "cold," but since most cold nodules are also benign, the scan lacks the specificity to diagnose malignancy. * **B. Ultrasonography:** While USG is the **first-line imaging** modality to confirm the presence of a nodule and assess suspicious features (e.g., microcalcifications, irregular margins), it cannot provide a definitive pathological diagnosis like FNAC. * **C. Autoantibody Titers:** These are useful for diagnosing autoimmune conditions like Hashimoto’s thyroiditis or Graves' disease but do not help in the diagnostic workup of a discrete mass to rule out cancer. **High-Yield Clinical Pearls for NEET-PG:** * **Best Initial Test:** TSH levels. * **Best Imaging:** Ultrasound (USG). * **Investigation of Choice (IOC):** FNAC. * **Limitation of FNAC:** It cannot distinguish between **Follicular Adenoma and Follicular Carcinoma** because it cannot assess capsular or vascular invasion. Histopathology (post-thyroidectomy) is required. * **Most common indication for surgery** in a thyroid nodule is a "Malignant" or "Suspicious" FNAC report.

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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