Endocrine Surgery — MCQs

Q: Where is a bruit typically heard in the thyroid gland?

Upper pole. **Explanation:** The presence of a thyroid bruit is a classic clinical sign of **Graves' disease** (toxic diffuse goiter). It occurs due to the hyperdynamic circulation and significantly increased vascularity of the gland. **Why the Upper Pole is Correct:** The bruit is most commonly heard over the **upper pole** of the thyroid gland. This is because the **superior thyroid artery**, a direct branch of the external carotid artery, enters the gland at the upper pole. Due to its proximity to a major high-pressure arterial trunk and its relatively superficial location, the turbulent blood flow (hypervascularity) is most audible at this site. **Analysis of Incorrect Options:** * **Lower Pole:** While the inferior thyroid artery (from the thyrocervical trunk) supplies the lower pole, it is situated deeper and has a more tortuous course, making a bruit less likely to be localized here compared to the superior pole. * **Middle Part & Lateral Aspect:** These areas represent the body of the lobes. While vascularity is increased throughout in Graves' disease, the primary inflow points (the poles) are the high-yield areas for auscultation. **High-Yield Clinical Pearls for NEET-PG:** 1. **Bruit vs. Thrill:** A bruit is an auditory sign (auscultation), whereas a **thrill** is its tactile equivalent (palpation). Both indicate Graves' disease. 2. **Differential Diagnosis:** A thyroid bruit must be distinguished from a **venous hum** (disappears with pressure over the internal jugular vein) and a **carotid bruit** (heard lateral to the gland). 3. **Significance:** The presence of a bruit is highly specific for Graves' disease and helps differentiate it from other causes of thyrotoxicosis, such as toxic multinodular goiter or thyroiditis.

Q: Which of the following statements is FALSE regarding medullary cancer of the thyroid?

These cancers take up Radioactive Iodine. ### Explanation **Medullary Thyroid Carcinoma (MTC)** arises from the **parafollicular C-cells**, which are neuroendocrine cells derived from the neural crest. This fundamental embryological origin is the key to understanding its clinical behavior and management. **Why Option D is the Correct (False) Statement:** Radioactive Iodine (RAI) uptake depends on the expression of the Sodium-Iodide Symporter (NIS), which is exclusive to follicular epithelial cells. Since MTC originates from C-cells (not follicular cells), these tumors **do not take up radioactive iodine**. Consequently, RAI ablation is not a therapeutic option for MTC, unlike papillary or follicular thyroid cancers. **Analysis of Other Options:** * **Option A (True):** C-cells naturally produce **Calcitonin**. Elevated serum calcitonin is a highly sensitive and specific tumor marker for MTC, used for both diagnosis and monitoring recurrence. * **Option B (True):** Approximately **20–25%** of MTC cases are familial, occurring as part of **MEN 2A, MEN 2B**, or Familial MTC (FMTC) syndromes, usually due to germline **RET proto-oncogene** mutations. The remaining 75–80% are sporadic. * **Option C (True):** Diarrhea occurs in about **30%** of patients, particularly in advanced or metastatic disease. It is caused by the hypersecretion of calcitonin, prostaglandins, or serotonin, which increases intestinal motility. **High-Yield Clinical Pearls for NEET-PG:** * **Amyloid Stroma:** Histologically, MTC is characterized by nests of cells separated by amyloid deposits (stained by Congo Red). * **CEA:** Carcinoembryonic Antigen is another important tumor marker for MTC. * **Screening:** All patients diagnosed with MTC must be screened for **RET mutations** and **Pheochromocytoma** (before surgery) to rule out MEN 2. * **Treatment:** The primary treatment is Total Thyroidectomy with central compartment neck dissection.

Q: Which type of thyroid carcinoma is associated with hypocalcemia?

Medullary carcinoma. **Explanation:** **Medullary Thyroid Carcinoma (MTC)** is the correct answer because of its unique cellular origin. Unlike other thyroid cancers that arise from follicular cells, MTC originates from the **Parafollicular C-cells** of the thyroid gland. These cells are responsible for the secretion of **Calcitonin**. In MTC, there is a pathological hypersecretion of Calcitonin. Calcitonin acts as a physiological antagonist to Parathyroid Hormone (PTH); it lowers serum calcium levels by inhibiting bone resorption (osteoclast activity) and increasing renal calcium excretion. While clinical hypocalcemia is rare in MTC patients due to compensatory mechanisms, the biochemical association with calcium-lowering hormones makes it the characteristic answer for this question. **Why other options are incorrect:** * **Papillary and Follicular Carcinoma:** These are "Differentiated Thyroid Cancers" (DTC) arising from follicular cells. They secrete Thyroglobulin, not Calcitonin, and have no direct effect on calcium metabolism. * **Anaplastic Carcinoma:** This is an undifferentiated, highly aggressive tumor. While it can cause local invasion (leading to hoarseness or dysphagia), it does not produce hormones that regulate calcium. **High-Yield Clinical Pearls for NEET-PG:** * **Tumor Marker:** Calcitonin is used for both diagnosis and monitoring recurrence in MTC. Carcinoembryonic Antigen (CEA) is also often elevated. * **Genetics:** Approximately 25% of MTC cases are familial, associated with **MEN 2A and 2B** syndromes (RET proto-oncogene mutation). * **Amyloid Stroma:** Histologically, MTC is characterized by polygonal cells with **amyloid deposits** (derived from pro-calcitonin) that stain with Congo Red. * **Spread:** MTC spreads via both lymphatic and hematogenous routes.

Q: A patient presents with secondary adrenal masses. What is the most common primary site for such metastases?

Lung. **Explanation:** The adrenal glands are a highly vascularized site, making them the fourth most common site for hematogenous metastasis in the body (after the liver, lungs, and bones). **1. Why Lung is Correct:** **Lung cancer** is the most common primary malignancy to metastasize to the adrenal glands. Approximately 30-40% of patients with lung cancer will have adrenal involvement at the time of autopsy. Both Small Cell Lung Cancer (SCLC) and Non-Small Cell Lung Cancer (NSCLC), particularly **adenocarcinoma**, frequently spread to the adrenals. In clinical practice, when a unilateral or bilateral adrenal mass is found in a patient with a history of smoking or respiratory symptoms, lung cancer is the primary suspect. **2. Analysis of Incorrect Options:** * **Kidney (Renal Cell Carcinoma):** While RCC can spread to the adrenal gland (often via direct extension or venous routes), it is less common than lung-derived metastases. * **Breast:** Breast cancer is the second most common primary site for adrenal metastasis. While frequent, it statistically trails behind lung cancer. * **Stomach:** Gastrointestinal malignancies (Stomach, Colon) can metastasize to the adrenals, but they are significantly less common than thoracic or breast primaries. **3. Clinical Pearls for NEET-PG:** * **Bilateral Involvement:** Metastatic disease is the most common cause of bilateral adrenal masses. * **Imaging:** On CT, metastases typically show high unenhanced attenuation (>10 HU) and slow washout of contrast, unlike benign adenomas. * **Biopsy Rule:** Never perform a Fine Needle Aspiration (FNA) of an adrenal mass until **Pheochromocytoma** has been ruled out (via plasma/urine metanephrines) to avoid a life-threatening hypertensive crisis. * **Adrenal Insufficiency:** Clinical Addison’s disease is rare in metastasis unless >90% of both glands are destroyed.

Q: What is the best treatment for cervical lymph node involvement in papillary carcinoma of the thyroid?

Radical neck dissection. **Explanation:** Papillary Thyroid Carcinoma (PTC) is the most common thyroid malignancy and is characterized by its tendency for **lymphatic spread** to the cervical lymph nodes. **Why Radical Neck Dissection is Correct:** The primary management for PTC with clinically or radiologically evident cervical lymphadenopathy is surgical clearance. While "Modified Radical Neck Dissection" (MRND) is the preferred modern standard to preserve the spinal accessory nerve, internal jugular vein, and sternocleidomastoid muscle, the term **Radical Neck Dissection** (in the context of this MCQ) represents the surgical removal of the involved nodal compartments. PTC is relatively resistant to non-surgical modalities; therefore, therapeutic neck dissection is essential to reduce local recurrence and improve survival. **Why Other Options are Incorrect:** * **A. Radioactive Iodine (RAI):** RAI is used as adjuvant therapy *after* surgery to ablate remnant thyroid tissue or treat micrometastases. It is not a substitute for surgical excision of gross nodal disease. * **B. Chemotherapy:** PTC is generally chemo-resistant. Chemotherapy is reserved only for palliative care in advanced, refractory cases. * **D. Steroids:** These have no role in the definitive treatment of thyroid malignancies. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site of metastasis:** Level VI (Central compartment) nodes. * **Prognosis:** PTC has an excellent 10-year survival rate (>90%), even with nodal involvement. * **Psammoma bodies:** A classic histological finding in PTC (calcified laminated structures). * **Orphan Annie Eye nuclei:** Characteristic nuclear clearing seen on histopathology. * **Prophylactic Neck Dissection:** Not routinely recommended for PTC unless nodes are clinically palpable or detected on ultrasound (therapeutic dissection).

Q: A patient presents with a 2 cm midline neck swelling. HPE reveals orphan annie eye nuclei. What is the most likely diagnosis?

Papillary thyroid carcinoma. ### Explanation The correct answer is **Papillary Thyroid Carcinoma (PTC)**. **1. Why Papillary Thyroid Carcinoma is Correct:** The presence of **"Orphan Annie eye nuclei"** is the pathognomonic histological hallmark of Papillary Thyroid Carcinoma. These are large, overlapping nuclei with a clear or ground-glass appearance due to finely dispersed chromatin. PTC is the most common type of thyroid malignancy (80–85%) and typically presents as a painless, slow-growing midline neck swelling (thyroid nodule). Other characteristic histological features include **Psammoma bodies** (laminated calcifications) and nuclear grooves. **2. Why the Other Options are Incorrect:** * **Medullary Thyroid Carcinoma (MTC):** Arises from parafollicular C-cells. Histology shows nests of cells in an **amyloid stroma** (stains with Congo Red). It is associated with MEN 2A and 2B syndromes. * **Toxic Nodular Goiter:** This is a functional (hyperthyroid) state characterized by follicular hyperplasia without malignant nuclear features. It presents with symptoms of thyrotoxicosis (tachycardia, tremors). * **Follicular Thyroid Carcinoma (FTC):** Diagnosis depends on demonstrating **capsular or vascular invasion**, which cannot be determined by FNA alone. It does not exhibit Orphan Annie eye nuclei. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common thyroid cancer:** Papillary Thyroid Carcinoma. * **Best Prognosis:** Papillary Thyroid Carcinoma. * **Route of Spread:** PTC spreads primarily via **lymphatics** (level VI nodes), whereas FTC spreads **hematogenously** (to bone/lungs). * **Risk Factor:** Prior exposure to ionizing radiation is strongly linked to PTC. * **Genetic Mutation:** Most commonly associated with **BRAF mutations** (specifically V600E) and RET/PTC rearrangements.

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

Papillary carcinoma. **Explanation:** **Papillary Thyroid Carcinoma (PTC)** is the most common type of thyroid malignancy, accounting for approximately **80–85%** of all thyroid cancers. It is typically associated with radiation exposure and has an excellent prognosis. The diagnosis is characterized by distinct nuclear features such as **Orphan Annie eye nuclei** (clear nuclei), **Psammoma bodies** (laminated calcifications), and nuclear grooves. **Analysis of Options:** * **Follicular Carcinoma (Option B):** The second most common type (approx. 10–15%). It is more prevalent in iodine-deficient areas and spreads primarily via the **hematogenous route** (to bone and lungs), unlike PTC which spreads via lymphatics. * **Medullary Carcinoma (Option C):** Accounts for about 5% of cases. It arises from the **parafollicular C-cells** and secretes **Calcitonin**. It can be sporadic or associated with MEN 2A/2B syndromes (RET proto-oncogene mutation). * **Anaplastic Carcinoma (Option D):** The rarest (<2%) but most aggressive form. It typically presents in elderly patients as a rapidly enlarging neck mass with a very poor prognosis. **High-Yield Clinical Pearls for NEET-PG:** * **Route of Spread:** Papillary = Lymphatic (most common site: Level VI nodes); Follicular = Hematogenous. * **Investigation of Choice:** FNAC is the gold standard for thyroid nodules, but it **cannot** distinguish between follicular adenoma and follicular carcinoma (requires histopathology to see capsular/vascular invasion). * **Psammoma Bodies:** Most commonly seen in Papillary CA, Meningioma, and Serous Cystadenocarcinoma of the ovary. * **Treatment:** Total thyroidectomy is the mainstay for most cases >1cm, often followed by Radioiodine (I-131) ablation.

Q: Swelling of the thyroid gland that does not move with deglutition is/are:

All of the above. **Explanation:** The hallmark clinical sign of a thyroid swelling is that it **moves with deglutition** (swallowing). This occurs because the thyroid gland is enclosed by the **pretracheal fascia**, which attaches the gland to the laryngeal cartilages and the hyoid bone. When these structures move upward during swallowing, the thyroid moves with them. However, certain conditions can prevent this movement: 1. **Retrosternal Goiter (Option A):** When a goiter extends significantly into the mediastinum (thoracic inlet), it can become "wedged" or "impacted" behind the sternum. The bony cage of the thoracic inlet restricts the upward excursion of the mass during swallowing. 2. **Riedel’s Thyroiditis/Goiter (Option B):** This is a rare chronic inflammatory condition characterized by dense, "woody" fibrosis. The fibrosis extends beyond the thyroid capsule to involve adjacent structures like the strap muscles, trachea, and carotid sheath, effectively "tethering" the gland and preventing movement. 3. **Anaplastic Carcinoma (Option C):** This is a highly aggressive malignancy. It frequently exhibits extrathyroidal extension, infiltrating surrounding muscles, nerves, and fascia. This local invasion causes the gland to become fixed to the neck structures. **Clinical Pearls for NEET-PG:** * **Thyroglossal Cyst:** Moves with deglutition AND **protrusion of the tongue** (due to its attachment to the hyoid bone via the tract). * **Pemberton’s Sign:** Seen in retrosternal goiters; raising the arms above the head causes facial congestion and respiratory distress due to thoracic inlet obstruction. * **Hard/Woody Thyroid:** Differential includes Riedel’s Thyroiditis and Anaplastic Carcinoma. Riedel’s is typically seen in younger patients, while Anaplastic is seen in the elderly.

Q: What is the most common subtype of thyroid cancer?

Papillary carcinoma. **Explanation:** **Papillary Thyroid Carcinoma (PTC)** is the most common subtype of thyroid cancer, accounting for approximately **80–85%** of all thyroid malignancies. It is associated with exposure to ionizing radiation and generally carries an excellent prognosis. The diagnosis is characteristically made via Fine Needle Aspiration Cytology (FNAC), showing pathognomonic nuclear features such as **Orphan Annie eye nuclei** (clear nuclei), **Psammoma bodies** (laminated calcifications), and nuclear grooves. **Analysis of Incorrect Options:** * **Follicular Carcinoma (Option C):** The second most common subtype (approx. 10%). Unlike PTC, it spreads hematogenously (to bone and lungs) and cannot be diagnosed by FNAC alone, as it requires histological evidence of capsular or vascular invasion. * **Medullary Carcinoma (Option A):** Accounts for about 5% of cases. It arises from **Parafollicular C-cells** and secretes Calcitonin. It is associated with MEN 2A and 2B syndromes. * **Anaplastic Carcinoma (Option D):** The rarest (<2%) but most aggressive form. It typically presents in elderly patients as a rapidly enlarging neck mass with a very poor prognosis. **High-Yield Clinical Pearls for NEET-PG:** * **Route of Spread:** Papillary spreads via **lymphatics** (Level VI nodes first); Follicular spreads via **blood**. * **Investigation of Choice:** FNAC is the gold standard for thyroid nodules (except for Follicular CA). * **Prognostic Scoring:** AMES and MACIS scores are used specifically for Papillary carcinoma. * **Treatment:** Total thyroidectomy followed by Radioiodine (I-131) ablation is the standard for most cases >1cm.

Endocrine Surgery Indian Medical PG Practice Questions and MCQs

Question 1: Where is a bruit typically heard in the thyroid gland?

A. Upper pole (Correct Answer)
B. Lower pole
C. Middle part
D. Lateral aspect

Explanation: **Explanation:** The presence of a thyroid bruit is a classic clinical sign of **Graves' disease** (toxic diffuse goiter). It occurs due to the hyperdynamic circulation and significantly increased vascularity of the gland. **Why the Upper Pole is Correct:** The bruit is most commonly heard over the **upper pole** of the thyroid gland. This is because the **superior thyroid artery**, a direct branch of the external carotid artery, enters the gland at the upper pole. Due to its proximity to a major high-pressure arterial trunk and its relatively superficial location, the turbulent blood flow (hypervascularity) is most audible at this site. **Analysis of Incorrect Options:** * **Lower Pole:** While the inferior thyroid artery (from the thyrocervical trunk) supplies the lower pole, it is situated deeper and has a more tortuous course, making a bruit less likely to be localized here compared to the superior pole. * **Middle Part & Lateral Aspect:** These areas represent the body of the lobes. While vascularity is increased throughout in Graves' disease, the primary inflow points (the poles) are the high-yield areas for auscultation. **High-Yield Clinical Pearls for NEET-PG:** 1. **Bruit vs. Thrill:** A bruit is an auditory sign (auscultation), whereas a **thrill** is its tactile equivalent (palpation). Both indicate Graves' disease. 2. **Differential Diagnosis:** A thyroid bruit must be distinguished from a **venous hum** (disappears with pressure over the internal jugular vein) and a **carotid bruit** (heard lateral to the gland). 3. **Significance:** The presence of a bruit is highly specific for Graves' disease and helps differentiate it from other causes of thyrotoxicosis, such as toxic multinodular goiter or thyroiditis.

Question 2: Which of the following statements is FALSE regarding medullary cancer of the thyroid?

A. Secrete Calcitonin
B. 20-25% are familial
C. Diarrhea is seen in 30%
D. These cancers take up Radioactive Iodine (Correct Answer)

Explanation: ### Explanation **Medullary Thyroid Carcinoma (MTC)** arises from the **parafollicular C-cells**, which are neuroendocrine cells derived from the neural crest. This fundamental embryological origin is the key to understanding its clinical behavior and management. **Why Option D is the Correct (False) Statement:** Radioactive Iodine (RAI) uptake depends on the expression of the Sodium-Iodide Symporter (NIS), which is exclusive to follicular epithelial cells. Since MTC originates from C-cells (not follicular cells), these tumors **do not take up radioactive iodine**. Consequently, RAI ablation is not a therapeutic option for MTC, unlike papillary or follicular thyroid cancers. **Analysis of Other Options:** * **Option A (True):** C-cells naturally produce **Calcitonin**. Elevated serum calcitonin is a highly sensitive and specific tumor marker for MTC, used for both diagnosis and monitoring recurrence. * **Option B (True):** Approximately **20–25%** of MTC cases are familial, occurring as part of **MEN 2A, MEN 2B**, or Familial MTC (FMTC) syndromes, usually due to germline **RET proto-oncogene** mutations. The remaining 75–80% are sporadic. * **Option C (True):** Diarrhea occurs in about **30%** of patients, particularly in advanced or metastatic disease. It is caused by the hypersecretion of calcitonin, prostaglandins, or serotonin, which increases intestinal motility. **High-Yield Clinical Pearls for NEET-PG:** * **Amyloid Stroma:** Histologically, MTC is characterized by nests of cells separated by amyloid deposits (stained by Congo Red). * **CEA:** Carcinoembryonic Antigen is another important tumor marker for MTC. * **Screening:** All patients diagnosed with MTC must be screened for **RET mutations** and **Pheochromocytoma** (before surgery) to rule out MEN 2. * **Treatment:** The primary treatment is Total Thyroidectomy with central compartment neck dissection.

Question 3: Which type of thyroid carcinoma is associated with hypocalcemia?

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

Explanation: **Explanation:** **Medullary Thyroid Carcinoma (MTC)** is the correct answer because of its unique cellular origin. Unlike other thyroid cancers that arise from follicular cells, MTC originates from the **Parafollicular C-cells** of the thyroid gland. These cells are responsible for the secretion of **Calcitonin**. In MTC, there is a pathological hypersecretion of Calcitonin. Calcitonin acts as a physiological antagonist to Parathyroid Hormone (PTH); it lowers serum calcium levels by inhibiting bone resorption (osteoclast activity) and increasing renal calcium excretion. While clinical hypocalcemia is rare in MTC patients due to compensatory mechanisms, the biochemical association with calcium-lowering hormones makes it the characteristic answer for this question. **Why other options are incorrect:** * **Papillary and Follicular Carcinoma:** These are "Differentiated Thyroid Cancers" (DTC) arising from follicular cells. They secrete Thyroglobulin, not Calcitonin, and have no direct effect on calcium metabolism. * **Anaplastic Carcinoma:** This is an undifferentiated, highly aggressive tumor. While it can cause local invasion (leading to hoarseness or dysphagia), it does not produce hormones that regulate calcium. **High-Yield Clinical Pearls for NEET-PG:** * **Tumor Marker:** Calcitonin is used for both diagnosis and monitoring recurrence in MTC. Carcinoembryonic Antigen (CEA) is also often elevated. * **Genetics:** Approximately 25% of MTC cases are familial, associated with **MEN 2A and 2B** syndromes (RET proto-oncogene mutation). * **Amyloid Stroma:** Histologically, MTC is characterized by polygonal cells with **amyloid deposits** (derived from pro-calcitonin) that stain with Congo Red. * **Spread:** MTC spreads via both lymphatic and hematogenous routes.

Question 4: A patient presents with secondary adrenal masses. What is the most common primary site for such metastases?

A. Lung (Correct Answer)
B. Kidney
C. Breast
D. Stomach

Explanation: **Explanation:** The adrenal glands are a highly vascularized site, making them the fourth most common site for hematogenous metastasis in the body (after the liver, lungs, and bones). **1. Why Lung is Correct:** **Lung cancer** is the most common primary malignancy to metastasize to the adrenal glands. Approximately 30-40% of patients with lung cancer will have adrenal involvement at the time of autopsy. Both Small Cell Lung Cancer (SCLC) and Non-Small Cell Lung Cancer (NSCLC), particularly **adenocarcinoma**, frequently spread to the adrenals. In clinical practice, when a unilateral or bilateral adrenal mass is found in a patient with a history of smoking or respiratory symptoms, lung cancer is the primary suspect. **2. Analysis of Incorrect Options:** * **Kidney (Renal Cell Carcinoma):** While RCC can spread to the adrenal gland (often via direct extension or venous routes), it is less common than lung-derived metastases. * **Breast:** Breast cancer is the second most common primary site for adrenal metastasis. While frequent, it statistically trails behind lung cancer. * **Stomach:** Gastrointestinal malignancies (Stomach, Colon) can metastasize to the adrenals, but they are significantly less common than thoracic or breast primaries. **3. Clinical Pearls for NEET-PG:** * **Bilateral Involvement:** Metastatic disease is the most common cause of bilateral adrenal masses. * **Imaging:** On CT, metastases typically show high unenhanced attenuation (>10 HU) and slow washout of contrast, unlike benign adenomas. * **Biopsy Rule:** Never perform a Fine Needle Aspiration (FNA) of an adrenal mass until **Pheochromocytoma** has been ruled out (via plasma/urine metanephrines) to avoid a life-threatening hypertensive crisis. * **Adrenal Insufficiency:** Clinical Addison’s disease is rare in metastasis unless >90% of both glands are destroyed.

Question 5: Which of the following statements is not true regarding medullary thyroid carcinoma?

A. They are a type of neuroendocrine tumor.
B. They are associated with MEN 2A and 2B syndromes.
C. They comprise approximately 25% of all thyroid malignancies. (Correct Answer)
D. Tumor cells may secrete serotonin, ACTH, and VIP.

Explanation: **Explanation** Medullary Thyroid Carcinoma (MTC) is a unique thyroid malignancy arising from the **parafollicular C-cells**, which are derived from the **neural crest**. **1. Why Option C is the correct answer (The False Statement):** MTC is relatively rare, accounting for only **5% to 8%** of all thyroid malignancies. The most common thyroid cancer is Papillary Thyroid Carcinoma (PTC), which comprises about 80–85%. Stating that MTC represents 25% is a significant overestimation. **2. Analysis of other options:** * **Option A (True):** Because they originate from neural crest cells and secrete hormones, they are classified as **neuroendocrine tumors**. * **Option B (True):** Approximately 25% of MTC cases are hereditary. It is a key component of **MEN 2A** (MTC, Pheochromocytoma, Hyperparathyroidism) and **MEN 2B** (MTC, Pheochromocytoma, Mucosal neuromas, Marfanoid habitus). * **Option D (True):** While Calcitonin is the primary marker, MTC cells are pluripotential and can secrete ectopic hormones like **Serotonin** (causing flushing/diarrhea), **ACTH** (causing Cushing’s syndrome), and **VIP**. **High-Yield Clinical Pearls for NEET-PG:** * **Biomarkers:** **Calcitonin** (used for diagnosis and monitoring recurrence) and **CEA**. * **Histology:** Characterized by **Amyloid stroma** (stained by Congo Red showing apple-green birefringence). * **Genetics:** Strongly associated with **RET proto-oncogene** mutations. Prophylactic thyroidectomy is indicated in carriers. * **Spread:** Unlike papillary CA (lymphatic) or follicular CA (hematogenous), MTC spreads via **both** lymphatic and hematogenous routes early. * **Management:** Total thyroidectomy with central compartment neck dissection is the treatment of choice; MTC does **not** respond to Radioiodine (I-131) therapy.

Question 6: What is the best treatment for cervical lymph node involvement in papillary carcinoma of the thyroid?

A. Radioactive iodine
B. Chemotherapy
C. Radical neck dissection (Correct Answer)
D. Steroid

Explanation: **Explanation:** Papillary Thyroid Carcinoma (PTC) is the most common thyroid malignancy and is characterized by its tendency for **lymphatic spread** to the cervical lymph nodes. **Why Radical Neck Dissection is Correct:** The primary management for PTC with clinically or radiologically evident cervical lymphadenopathy is surgical clearance. While "Modified Radical Neck Dissection" (MRND) is the preferred modern standard to preserve the spinal accessory nerve, internal jugular vein, and sternocleidomastoid muscle, the term **Radical Neck Dissection** (in the context of this MCQ) represents the surgical removal of the involved nodal compartments. PTC is relatively resistant to non-surgical modalities; therefore, therapeutic neck dissection is essential to reduce local recurrence and improve survival. **Why Other Options are Incorrect:** * **A. Radioactive Iodine (RAI):** RAI is used as adjuvant therapy *after* surgery to ablate remnant thyroid tissue or treat micrometastases. It is not a substitute for surgical excision of gross nodal disease. * **B. Chemotherapy:** PTC is generally chemo-resistant. Chemotherapy is reserved only for palliative care in advanced, refractory cases. * **D. Steroids:** These have no role in the definitive treatment of thyroid malignancies. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site of metastasis:** Level VI (Central compartment) nodes. * **Prognosis:** PTC has an excellent 10-year survival rate (>90%), even with nodal involvement. * **Psammoma bodies:** A classic histological finding in PTC (calcified laminated structures). * **Orphan Annie Eye nuclei:** Characteristic nuclear clearing seen on histopathology. * **Prophylactic Neck Dissection:** Not routinely recommended for PTC unless nodes are clinically palpable or detected on ultrasound (therapeutic dissection).

Question 7: A patient presents with a 2 cm midline neck swelling. HPE reveals orphan annie eye nuclei. What is the most likely diagnosis?

A. Papillary thyroid carcinoma (Correct Answer)
B. Medullary thyroid carcinoma
C. Toxic nodular goiter
D. Follicular thyroid carcinoma

Explanation: ### Explanation The correct answer is **Papillary Thyroid Carcinoma (PTC)**. **1. Why Papillary Thyroid Carcinoma is Correct:** The presence of **"Orphan Annie eye nuclei"** is the pathognomonic histological hallmark of Papillary Thyroid Carcinoma. These are large, overlapping nuclei with a clear or ground-glass appearance due to finely dispersed chromatin. PTC is the most common type of thyroid malignancy (80–85%) and typically presents as a painless, slow-growing midline neck swelling (thyroid nodule). Other characteristic histological features include **Psammoma bodies** (laminated calcifications) and nuclear grooves. **2. Why the Other Options are Incorrect:** * **Medullary Thyroid Carcinoma (MTC):** Arises from parafollicular C-cells. Histology shows nests of cells in an **amyloid stroma** (stains with Congo Red). It is associated with MEN 2A and 2B syndromes. * **Toxic Nodular Goiter:** This is a functional (hyperthyroid) state characterized by follicular hyperplasia without malignant nuclear features. It presents with symptoms of thyrotoxicosis (tachycardia, tremors). * **Follicular Thyroid Carcinoma (FTC):** Diagnosis depends on demonstrating **capsular or vascular invasion**, which cannot be determined by FNA alone. It does not exhibit Orphan Annie eye nuclei. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common thyroid cancer:** Papillary Thyroid Carcinoma. * **Best Prognosis:** Papillary Thyroid Carcinoma. * **Route of Spread:** PTC spreads primarily via **lymphatics** (level VI nodes), whereas FTC spreads **hematogenously** (to bone/lungs). * **Risk Factor:** Prior exposure to ionizing radiation is strongly linked to PTC. * **Genetic Mutation:** Most commonly associated with **BRAF mutations** (specifically V600E) and RET/PTC rearrangements.

Question 8: What is the most common type of thyroid cancer?

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

Explanation: **Explanation:** **Papillary Thyroid Carcinoma (PTC)** is the most common type of thyroid malignancy, accounting for approximately **80–85%** of all thyroid cancers. It is typically associated with radiation exposure and has an excellent prognosis. The diagnosis is characterized by distinct nuclear features such as **Orphan Annie eye nuclei** (clear nuclei), **Psammoma bodies** (laminated calcifications), and nuclear grooves. **Analysis of Options:** * **Follicular Carcinoma (Option B):** The second most common type (approx. 10–15%). It is more prevalent in iodine-deficient areas and spreads primarily via the **hematogenous route** (to bone and lungs), unlike PTC which spreads via lymphatics. * **Medullary Carcinoma (Option C):** Accounts for about 5% of cases. It arises from the **parafollicular C-cells** and secretes **Calcitonin**. It can be sporadic or associated with MEN 2A/2B syndromes (RET proto-oncogene mutation). * **Anaplastic Carcinoma (Option D):** The rarest (<2%) but most aggressive form. It typically presents in elderly patients as a rapidly enlarging neck mass with a very poor prognosis. **High-Yield Clinical Pearls for NEET-PG:** * **Route of Spread:** Papillary = Lymphatic (most common site: Level VI nodes); Follicular = Hematogenous. * **Investigation of Choice:** FNAC is the gold standard for thyroid nodules, but it **cannot** distinguish between follicular adenoma and follicular carcinoma (requires histopathology to see capsular/vascular invasion). * **Psammoma Bodies:** Most commonly seen in Papillary CA, Meningioma, and Serous Cystadenocarcinoma of the ovary. * **Treatment:** Total thyroidectomy is the mainstay for most cases >1cm, often followed by Radioiodine (I-131) ablation.

Question 9: Swelling of the thyroid gland that does not move with deglutition is/are:

A. Retrosternal goiter
B. Riedel's goiter
C. Anaplastic carcinoma
D. All of the above (Correct Answer)

Explanation: **Explanation:** The hallmark clinical sign of a thyroid swelling is that it **moves with deglutition** (swallowing). This occurs because the thyroid gland is enclosed by the **pretracheal fascia**, which attaches the gland to the laryngeal cartilages and the hyoid bone. When these structures move upward during swallowing, the thyroid moves with them. However, certain conditions can prevent this movement: 1. **Retrosternal Goiter (Option A):** When a goiter extends significantly into the mediastinum (thoracic inlet), it can become "wedged" or "impacted" behind the sternum. The bony cage of the thoracic inlet restricts the upward excursion of the mass during swallowing. 2. **Riedel’s Thyroiditis/Goiter (Option B):** This is a rare chronic inflammatory condition characterized by dense, "woody" fibrosis. The fibrosis extends beyond the thyroid capsule to involve adjacent structures like the strap muscles, trachea, and carotid sheath, effectively "tethering" the gland and preventing movement. 3. **Anaplastic Carcinoma (Option C):** This is a highly aggressive malignancy. It frequently exhibits extrathyroidal extension, infiltrating surrounding muscles, nerves, and fascia. This local invasion causes the gland to become fixed to the neck structures. **Clinical Pearls for NEET-PG:** * **Thyroglossal Cyst:** Moves with deglutition AND **protrusion of the tongue** (due to its attachment to the hyoid bone via the tract). * **Pemberton’s Sign:** Seen in retrosternal goiters; raising the arms above the head causes facial congestion and respiratory distress due to thoracic inlet obstruction. * **Hard/Woody Thyroid:** Differential includes Riedel’s Thyroiditis and Anaplastic Carcinoma. Riedel’s is typically seen in younger patients, while Anaplastic is seen in the elderly.

Question 10: What is the most common subtype of thyroid cancer?

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

Explanation: **Explanation:** **Papillary Thyroid Carcinoma (PTC)** is the most common subtype of thyroid cancer, accounting for approximately **80–85%** of all thyroid malignancies. It is associated with exposure to ionizing radiation and generally carries an excellent prognosis. The diagnosis is characteristically made via Fine Needle Aspiration Cytology (FNAC), showing pathognomonic nuclear features such as **Orphan Annie eye nuclei** (clear nuclei), **Psammoma bodies** (laminated calcifications), and nuclear grooves. **Analysis of Incorrect Options:** * **Follicular Carcinoma (Option C):** The second most common subtype (approx. 10%). Unlike PTC, it spreads hematogenously (to bone and lungs) and cannot be diagnosed by FNAC alone, as it requires histological evidence of capsular or vascular invasion. * **Medullary Carcinoma (Option A):** Accounts for about 5% of cases. It arises from **Parafollicular C-cells** and secretes Calcitonin. It is associated with MEN 2A and 2B syndromes. * **Anaplastic Carcinoma (Option D):** The rarest (<2%) but most aggressive form. It typically presents in elderly patients as a rapidly enlarging neck mass with a very poor prognosis. **High-Yield Clinical Pearls for NEET-PG:** * **Route of Spread:** Papillary spreads via **lymphatics** (Level VI nodes first); Follicular spreads via **blood**. * **Investigation of Choice:** FNAC is the gold standard for thyroid nodules (except for Follicular CA). * **Prognostic Scoring:** AMES and MACIS scores are used specifically for Papillary carcinoma. * **Treatment:** Total thyroidectomy followed by Radioiodine (I-131) ablation is the standard for most cases >1cm.

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Thyroid Nodules

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Thyroid Cancer

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Graves' Disease

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Pheochromocytoma

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Adrenal Incidentalomas

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Multiple Endocrine Neoplasia

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Neuroendocrine Tumors

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Intraoperative Monitoring in Endocrine Surgery

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