Endocrine Surgery Practice Questions

Q: A female patient presented with severe secretory diarrhea was diagnosed with medullary thyroid carcinoma (MTC). What is the primary treatment for MTC?

Surgery only. **Explanation:** **Medullary Thyroid Carcinoma (MTC)** arises from the **parafollicular C-cells**, which are neuroendocrine cells derived from the neural crest. These cells secrete **calcitonin**, which often serves as a tumor marker. In some cases, high levels of calcitonin or other peptides (like VIP) can cause systemic symptoms such as secretory diarrhea. 1. **Why "Surgery only" is correct:** The primary and most effective treatment for MTC is **Total Thyroidectomy with Central Neck Dissection (Level VI)**. Since MTC does not concentrate iodine and is generally resistant to conventional chemotherapy and radiation, surgical clearance is the only curative modality. If lymph nodes are clinically positive, a lateral neck dissection is also performed. 2. **Why other options are incorrect:** * **Radioiodine (I-131) ablation:** This is used for differentiated thyroid cancers (Papillary/Follicular) arising from follicular cells. Since C-cells do not take up iodine, I-131 has **no role** in MTC. * **Radiotherapy:** It is not a primary treatment and is reserved only for palliative care or local recurrence that cannot be surgically resected. * **Chemotherapy:** MTC is notoriously chemo-resistant. Targeted therapies (Tyrosine Kinase Inhibitors like **Vandetanib** or **Cabozantinib**) are used only for metastatic or progressive disease, not as primary treatment. **High-Yield Clinical Pearls for NEET-PG:** * **Screening:** All patients with MTC must be screened for **MEN 2A/2B** syndromes (specifically checking for Pheochromocytoma via urinary metanephrines before surgery). * **Genetic Testing:** *RET* proto-oncogene mutation testing is mandatory for the patient and first-degree relatives. * **Tumor Markers:** Calcitonin (for diagnosis/recurrence) and CEA (for prognosis). * **Prophylactic Surgery:** In *RET* mutation carriers, prophylactic thyroidectomy is recommended (age depends on the specific codon mutation).

Q: What is the standard surgical treatment for anaplastic carcinoma of the thyroid?

Total thyroidectomy. ### Explanation **Anaplastic Thyroid Carcinoma (ATC)** is one of the most aggressive solid tumors in humans, characterized by rapid growth and early local invasion. **Why Total Thyroidectomy is the Correct Answer:** The primary goal of surgery in ATC is **local disease control** and the prevention of airway obstruction (death by asphyxiation). If the tumor is resectable (confined to the thyroid or with minimal extrathyroidal extension), a **Total Thyroidectomy** is the standard surgical approach. It aims for an R0 or R1 resection to debulk the tumor, which improves the efficacy of adjuvant radiotherapy and chemotherapy. Even in advanced cases, surgery is often performed as a palliative measure to secure the airway. **Why Incorrect Options are Wrong:** * **A, B, & C (Hemithyroidectomy, Subtotal, and Near-total):** These procedures are oncologically inadequate for ATC. Leaving behind residual thyroid tissue increases the risk of rapid local recurrence and does not provide the necessary decompression of the trachea. In a malignancy this aggressive, anything less than a total thyroidectomy (when feasible) is considered incomplete treatment. **High-Yield Clinical Pearls for NEET-PG:** * **Presentation:** Typically presents in elderly patients (6th–7th decade) as a rapidly enlarging neck mass, often with hoarseness (RLN palsy) and dysphagia. * **Diagnosis:** Fine Needle Aspiration (FNA) may be suggestive, but **Core Needle Biopsy** or open biopsy is often required for definitive diagnosis (showing spindle, giant, or squamoid cells). * **Markers:** ATC is typically **negative for Thyroglobulin** and often loses expression of TTF-1. It may show positivity for PAX-8. * **Prognosis:** Extremely poor; the focus is often on palliative care, including tracheostomy if the tumor is unresectable. * **BRAF V600E Mutation:** Found in about 25% of cases; targeted therapy (Dabrafenib + Trametinib) is now a recognized treatment option.

Q: Which of the following is the first vein ligated during thyroidectomy?

Middle thyroid vein. In thyroid surgery, the sequence of vessel ligation is critical for both exposure and safety. ### Why the Middle Thyroid Vein is Ligated First The **middle thyroid vein** is the first vessel to be ligated during a thyroidectomy. Unlike the superior and inferior veins, the middle thyroid vein is short, wide, and runs directly lateral from the thyroid gland to the internal jugular vein (IJV). * **Surgical Rationale:** Ligating this vein early allows the surgeon to "mobilize" the thyroid gland. Once divided, the gland can be rotated medially, providing the necessary exposure to safely identify and ligate the superior and inferior poles and visualize the recurrent laryngeal nerve (RLN). ### Explanation of Incorrect Options * **A. Superior Thyroid Vein:** This is ligated as part of the superior pole dissection. It is usually addressed after mobilization has begun. * **C. Inferior Thyroid Vein:** These veins form a plexus (plexus thyroideus impar) at the lower pole. They are typically ligated later in the procedure during the dissection of the inferior pole. * **D. Thyroid Ima Vein:** This is an inconsistent anatomical variant (present in ~3–10% of people) arising from the brachiocephalic trunk or arch of aorta. While it must be ligated if present, it is not the standard first step. ### High-Yield Clinical Pearls for NEET-PG * **The "Danger" Zone:** When ligating the **superior thyroid artery**, stay **close to the gland** to avoid injuring the **external branch of the superior laryngeal nerve**. * **The "Safe" Zone:** When ligating the **inferior thyroid artery**, ligate it **away from the gland** (trunk ligation) to avoid injuring the **recurrent laryngeal nerve**. * **Kocher’s Incision:** The standard transverse collar incision used for thyroidectomy, placed two fingerbreadths above the suprasternal notch.

Q: Which type of thyroid carcinoma is most commonly associated with cervical lymphadenopathy?

Papillary carcinoma. **Explanation:** **Papillary Thyroid Carcinoma (PTC)** is the most common thyroid malignancy and is characterized by its **lymphatic route of spread**. Approximately 30–50% of patients present with clinically detectable cervical lymphadenopathy at the time of diagnosis, and microscopic nodal involvement can be found in up to 80% of cases. This predilection for regional lymph nodes (specifically Level VI/central compartment) is a hallmark of PTC. **Analysis of Incorrect Options:** * **Follicular Carcinoma:** This tumor primarily spreads via the **hematogenous route** (bloodstream). It typically metastasizes to distant sites like bones and lungs; cervical lymphadenopathy is rare (seen in <10% of cases). * **Anaplastic Carcinoma:** While it is highly aggressive and causes massive local invasion, it is characterized by rapid growth and distant metastasis. It is less "associated" with isolated cervical lymphadenopathy compared to the classic presentation of PTC. * **Medullary Carcinoma:** This tumor does spread to lymph nodes frequently (around 50%), but since Papillary carcinoma is significantly more common in the general population, PTC remains the most frequent cause of thyroid-related cervical lymphadenopathy encountered in clinical practice. **High-Yield Clinical Pearls for NEET-PG:** * **Psammoma bodies** (calcified laminations) are a characteristic histological feature of Papillary carcinoma. * **Orphan Annie eye nuclei** and **nuclear grooves** are diagnostic hallmarks of PTC. * **Prognosis:** PTC has an excellent prognosis despite frequent nodal involvement. * **Risk Factor:** Prior exposure to ionizing radiation is the most significant risk factor for PTC.

Q: A patient has undergone total thyroidectomy for papillary carcinoma of the thyroid. What is the marker for follow-up of such a patient?

Thyroglobulin. **Explanation:** **Thyroglobulin (Tg)** is the correct answer because it is a protein produced exclusively by follicular cells of the thyroid gland. In a patient who has undergone **total thyroidectomy** (and often radioactive iodine ablation), there should be no remaining thyroid tissue. Therefore, serum thyroglobulin levels should ideally be undetectable. If Tg levels become detectable or rise during follow-up, it serves as a highly sensitive and specific biochemical marker for **recurrent or metastatic disease** in differentiated thyroid cancers (Papillary and Follicular). **Analysis of Incorrect Options:** * **Calcitonin (B):** This is the tumor marker for **Medullary Thyroid Carcinoma (MTC)**, as it is secreted by the parafollicular C-cells. It has no role in monitoring papillary carcinoma. * **TSH (C):** While TSH levels are monitored to ensure adequate suppressive thyroxine therapy (to prevent TSH-mediated stimulation of potential micrometastases), TSH itself is not a marker of the tumor burden or recurrence. * **Serum Iodine Levels (D):** These levels do not correlate with the presence or recurrence of thyroid malignancy. **High-Yield Clinical Pearls for NEET-PG:** * **Anti-thyroglobulin antibodies (TgAb):** Always measure TgAb alongside Tg. If antibodies are present, they can falsely lower the Tg reading, making the marker unreliable. * **Stimulated Tg:** Tg is most sensitive when TSH is high (either by stopping thyroxine or giving recombinant TSH). * **Whole Body Scan (WBS):** Often used in conjunction with Tg for initial follow-up to detect iodine-avid metastases. * **Papillary Carcinoma:** The most common thyroid cancer, characterized by **Psammoma bodies** and **Orphan Annie eye nuclei** on histology.

Q: Parathyroid auto-transplantation is performed in which of the following muscles?

Brachioradialis. **Explanation:** Parathyroid auto-transplantation is a standard procedure performed during total parathyroidectomy (e.g., for secondary hyperparathyroidism) or when a healthy parathyroid gland is inadvertently devascularized during thyroid surgery. **Why Brachioradialis is the Correct Answer:** The **Brachioradialis muscle** of the non-dominant forearm is the preferred site for auto-transplantation. The gland is minced into 1-mm fragments and placed into small muscular pockets. This site is chosen because: 1. **Accessibility:** It is easily accessible under local anesthesia if a recurrence occurs. 2. **Monitoring:** It allows for the **Casanova Test** (differential venous sampling). By sampling blood from both arms, clinicians can determine if recurrent hypercalcemia is due to the transplanted tissue (higher PTH in the grafted arm) or an ectopic gland in the neck/mediastinum. 3. **Safety:** It avoids the morbidity of a repeat neck exploration. **Why Other Options are Incorrect:** * **Biceps and Triceps:** While these are large muscles, they are deeper and less peripheral than the brachioradialis, making surgical re-exploration and venous sampling more complex. * **Sartorius:** This is located in the thigh. While the **Sternocleidomastoid (SCM)** is a common alternative site in the neck, the lower limb is rarely used because it lacks the ease of venous monitoring provided by the forearm. **High-Yield Clinical Pearls for NEET-PG:** * **Alternative Site:** If the forearm is not used, the **Sternocleidomastoid (SCM)** is the second most common site (often used during thyroidectomy). * **Cryopreservation:** Excess parathyroid tissue can be cryopreserved for up to 18 months if the initial graft fails. * **Indications:** Most commonly performed in **MEN 1, MEN 2A**, and **Secondary Hyperparathyroidism** (Renal Osteodystrophy). * **Success Rate:** The graft usually begins functioning within 4–6 weeks.

Q: Complications of Hemithyroidectomy include all of the following except?

Hypocalcemia. **Explanation:** The correct answer is **Hypocalcemia**. **1. Why Hypocalcemia is the correct answer:** Hypocalcemia occurs due to hypoparathyroidism, which results from the accidental removal or devascularization of the parathyroid glands. Humans typically have four parathyroid glands (two on each side). In a **hemithyroidectomy**, only one lobe of the thyroid is removed, leaving the two parathyroid glands on the contralateral side intact. These remaining glands are sufficient to maintain normal serum calcium levels. Therefore, clinically significant hypocalcemia is a complication of total or completion thyroidectomy, but not hemithyroidectomy. **2. Analysis of incorrect options:** * **Wound Hematoma:** This is a potential complication of *any* neck surgery. It is life-threatening if it causes airway compression (tension hematoma), regardless of whether the resection was unilateral or bilateral. * **Recurrent Laryngeal Nerve (RLN) Palsy:** The RLN runs in the tracheoesophageal groove on both sides. During a hemithyroidectomy, the nerve on the operative side is at risk of injury, leading to hoarseness. * **External Branch of Superior Laryngeal Nerve (EBSLN) Palsy:** This nerve travels close to the superior thyroid artery. Injury during ligation of the superior pole vessels on the operative side can occur, resulting in loss of high-pitched voice and vocal fatigue. **Clinical Pearls for NEET-PG:** * **Most common cause of hypocalcemia post-thyroidectomy:** Accidental trauma or ischemia to parathyroid glands. * **Most common nerve injured in thyroid surgery:** EBSLN (often under-diagnosed); however, RLN injury is more clinically significant. * **Emergency management of post-op hematoma:** Immediate bedside evacuation of the clot (opening the sutures) to relieve airway obstruction, followed by formal exploration in the OR.

Q: Thyroxine can be given in which type of thyroid carcinoma?

Papillary. **Explanation:** The correct answer is **Papillary Thyroid Carcinoma (PTC)**. **Why Papillary is Correct:** Papillary and Follicular carcinomas are classified as **Differentiated Thyroid Cancers (DTC)**. These tumors arise from follicular cells and often retain the physiological characteristics of normal thyroid tissue, including the expression of **TSH receptors**. TSH (Thyroid Stimulating Hormone) acts as a growth factor for these malignant cells. By administering exogenous **Thyroxine (T4)** in supraphysiological doses, we achieve **TSH suppression** via the negative feedback loop. This reduces the stimulus for tumor growth, decreases recurrence rates, and improves survival in DTC patients. **Why Other Options are Incorrect:** * **Medullary Thyroid Carcinoma (B):** This tumor arises from **Parafollicular C-cells**, which secrete calcitonin. C-cells do not possess TSH receptors; therefore, TSH suppression with Thyroxine has no therapeutic effect on tumor growth. * **Anaplastic (C) and Undifferentiated (D) Carcinoma:** These are highly aggressive, pleomorphic tumors that have lost all functional characteristics of thyroid follicular cells, including TSH receptors. They do not respond to hormonal manipulation. **NEET-PG High-Yield Pearls:** * **Target TSH Levels:** In high-risk DTC, the goal is typically TSH <0.1 mU/L. In low-risk patients, it is 0.1–0.5 mU/L. * **Monitoring:** Serum **Thyroglobulin (Tg)** is used as a tumor marker for follow-up in PTC after total thyroidectomy. * **Radioactive Iodine (RAI):** PTC also takes up RAI (I-131) because it retains the sodium-iodide symporter (NIS), unlike Medullary or Anaplastic types. * **Most Common:** Papillary is the most common thyroid cancer and has the best prognosis.

Question 1

A female patient presented with severe secretory diarrhea was diagnosed with medullary thyroid carcinoma (MTC). What is the primary treatment for MTC?

Accepted Answer

Surgery only

Answer

Surgery and Radiotherapy

Answer

Radiotherapy and Chemotherapy

Answer

Radioiodine ablation

Question 2

What is the standard surgical treatment for anaplastic carcinoma of the thyroid?

Accepted Answer

Total thyroidectomy

Answer

Hemithyroidectomy

Answer

Subtotal thyroidectomy

Answer

Near total thyroidectomy

Question 3

Which of the following is the first vein ligated during thyroidectomy?

Accepted Answer

Middle thyroid vein

Answer

Superior thyroid vein

Answer

Inferior thyroid vein

Answer

Thyroid ima vein

Question 4

Which type of thyroid carcinoma is most commonly associated with cervical lymphadenopathy?

Accepted Answer

Papillary carcinoma

Answer

Follicular carcinoma

Answer

Anaplastic carcinoma

Answer

Medullary carcinoma

Question 5

A patient has undergone total thyroidectomy for papillary carcinoma of the thyroid. What is the marker for follow-up of such a patient?

Accepted Answer

Thyroglobulin

Answer

Calcitonin

Answer

TSH

Answer

Serum iodine levels

Question 6

The principle of "Wolff-chaikoff effect" is utilized in which of the following clinical scenarios?

Accepted Answer

Administration of iodide for thyrotoxic patients before surgery

Answer

Administration of iodide for thyrotoxic patients after surgery

Answer

Stimulation of hormone synthesis

Answer

Increased vascularity of the thyroid gland

Question 7

Parathyroid auto-transplantation is performed in which of the following muscles?

Accepted Answer

Brachioradialis

Answer

Biceps

Answer

Triceps

Answer

Sartorius

Question 8

Complications of Hemithyroidectomy include all of the following except?

Accepted Answer

Hypocalcemia

Answer

Wound hematoma

Answer

Recurrent laryngeal nerve palsy

Answer

External branch of superior laryngeal nerve palsy

Question 9

The triad originally described for Zollinger-Ellison syndrome is characterized by?

Accepted Answer

Peptic ulceration, gastric hypersecretion, non-beta cell tumor

Answer

Peptic ulceration, gastric hypersecretion, beta cell tumor

Answer

Peptic ulceration, achlorhydria, non-beta cell tumor

Answer

Peptic ulceration, achlorhydria, beta cell tumor

Question 10

Thyroxine can be given in which type of thyroid carcinoma?

Accepted Answer

Papillary

Answer

Medullary

Answer

Anaplastic

Answer

Undifferentiated

Endocrine Surgery — MCQs

Endocrine Surgery — MCQs

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