Endocrine Surgery Practice Questions

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.

Q: For screening of Medullary carcinoma of the thyroid, which of the following is estimated?

Serum calcitonin. **Explanation:** **Medullary Carcinoma of the Thyroid (MTC)** arises from the **Parafollicular C-cells**, which are neuroendocrine cells derived from the neural crest. These cells are responsible for the secretion of **Calcitonin**, a hormone that lowers blood calcium levels (though usually clinically insignificant in MTC). 1. **Why Serum Calcitonin is correct:** Calcitonin serves as a highly sensitive and specific **tumor marker** for MTC. It is used for initial screening, monitoring treatment response, and detecting recurrence. In cases where basal levels are borderline, a provocative test using pentagastrin or calcium infusion may be used to stimulate calcitonin release. 2. **Why other options are incorrect:** * **Serum HCG:** A marker for germ cell tumors (e.g., Choriocarcinoma) and gestational trophoblastic disease. * **Serum AFP (Alpha-fetoprotein):** A marker for Hepatocellular carcinoma and yolk sac tumors. * **Serum Calcium:** While MTC can be associated with MEN 2A (which includes Hyperparathyroidism), serum calcium itself is not a screening tool for the thyroid malignancy itself. **High-Yield Clinical Pearls for NEET-PG:** * **Carcinoembryonic Antigen (CEA):** Also elevated in MTC; useful for prognosis and monitoring but less specific than calcitonin. * **Genetics:** Approximately 25% of MTC cases are familial (MEN 2A, MEN 2B, or Familial MTC). All patients diagnosed with MTC must be screened for **RET proto-oncogene** mutations. * **Amyloid Stroma:** Histologically, MTC is characterized by polygonal cells with **amyloid deposits** (derived from pro-calcitonin) that stain with Congo Red. * **Management:** The primary treatment is **Total Thyroidectomy** with central compartment neck dissection. Unlike papillary or follicular cancers, MTC does **not** respond to Radioiodine (I-131) therapy.

Q: Which of the following tumors accounts for approximately 10% of cases?

Pheochromocytoma. **Explanation:** **Pheochromocytoma** is famously known as the **"10% Tumor"** in surgical pathology because it follows a unique rule of tens. This mnemonic is a high-yield concept for competitive exams: * 10% are bilateral. * 10% are extra-adrenal (Paragangliomas). * 10% are malignant. * 10% occur in children. * 10% are familial (though modern genetics suggests this may be higher, the "rule" remains a classic teaching point). * 10% are not associated with hypertension. **Analysis of Incorrect Options:** * **Papillary Thyroid Carcinoma (PTC):** This is the most common thyroid malignancy, accounting for **80–85%** of all thyroid cancers. It is characterized by Psammoma bodies and Orphan Annie eye nuclei. * **Follicular Thyroid Carcinoma (FTC):** This accounts for approximately **10–15%** of thyroid cancers. While close to 10%, it does not follow a multi-factorial "Rule of Tens" like Pheochromocytoma, making Option A the more definitive answer in a surgical context. * **Brown’s Tumor:** This is not a true neoplasm but a reactive bone lesion (Osteitis fibrosa cystica) caused by **hyperparathyroidism**. It occurs in a small percentage of patients with advanced hypercalcemia, but not specifically 10%. **Clinical Pearls for NEET-PG:** * **Diagnosis:** Best initial screening test is **24-hour urinary metanephrines**; most sensitive is plasma free metanephrines. * **Pre-op Management:** Always start **Alpha-blockade (Phenoxybenzamine)** before Beta-blockade to avoid a hypertensive crisis (unopposed alpha stimulation). * **Localization:** MIBG scan is used if CT/MRI is negative or to find extra-adrenal sites.

Q: Which malignancy is most likely to occur in a long-standing multinodular goitre?

Follicular Carcinoma. **Explanation:** The correct answer is **Follicular Carcinoma (Option B)**. **Why Follicular Carcinoma is correct:** The development of thyroid malignancy in a long-standing multinodular goitre (MNG) is closely linked to **iodine deficiency** and chronic TSH stimulation. In regions where MNG is endemic due to low iodine intake, **Follicular Carcinoma** is the most common malignancy observed. Chronic stimulation of follicular cells leads to hyperplasia, which can eventually undergo malignant transformation into follicular carcinoma. **Why other options are incorrect:** * **Papillary Carcinoma (Option A):** While this is the most common thyroid malignancy overall (especially in iodine-sufficient areas), it is typically associated with radiation exposure rather than long-standing MNG. * **Anaplastic Carcinoma (Option C):** Although anaplastic carcinoma often arises from a pre-existing differentiated thyroid cancer (like follicular) in an elderly patient with a long-standing goitre, it is statistically less common than the initial transformation into follicular carcinoma. * **Medullary Carcinoma (Option D):** This arises from the parafollicular C-cells and is associated with MEN 2 syndromes or sporadic mutations (RET proto-oncogene). It has no etiologic relationship with MNG or iodine deficiency. **High-Yield NEET-PG Pearls:** * **Most common thyroid cancer overall:** Papillary Carcinoma. * **Most common thyroid cancer in MNG/Iodine deficient areas:** Follicular Carcinoma. * **Route of spread:** Papillary spreads via **lymphatics**; Follicular spreads via **blood** (hematogenous). * **Orphan Annie eyes** and **Psammoma bodies** are hallmarks of Papillary Carcinoma. * **Vascular/Capsular invasion** is mandatory to diagnose Follicular Carcinoma (cannot be diagnosed by FNAC).

Q: How is pheochromocytoma localized?

CT scan. **Explanation:** The localization of pheochromocytoma is a critical step that occurs only **after** biochemical confirmation of the diagnosis. **Why CT Scan is the Correct Answer:** Once elevated catecholamines or metanephrines are confirmed, imaging is required to find the tumor. **Contrast-Enhanced CT (CECT)** of the abdomen and pelvis is the initial imaging modality of choice. It has high sensitivity (98–100%) for detecting adrenal masses, as most pheochromocytomas are >3 cm. If CT is inconclusive or if the patient is a child/pregnant woman, **MRI** is preferred (showing a characteristic "light bulb" appearance on T2-weighted images). **Analysis of Incorrect Options:** * **Clinical Examination (A):** Pheochromocytoma is the "10% tumor" and often deep-seated; it cannot be localized by physical exam. Palpation of the abdomen can actually trigger a life-threatening hypertensive crisis. * **VMA Excretion (B):** 24-hour urinary VMA or plasma metanephrines are used for **biochemical diagnosis**, not localization. They tell you the tumor exists but not where it is located. * **X-ray (D):** Plain radiographs lack the soft-tissue resolution necessary to identify adrenal or extra-adrenal masses. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s:** 10% are bilateral, 10% are malignant, 10% are pediatric, and 10% are extra-adrenal (Paragangliomas). * **Functional Imaging:** If CT/MRI are negative but biochemistry is positive, use **123I-MIBG scan** or **68Ga-DOTATATE PET/CT** to find extra-adrenal or metastatic sites. * **Pre-op Management:** Always start **Alpha-blockers** (e.g., Phenoxybenzamine) 10–14 days before surgery; Beta-blockers are added only after adequate alpha-blockade to avoid hypertensive crisis.

Question 1

Thyroxine can be given in which type of thyroid carcinoma?

Accepted Answer

Papillary

Answer

Medullary

Answer

Anaplastic

Answer

Undifferentiated

Question 2

Which of the following statements is NOT true regarding medullary carcinoma of the thyroid?

Accepted Answer

Fine needle aspiration cytology (FNAC) cannot be used for diagnosis.

Answer

Metastases to bone are osteoblastic.

Answer

Carcinoembryonic antigen is a better predictor of prognosis compared to calcitonin.

Answer

Medullary carcinomas of the thyroid are not hormone dependent.

Question 3

For screening of Medullary carcinoma of the thyroid, which of the following is estimated?

Accepted Answer

Serum calcitonin

Answer

Serum HCG

Answer

Serum AFP

Answer

Serum Calcium

Question 4

Which of the following features helps differentiate parathyroid adenoma from parathyroid hyperplasia?

Accepted Answer

Identification of hyperplasia in all four glands during surgery

Answer

Presence of excess chief cells

Answer

High levels of parathormone

Answer

Infiltration of the capsule

Question 5

A 57-year-old female presents with a one-month history of burning epigastric pain after eating, associated with a 4 kg weight loss in the past month. She also complains of severe diarrhea, with 8-10 loose stools daily. What is the most common site of this condition?

Accepted Answer

Between the head of the pancreas and the bile duct

Answer

Head of the pancreas

Answer

Tail of the pancreas

Answer

Body of the pancreas

Question 6

Which of the following tumors accounts for approximately 10% of cases?

Accepted Answer

Pheochromocytoma

Answer

Papillary Thyroid Carcinoma

Answer

Follicular Thyroid Carcinoma

Answer

Brown's Tumor

Question 7

An adrenal biopsy should be considered after ruling out which of the following conditions?

Accepted Answer

Pheochromocytoma

Answer

Adrenocortical carcinoma

Answer

Metastases

Answer

Cushing's syndrome

Question 8

Which malignancy is most likely to occur in a long-standing multinodular goitre?

Accepted Answer

Follicular Carcinoma

Answer

Papillary Carcinoma

Answer

Anaplastic Carcinoma

Answer

Medullary Carcinoma

Question 9

In the surgical management of parathyroid hyperplasia, if 3 1/2 glands are removed, what is the typical management of the remaining 1/2 gland?

Accepted Answer

Mined and inserted into the brachioradialis muscle

Answer

Left in situ to prevent injury to the recurrent laryngeal nerve

Answer

Sent for histopathological examination

Answer

Left in situ to meet the metabolic demands of the body

Question 10

How is pheochromocytoma localized?

Accepted Answer

CT scan

Answer

Clinical examination

Answer

Vanillylmandelic acid (VMA) excretion

Answer

X-ray

Endocrine Surgery — MCQs

Endocrine Surgery — MCQs

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