Endocrine Surgery Practice Questions

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.

Q: A 52-year-old female presents with symptoms of pheochromocytoma and also has a thyroid carcinoma. What type of thyroid carcinoma does she likely have?

Medullary. **Explanation:** The correct answer is **Medullary Thyroid Carcinoma (MTC)**. This clinical presentation is a classic description of **Multiple Endocrine Neoplasia (MEN) Type 2** syndromes. **Why Medullary is correct:** The association of Pheochromocytoma and Thyroid Carcinoma is the hallmark of **MEN 2A (Sipple Syndrome)** and **MEN 2B**. * **MEN 2A:** Medullary Thyroid Carcinoma (100%), Pheochromocytoma (50%), and Parathyroid Hyperplasia (20%). * **MEN 2B:** Medullary Thyroid Carcinoma, Pheochromocytoma, Marfanoid habitus, and Mucosal neuromas. MTC arises from the parafollicular C-cells (which produce calcitonin) and is the only thyroid cancer linked to these genetic syndromes via the **RET proto-oncogene**. **Why other options are incorrect:** * **Papillary Carcinoma (D):** The most common thyroid cancer, but it is associated with radiation exposure and *not* with pheochromocytoma. * **Follicular Carcinoma (C):** Associated with iodine deficiency and hematogenous spread; it does not occur as part of MEN syndromes. * **Anaplastic Carcinoma (A):** A highly aggressive, undifferentiated tumor seen in elderly patients, unrelated to catecholamine-secreting tumors. **High-Yield Clinical Pearls for NEET-PG:** 1. **Rule of Surgery:** In a patient with both MTC and Pheochromocytoma, **always operate on the Pheochromocytoma first** to prevent a hypertensive crisis during thyroid surgery. 2. **Screening:** All patients with MTC should be screened for the **RET mutation** and co-existing pheochromocytoma (via urinary/plasma metanephrines). 3. **Tumor Marker:** Calcitonin is the specific marker for MTC diagnosis and post-operative surveillance. 4. **Prophylaxis:** Total thyroidectomy is recommended for family members carrying the RET mutation.

Q: All are true about pheochromocytoma, except:

90% are malignant. **Explanation:** Pheochromocytoma is a catecholamine-secreting tumor arising from the chromaffin cells of the adrenal medulla. The correct answer is **Option A** because it follows the classic **"Rule of 10s,"** which states that only **10% of pheochromocytomas are malignant**, while 90% are benign. **Analysis of Options:** * **Option A (Incorrect Statement/Correct Answer):** As per the Rule of 10s, 10% are malignant, 10% are bilateral, 10% are extra-adrenal, and 10% occur in children. * **Option B (True):** Approximately 95% of these tumors occur within the abdomen (90% in the adrenal medulla and the remainder in extra-adrenal sites like the Organ of Zuckerkandl). * **Option C (True):** These tumors characteristically secrete catecholamines (Norepinephrine > Epinephrine), leading to the classic triad of episodic headache, sweating, and tachycardia. * **Option D (True):** Extra-adrenal pheochromocytomas (paragangliomas) arise from the sympathetic ganglion chain. **NEET-PG High-Yield Clinical Pearls:** 1. **Diagnosis:** The most sensitive initial screening test is **plasma free metanephrines**. The most specific test is **24-hour urinary metanephrines/catecholamines**. 2. **Localization:** CT/MRI are first-line. For functional localization (especially in extra-adrenal or metastatic cases), **123I-MIBG scan** or **68Ga-DOTATATE PET/CT** is used. 3. **Pre-operative Management:** Always follow the sequence: **Alpha-blockade first** (e.g., Phenoxybenzamine) for 7–14 days, followed by **Beta-blockade** to prevent a hypertensive crisis. 4. **Genetic Associations:** Frequently associated with **MEN 2A/2B**, von Hippel-Lindau (VHL) syndrome, and Neurofibromatosis type 1 (NF1).

Question 1

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 2

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 3

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 4

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 5

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 6

How is pheochromocytoma localized?

Accepted Answer

CT scan

Answer

Clinical examination

Answer

Vanillylmandelic acid (VMA) excretion

Answer

X-ray

Question 7

A 52-year-old female presents with symptoms of pheochromocytoma and also has a thyroid carcinoma. What type of thyroid carcinoma does she likely have?

Accepted Answer

Medullary

Answer

Anaplastic

Answer

Follicular

Answer

Papillary

Question 8

Which of the following is an unusual presentation of papillary carcinoma of the thyroid?

Accepted Answer

Single nodule with local lymph node enlargement

Answer

Diffuse nodular swelling

Answer

Only lymphadenopathy

Answer

Hormonal disturbance

Question 9

All are true about pheochromocytoma, except:

Accepted Answer

90% are malignant

Answer

95% occur in the abdomen

Answer

They secrete catecholamines

Answer

They arise from sympathetic ganglions

Question 10

Which of the following statements are true regarding a solitary thyroid nodule?

Accepted Answer

Thyroid-associated-antibodies (THR-Ab) are present

Answer

The nodule is lined by columnar epithelium

Answer

It represents diffuse hyperplasia of the thyroid

Answer

It is common in females

Endocrine Surgery — MCQs

Endocrine Surgery — MCQs

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