Pheochromocytoma — MCQs
What is the correct sequence of medication administration for pre-operative prophylaxis in pheochromocytoma?
Which of the following is a component of the classic triad used for clinical diagnosis of pheochromocytoma?
Which of the following is best for diagnosis of pheochromocytoma?
A 24-year-old lady presented with sudden onset chest pain, palpitations lasting for about 20 minutes. She says there were 3 similar episodes in the past. All the investigations were normal. What is the likely diagnosis?
A patient has a cerebellar mass, renal tumor, and a family history of similar conditions. Which of the following mutations is most likely present in the family?
Which of the following is false about pheochromocytoma?
Where is a bruit typically heard in the thyroid gland?
Which of the following statements is FALSE regarding medullary cancer of the thyroid?
Which type of thyroid carcinoma is associated with hypocalcemia?
A patient presents with secondary adrenal masses. What is the most common primary site for such metastases?
Pheochromocytoma Indian Medical PG Practice Questions and MCQs
Question 1: What is the correct sequence of medication administration for pre-operative prophylaxis in pheochromocytoma?
- A. Beta blockade followed by alpha blockade
- B. Simultaneous alpha and beta blockade
- C. Alpha blockade followed by beta blockade (Correct Answer)
- D. Alpha blockade only
Explanation: ***Alpha blockade followed by beta blockade*** - **Alpha blockade** should always be initiated first to control **hypertension** and prevent a **hypertensive crisis** during surgery. This is critical because pheochromocytoma causes excessive catecholamine release, leading to profound vasoconstriction. - **Beta blockade** is then added only after adequate alpha blockade has been achieved to control **tachycardia** and arrhythmias, preventing **unopposed alpha-adrenergic stimulation** which could paradoxically worsen hypertension. *Simultaneous alpha and beta blockade* - Administering both simultaneously is dangerous because **beta blockade** can mask the effects of inadequate alpha blockade. - This can lead to **unopposed alpha-adrenergic stimulation** after beta blockade, causing severe **vasoconstriction** and hypertensive crisis. *Beta blockade followed by alpha blockade* - Initiating with **beta blockade** without prior **alpha blockade** is absolutely contraindicated in pheochromocytoma. - This can lead to severe and potentially fatal **hypertension** due to **unopposed alpha-adrenergic stimulation** as beta blockade prevents vasodilation. *Alpha blockade only* - While essential for initial management, **alpha blockade alone** might not fully control all symptoms, especially **tachycardia** and **arrhythmias** caused by high circulating catecholamine levels. - Adding a **beta blocker** after achieving adequate alpha blockade helps in controlling these cardiac effects, optimizing patient preparation for surgery.
Question 2: Which of the following is a component of the classic triad used for clinical diagnosis of pheochromocytoma?
- A. Hyperkalemia
- B. Hypertension
- C. Headache (Correct Answer)
- D. Bradycardia
Explanation: ***Headache*** - **Headache** is a key symptom in the classic triad for pheochromocytoma, caused by the **vasoconstrictive effects** of catecholamine surges. - The other two components of the classic triad are **palpitations** and **sweating**. *Hyperkalemia* - **Hyperkalemia** is not a typical manifestation of pheochromocytoma; rather, these tumors produce **catecholamines** that can lead to hyperglycemia. - Mineralocorticoid excess (e.g., in aldosteronism) is more commonly associated with electrolyte imbalances like hyperkalemia or hypokalemia. *Hypertension* - While **hypertension** is a hallmark feature of pheochromocytoma, it is a general sign rather than one of the specific three components of the classic clinical triad used for initial diagnostic suspicion. - The classic triad focuses on the most prominent and specific symptoms that suggest a **catecholamine-secreting tumor**. *Bradycardia* - **Bradycardia** is contrary to the expected cardiovascular effects of pheochromocytoma, which typically causes **tachycardia** (palpitations) due to excessive catecholamine release. - Catecholamines, such as **epinephrine** and **norepinephrine**, increase heart rate and myocardial contractility.
Question 3: Which of the following is best for diagnosis of pheochromocytoma?
- A. 24-hour Urinary Hydroxy indole acetic acid
- B. 24-hour urinary Vanillyl Mandelic acid
- C. 24-hour Urinary Hydroxy tryptamine
- D. 24-hour urinary Fractionated Metanephrine (Correct Answer)
Explanation: ***24-hour urinary Fractionated Metanephrine*** - This test measures the **metabolites of catecholamines** (epinephrine and norepinephrine), which are continuously produced by pheochromocytomas [1]. - As metanephrines are released continuously rather than episodically, their measurement in a 24-hour urine collection provides the **highest sensitivity and specificity** for diagnosing pheochromocytoma. *24-hour Urinary Hydroxy indole acetic acid* - This is a metabolite of **serotonin**, which is relevant to conditions like **carcinoid syndrome**, not pheochromocytoma. - Elevated levels would indicate a serotonin-producing tumor, not a catecholamine-producing tumor. *24-hour urinary Vanillyl Mandelic acid* - While VMA is a metabolite of both epinephrine and norepinephrine, it is a less specific and sensitive marker than fractionated metanephrines for pheochromocytoma. - Its measurement can be affected by various medications and dietary factors, leading to a higher rate of false positives and negatives compared to metanephrines. *24-hour Urinary Hydroxy tryptamine* - This refers to **serotonin**, which is not directly relevant to the diagnosis of pheochromocytoma. - Elevated levels would point towards conditions involving serotonin metabolism, such as carcinoid tumors.
Question 4: A 24-year-old lady presented with sudden onset chest pain, palpitations lasting for about 20 minutes. She says there were 3 similar episodes in the past. All the investigations were normal. What is the likely diagnosis?
- A. Post-traumatic stress disorder
- B. Acute psychosis
- C. Panic attack (Correct Answer)
- D. Mania
Explanation: ***Panic attack*** - The sudden onset of **chest pain** and **palpitations** in a young woman, lasting for a brief period (20 minutes), and occurring in recurrent episodes with all investigations being normal, are classic signs of a **panic attack**. - Panic attacks frequently mimic cardiac events, but the absence of organic findings despite recurrent episodes points towards a psychological origin. *Post-traumatic stress disorder* - While PTSD can involve symptoms of anxiety and panic, it is specifically triggered by a **traumatic event** and typically includes re-experiencing the trauma, avoidance, and hyperarousal, none of which are described here. - The patient's presentation primarily focuses on sudden physical symptoms rather than a direct link to past trauma or pervasive fear. *Acute psychosis* - Acute psychosis involves a severe break from reality, characterized by **hallucinations**, **delusions**, or disorganized thought and behavior, which are not present in this scenario. - The symptoms described are more consistent with an anxiety disorder rather than a thought disorder. *Mania* - Mania is a state of elevated mood, increased energy, and often includes symptoms like **reduced need for sleep**, **racing thoughts**, and **impulsive behavior**, which are not described in this patient's presentation. - The core symptoms are acute physical sensations of fear and discomfort, not sustained euphoria or grandiosity.
Question 5: A patient has a cerebellar mass, renal tumor, and a family history of similar conditions. Which of the following mutations is most likely present in the family?
- A. VHL (Correct Answer)
- B. Neurofibromatosis (NF1)
- C. Tuberous Sclerosis Complex (TSC)
- D. Li-Fraumeni syndrome
Explanation: ***VHL*** - **Von Hippel-Lindau (VHL) disease** is an inherited disorder characterized by the development of tumors and cysts in various parts of the body, including **hemangioblastomas** in the cerebellum and retina, **renal cell carcinomas**, and pheochromocytomas [1]. - The combination of a **cerebellar mass**, renal tumor, and a family history strongly points to VHL disease, which is caused by a germline mutation in the **VHL tumor suppressor gene** [1]. *Neurofibromatosis (NF1)* - **Neurofibromatosis type 1 (NF1)** typically presents with multiple neurofibromas, **café-au-lait spots**, optic pathway gliomas, and Lisch nodules in the iris. - While NF1 can cause tumors, the specific combination of a cerebellar mass and renal tumor is not typical of NF1, and the characteristic skin findings are not mentioned. *Tuberous Sclerosis Complex (TSC)* - **Tuberous Sclerosis Complex (TSC)** is characterized by the growth of benign tumors in the brain (e.g., **subependymal giant cell astrocytomas**), kidneys (e.g., **angiomyolipomas**), heart, lungs, and skin (e.g., facial angiofibromas) [2]. - While TSC can involve brain and kidney tumors, the typical brain tumors are different (astrocytomas vs. hemangioblastomas), and hemangioblastomas are not a common feature of TSC [2]. *Li-Fraumeni syndrome* - **Li-Fraumeni syndrome** is a rare inherited cancer predisposition syndrome characterized by a high risk of developing various cancers, including **sarcomas**, breast cancer, brain tumors (often astrocytomas or medulloblastomas), and adrenocortical carcinoma. - While brain tumors are part of Li-Fraumeni syndrome, renal cell carcinoma is not a primary feature, and the classic cerebellar hemangioblastoma is not typical for this syndrome. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 724-727. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1318-1319.
Question 6: Which of the following is false about pheochromocytoma?
- A. Surgery is the treatment of choice
- B. VMA (vanillylmandelic acid) is a diagnostic test
- C. Propranolol is the preferred drug for hypertension control (Correct Answer)
- D. Catecholamines are a diagnostic test
- E. Most pheochromocytomas are benign
Explanation: ***Propranolol is the preferred drug for hypertension control*** - Propranolol, a **beta-blocker**, is generally contraindicated as monotherapy in pheochromocytoma because blocking beta-receptors unopposed can lead to a **hypertensive crisis** due to unopposed alpha-adrenergic vasoconstriction. - **Alpha-blockers** (e.g., phenoxybenzamine) are the first-line agents for hypertension control, followed by beta-blockers once adequate alpha-blockade is established. *Surgery is the treatment of choice* - **Surgical resection** of the tumor is indeed the definitive treatment for pheochromocytoma once the patient has been appropriately prepared with alpha-blockade. - This approach aims to remove the source of excessive catecholamine production and resolve the associated symptoms. *VMA (vanillylmandelic acid) is a diagnostic test* - **VMA** is a metabolic breakdown product of catecholamines, and its measurement in a **24-hour urine collection** is a long-standing method for diagnosing pheochromocytoma. - Elevated VMA levels indicate overproduction of catecholamines, which is characteristic of the tumor. *Catecholamines are a diagnostic test* - Measuring **plasma free metanephrines** and **24-hour urinary fractionated metanephrines** (which are methylated metabolites of catecholamines) are highly sensitive and specific diagnostic tests for pheochromocytoma. - Elevated levels confirm the excessive secretion of these hormones by the tumor. *Most pheochromocytomas are benign* - Approximately **90% of pheochromocytomas are benign**, with only about 10% being malignant. - The **"rule of 10s"** is a helpful mnemonic: 10% bilateral, 10% extra-adrenal, 10% malignant, 10% familial, and 10% occur in children.
Question 7: 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 8: 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 9: 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 10: 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.
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