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?
Which one of the following imaging modalities is most sensitive for localizing extra-adrenal pheochromocytoma?
Where is a bruit typically heard in the thyroid gland?
Thyroxine is used in the treatment of which thyroid cancer?
During bilateral adrenalectomy, what is the appropriate timing for intra-operative hydrocortisone administration?
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: Which one of the following imaging modalities is most sensitive for localizing extra-adrenal pheochromocytoma?
- A. USG
- B. MRI
- C. MIBG scan
- D. 68Ga-DOTATATE PET/CT (Correct Answer)
Explanation: ***68Ga-DOTATATE PET/CT*** - **68Ga-DOTATATE PET/CT** is highly sensitive for detecting **neuroendocrine tumors**, including pheochromocytomas and paragangliomas, due to its affinity for **somatostatin receptors** which are overexpressed on these cells. - This modality offers superior sensitivity in localizing both adrenal and **extra-adrenal pheochromocytomas**, particularly in cases of metastatic disease or multifocal lesions. *USG* - **Ultrasound (USG)** has limited utility for localizing **extra-adrenal pheochromocytomas**, especially if they are small, located in less accessible anatomical sites, or obscured by bowel gas. - While useful for initial screening of adrenal masses, its sensitivity for **extra-adrenal disease** is low. *MRI* - **MRI** is a valuable imaging modality for pheochromocytoma localization, offering good soft tissue contrast, but its overall sensitivity for detecting **extra-adrenal lesions** may be surpassed by more specific functional imaging techniques like 68Ga-DOTATATE PET/CT. - It is particularly useful for assessing the extent of disease and anatomical proximity to vital structures once a lesion is identified, but less sensitive for identifying occult **extra-adrenal tumors**. *MIBG scan* - **MIBG scintigraphy** relies on the uptake of a chemical analog of norepinephrine by **sympathetic neurosecretory cells**, making it useful for detecting pheochromocytomas. - However, its sensitivity in detecting **extra-adrenal pheochromocytomas** and metastatic disease is generally lower compared to 68Ga-DOTATATE PET/CT, particularly for certain genetic subtypes.
Question 8: 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 9: Thyroxine is used in the treatment of which thyroid cancer?
- A. Medullary
- B. Radiation induced
- C. Anaplastic
- D. Papillary (Correct Answer)
Explanation: **Explanation:** The correct answer is **Papillary Thyroid Carcinoma (PTC)**. **Why Papillary is Correct:** Papillary and Follicular thyroid cancers are **Differentiated Thyroid Cancers (DTC)**. These tumor cells retain receptors for **Thyroid Stimulating Hormone (TSH)**. TSH acts as a growth factor for these cells; elevated levels can promote tumor recurrence or progression. By administering exogenous **Thyroxine (L-Thyroxine)** in supra-physiological doses, we initiate a negative feedback loop that suppresses pituitary TSH secretion. This "TSH Suppression Therapy" deprives the residual cancer cells of their growth stimulus, thereby reducing recurrence rates and improving survival. **Why other options are incorrect:** * **Medullary Thyroid Cancer (MTC):** Arises from parafollicular C-cells (which produce calcitonin), not follicular cells. These cells do not have TSH receptors; therefore, TSH suppression with thyroxine has no therapeutic effect on the tumor itself. * **Anaplastic Thyroid Cancer:** This is an undifferentiated, highly aggressive tumor. The cells have lost all functional characteristics of normal thyroid tissue, including TSH receptors, making thyroxine therapy ineffective. * **Radiation-induced:** While radiation is a major risk factor for Papillary carcinoma, the term describes the etiology rather than the pathological type. The treatment depends on the resulting histology (usually Papillary). **High-Yield Clinical Pearls for NEET-PG:** * **Target TSH levels:** For high-risk DTC patients, the target TSH is usually **<0.1 mU/L**. For low-risk patients, it is **0.1–0.5 mU/L**. * **Side Effects:** Long-term TSH suppression can lead to **osteoporosis** (especially in post-menopausal women) and **atrial fibrillation**. * **Follow-up:** Serum **Thyroglobulin (Tg)** is used as a tumor marker for DTC follow-up after total thyroidectomy.
Question 10: During bilateral adrenalectomy, what is the appropriate timing for intra-operative hydrocortisone administration?
- A. After opening the abdomen
- B. After ligation of the left adrenal vein
- C. After ligation of the right adrenal vein
- D. After excision of both adrenal glands (Correct Answer)
Explanation: **Explanation:** The primary goal of perioperative steroid management in bilateral adrenalectomy is to prevent **acute adrenal crisis** while ensuring the body has sufficient glucocorticoids to handle surgical stress. **Why Option D is Correct:** During a bilateral adrenalectomy, the body can still produce endogenous cortisol as long as one gland (or a portion of it) remains vascularized and functional. The critical point of "surgical Addisonian state" occurs only after **both** glands have been completely devascularized or removed. Therefore, the full replacement dose of intra-operative hydrocortisone (typically 100mg IV) is administered immediately **after the excision of both adrenal glands**. This timing ensures a seamless transition from endogenous production to exogenous replacement. **Why Other Options are Incorrect:** * **Option A:** Administering steroids upon opening the abdomen is premature, as the patient’s own glands are still functioning and responding to the stress of surgery. * **Options B & C:** Ligation of only one adrenal vein (left or right) leaves the contralateral gland intact. The remaining gland is capable of maintaining physiological cortisol levels under the stimulus of ACTH; thus, replacement is not yet mandatory. **High-Yield Clinical Pearls for NEET-PG:** * **Steroid Cover:** Patients undergoing bilateral adrenalectomy require lifelong glucocorticoid and mineralocorticoid replacement. * **Post-Op Regimen:** After the initial intra-operative bolus, hydrocortisone is typically continued at 100mg every 8 hours for the first 24 hours, then tapered. * **Nelson’s Syndrome:** Watch for this post-bilateral adrenalectomy complication, characterized by a pituitary adenoma enlarging due to loss of cortisol feedback, leading to hyperpigmentation and high ACTH levels. * **Conn’s vs. Cushing’s:** In unilateral adrenalectomy for Conn’s syndrome, post-op steroids are usually not needed, whereas, in Cushing’s, they are vital due to contralateral gland suppression.
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