Endocrine Pathology Practice Questions

Q: What is true about adrenal pheochromocytoma?

Bilateral in 10% of cases. Pheochromocytoma is a catecholamine-secreting tumor arising from the chromaffin cells of the adrenal medulla. It is famously known as the **"10% tumor,"** a rule that forms the basis for answering most clinical questions on this topic. ### **Explanation of Options** * **Correct Answer (C):** In sporadic cases, pheochromocytoma is **bilateral in approximately 10%** of patients. However, if the tumor is associated with familial syndromes (like MEN 2A, MEN 2B, or VHL), the incidence of bilaterality increases significantly (up to 50-80%). * **A is Incorrect:** These tumors are **Chromaffin positive**. They are derived from the embryonic neural crest and contain cells that stain dark with chromium salts due to the oxidation of stored catecholamines. * **B is Incorrect:** Approximately **10% are malignant**. Malignancy is not determined by histology but by the presence of metastases to non-chromaffin sites (e.g., bone, liver, lungs). * **D is Incorrect:** While 90% of sporadic cases are unilateral, the option "Unilateral" is a general description rather than a defining characteristic compared to the classic "Rule of 10" tested in Option C. ### **High-Yield Clinical Pearls for NEET-PG** * **The Rule of 10s:** 10% Bilateral, 10% Malignant, 10% Extra-adrenal (Paragangliomas), 10% Pediatric, and 10% Familial (though modern genetics suggests familial cases may be as high as 30-35%). * **Clinical Triad:** Episodic headache, sweating (diaphoresis), and palpitations. * **Diagnosis:** Best initial screening test is **24-hour urinary fractionated metanephrines** or plasma free metanephrines. * **Pre-operative Management:** Always **Alpha-blockade first** (e.g., Phenoxybenzamine) for 10-14 days followed by Beta-blockade to prevent a hypertensive crisis. * **Localization:** **MIBG Scan** (I-123) is highly specific for locating extra-adrenal or metastatic tumors.

Q: In phaeochromocytoma, what substance is found in increased amounts in the urine?

Vanillylmandelic acid (VMA). ### Explanation **1. Why Vanillylmandelic acid (VMA) is correct:** Pheochromocytoma is a catecholamine-secreting tumor derived from the chromaffin cells of the adrenal medulla [1]. These tumors overproduce epinephrine and norepinephrine. In the body, catecholamines are metabolized by two primary enzymes: **Monoamine oxidase (MAO)** and **Catechol-O-methyltransferase (COMT)**. The end-stage metabolic byproduct of both epinephrine and norepinephrine is **Vanillylmandelic acid (VMA)**. Consequently, elevated urinary levels of VMA (and metanephrines) serve as critical diagnostic markers for this condition [1]. **2. Why the other options are incorrect:** * **5-Hydroxyindoleacetic acid (HIAA):** This is the primary metabolite of **serotonin**. Elevated urinary 5-HIAA is the hallmark diagnostic marker for **Carcinoid Syndrome**, not pheochromocytoma. * **Options C and D:** These are incorrect because VMA and HIAA represent distinct metabolic pathways (catecholamine vs. serotonin metabolism) associated with different neuroendocrine tumors. **3. NEET-PG High-Yield Clinical Pearls:** * **Rule of 10s:** Pheochromocytoma is 10% bilateral, 10% malignant, 10% pediatric, 10% extra-adrenal (Paraganglioma), and 10% familial. * **Best Screening Test:** 24-hour urinary fractionated **metanephrines** (more sensitive than VMA). * **Histology:** Characterized by **Zellballen patterns** (nests of cells surrounded by a vascular stroma) [1]. * **Associated Syndromes:** MEN 2A, MEN 2B, von Hippel-Lindau (VHL), and Neurofibromatosis type 1 (NF1). * **Clinical Triad:** Episodic headache, sweating (diaphoresis), and tachycardia/palpitations in a hypertensive patient [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 419-420. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1138-1139.

Q: Which of the following immunoglobulin is characteristic of LATS (Long-Acting Thyroid Stimulator)?

IgG. **Explanation:** **1. Why IgG is the Correct Answer:** Long-Acting Thyroid Stimulator (LATS) is a historical term for **Thyroid Stimulating Immunoglobulins (TSI)**, which are the hallmark of **Graves' Disease**. These are autoantibodies directed against the TSH receptors on the thyroid follicular cells. Structurally, these antibodies belong to the **IgG class**. Unlike TSH, which has a short half-life, LATS (IgG) has a much longer duration of action, leading to persistent stimulation of the thyroid gland and subsequent hyperthyroidism. **2. Why Other Options are Incorrect:** * **IgM:** This is typically the first antibody produced in an acute immune response and exists as a pentamer. It is not associated with the chronic autoimmune stimulation seen in Graves' disease. * **Glycoprotein:** While TSH (the natural hormone) is a glycoprotein, LATS is an antibody (protein). This option confuses the hormone with the antibody that mimics it. * **IgA:** This immunoglobulin is primarily involved in mucosal immunity (secretory IgA) and is not the mediator of systemic autoimmune thyroiditis. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** LATS/TSI acts as an **agonist** at the TSH receptor, stimulating the cAMP pathway. * **Placental Transfer:** Because LATS is an **IgG**, it can cross the placenta. This explains why infants born to mothers with Graves' disease may suffer from **Neonatal Thyrotoxicosis**. * **Diagnosis:** While LATS was the term used in early bioassays, modern clinical practice uses **TRAb (TSH Receptor Antibody)** assays. * **Type of Hypersensitivity:** Graves' disease is a classic example of **Type II Hypersensitivity** (Antibody-mediated cellular dysfunction).

Q: What is the distinguishing feature of multiple endocrine neoplasia 2B (MEN 2B) from multiple endocrine neoplasia 2A (MEN 2A)?

Mucosal and gastrointestinal neuromas. **Explanation:** The Multiple Endocrine Neoplasia (MEN) syndromes are autosomal dominant conditions caused by germline mutations. Both MEN 2A and MEN 2B are caused by mutations in the **RET proto-oncogene**, but they are distinguished by their specific clinical constellations [1]. **1. Why Option D is correct:** The presence of **mucosal neuromas** (typically on the tongue, lips, and eyelids) and **gastrointestinal ganglioneuromatosis** (leading to megacolon) is the hallmark of **MEN 2B** [1]. Additionally, MEN 2B patients characteristically exhibit a **Marfanoid habitus** (long limbs, joint laxity) [1]. These features are entirely absent in MEN 2A. **2. Why the other options are incorrect:** * **Options A & B (Medullary Thyroid Carcinoma and Pheochromocytoma):** These are common to **both** MEN 2A and MEN 2B [1]. In fact, MTC occurs in nearly 100% of patients in both syndromes, often being more aggressive in MEN 2B. * **Option C (Parathyroid Hyperplasia):** This is a key component of **MEN 2A** (occurring in 20-30% of cases) but is notably **absent** in MEN 2B [1]. **High-Yield Clinical Pearls for NEET-PG:** * **MEN 1 (Wermer Syndrome):** 3 Ps — **P**ituitary, **P**arathyroid, **P**ancreas. * **MEN 2A (Sipple Syndrome):** 2 Ps — **P**heochromocytoma, **P**arathyroid + MTC [1]. * **MEN 2B:** 1 P — **P**heochromocytoma + MTC + Neuromas/Marfanoid habitus [1]. * **Prophylactic Thyroidectomy:** Recommended in both MEN 2A and 2B due to the inevitable risk of MTC; however, it is performed much earlier in MEN 2B (often in infancy) due to higher virulence. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1137.

Question 1

Which type of diabetes is associated with HLA?

Accepted Answer

Type I diabetes

Answer

Type II diabetes

Answer

Malnutrition-related diabetes

Answer

Gestational diabetes

Question 2

What is true about adrenal pheochromocytoma?

Accepted Answer

Bilateral in 10% of cases

Answer

Chromaffin negative

Answer

Mostly malignant

Answer

Unilateral

Question 3

Acidophil stem cell tumors present with all of the following features except?

Accepted Answer

Thyrotoxicosis

Answer

Hypogonadism

Answer

Galactorrhea

Answer

Acromegaly

Question 4

Which of the following is FALSE regarding papillary carcinoma of the thyroid?

Accepted Answer

It has the best prognosis among all thyroid cancers.

Answer

PAX 8 mutation is associated with it.

Answer

Fine-needle aspiration cytology (FNAC) is the investigation of choice.

Answer

It can spread via hematogenous routes.

Question 5

All of the following are histological features of follicular carcinoma, except?

Accepted Answer

Intranuclear grooves and nuclear pseudo-inclusions

Answer

Capsular and vascular invasion

Answer

Uniform cells forming repetitive follicular pattern

Answer

Huhle cell variant present

Question 6

In phaeochromocytoma, what substance is found in increased amounts in the urine?

Accepted Answer

Vanillylmandelic acid (VMA)

Answer

5-Hydroxyindoleacetic acid (HIAA)

Answer

Both VMA and HIAA

Answer

Neither VMA nor HIAA

Question 7

Which of the following immunoglobulin is characteristic of LATS (Long-Acting Thyroid Stimulator)?

Accepted Answer

IgG

Answer

IgM

Answer

Glycoprotein

Answer

IgA

Question 8

Oncocytes are found in all of the following locations except?

Accepted Answer

Pineal gland

Answer

Thyroid

Answer

Pancreas

Answer

Pituitary

Question 9

What is the distinguishing feature of multiple endocrine neoplasia 2B (MEN 2B) from multiple endocrine neoplasia 2A (MEN 2A)?

Accepted Answer

Mucosal and gastrointestinal neuromas

Answer

Medullary thyroid carcinoma

Answer

Pheochromocytoma

Answer

Parathyroid hyperplasia

Question 10

Metastasis in the thyroid gland most commonly originates from which primary carcinoma?

Accepted Answer

Breast

Answer

Testis

Answer

Prostate

Answer

Lungs

Endocrine Pathology — MCQs

Endocrine Pathology — MCQs

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