Endocrine Pathology Practice Questions

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: The definite diagnosis of malignancy in pheochromocytoma is based on what?

Presence of metastasis. **Explanation:** The diagnosis of malignancy in pheochromocytoma is unique because it cannot be determined by the histological appearance of the primary tumor alone [1]. **1. Why "Presence of Metastasis" is correct:** Pheochromocytoma is often referred to as the "10% tumor." Unlike most other neoplasms, there are no reliable microscopic features (like atypia or mitoses) that definitively predict clinical behavior [1]. Therefore, the **only absolute criterion** for malignancy is the presence of **metastatic spread** to non-chromaffin sites where paraganglionic tissue is not normally found, such as the liver, lungs, bone, or regional lymph nodes. **2. Why other options are incorrect:** * **Cellular and Nuclear Pleomorphism:** These features are common in many endocrine tumors (often called "endocrine atypia") and can be seen in perfectly benign pheochromocytomas. They do not correlate with biological aggressiveness. * **Mitotic Figures:** While an increased mitotic rate may be suggestive of a more aggressive tumor, it is not diagnostic of malignancy in this specific context. Even tumors with low mitotic activity can metastasize. **3. High-Yield Clinical Pearls for NEET-PG:** * **The Rule of 10s:** 10% are malignant, 10% are bilateral, 10% are extra-adrenal (paragangliomas), and 10% occur in children. (Note: Modern genetics suggest up to 25-30% may be familial). * **Zellballen Pattern:** The classic histological arrangement where tumor cells are grouped in small nests surrounded by a vascular stroma. * **PASS Score:** The *Pheochromocytoma of the Adrenal Gland Scaled Score* is used to estimate malignant potential, but metastasis remains the "gold standard" for diagnosis. * **Genetics:** Mutations in the **SDHB** gene are the strongest predictors of metastatic potential. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 419-420.

Q: Which of the following is used for measurement in diabetes mellitus?

HbA1c. **Explanation:** **Correct Answer: D. HbA1c** HbA1c (Glycated Hemoglobin) is the gold standard for monitoring long-term glycemic control in Diabetes Mellitus [1]. It is formed by the **non-enzymatic glycosylation** of the N-terminal valine of the hemoglobin beta chain. Since the average lifespan of a red blood cell is approximately **120 days**, HbA1c levels reflect the average blood glucose concentration over the preceding **2–3 months**. According to ADA criteria, an HbA1c value of **≥ 6.5%** is diagnostic for Diabetes Mellitus [1]. **Analysis of Incorrect Options:** * **A. HbA:** This is normal adult hemoglobin ($̑_2̒_2$), comprising about 95–97% of total hemoglobin in adults. It is not a specific marker for glucose monitoring. * **B. HbS:** This is the abnormal hemoglobin found in **Sickle Cell Anemia**, resulting from a point mutation (glutamic acid replaced by valine at the 6th position of the $̒$-chain). * **C. HbA2:** This is a minor adult hemoglobin ($̑_2̔_2$). Elevated levels (typically >3.5%) are a key diagnostic marker for **Beta-Thalassemia minor**. **High-Yield Clinical Pearls for NEET-PG:** * **Fructosamine Test:** Reflects glycemic control over the past **2–3 weeks** (useful when HbA1c is unreliable, e.g., in hemolytic anemia). * **False Low HbA1c:** Seen in conditions with shortened RBC lifespan (Hemolytic anemia, recent blood loss, or pregnancy). * **False High HbA1c:** Seen in conditions like Iron Deficiency Anemia (due to increased RBC age/structural changes). * **Target HbA1c:** For most non-pregnant adults with diabetes, the goal is **< 7%** to reduce microvascular complications. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1109-1111.

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.

Q: What is the characteristic histological feature of de Quervain's thyroiditis?

Giant cell infiltration. **Explanation:** **De Quervain’s Thyroiditis** (also known as Subacute Granulomatous Thyroiditis) is a self-limiting, inflammatory condition of the thyroid, typically following a viral upper respiratory tract infection. **Why the correct answer is right:** The hallmark of de Quervain’s thyroiditis is the **granulomatous inflammation**. The process begins with follicular destruction and colloid leakage, which triggers an intense inflammatory response. The characteristic histological finding is the presence of **multinucleated giant cells** (foreign-body type) surrounding fragments of colloid or forming organized granulomas. This "giant cell infiltration" is the most specific diagnostic feature on biopsy. **Analysis of incorrect options:** * **A. Mononuclear cell infiltration:** While lymphocytes and plasma cells are present, this is a non-specific finding seen in almost all inflammatory thyroid conditions (e.g., Hashimoto’s). * **B. Histiocytic reaction:** Although macrophages (histiocytes) are involved in forming the granuloma, the presence of fused histiocytes forming **giant cells** is the defining characteristic for this condition. * **D. Eosinophilia:** Eosinophilic infiltration is not a primary feature of de Quervain’s; it is more commonly associated with drug-induced reactions or specific rare conditions like Riedel’s thyroiditis (occasionally). **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** It is the **most common cause of a painful thyroid gland**. Look for a patient with a tender, enlarged thyroid and a high ESR. * **Etiology:** Often follows a viral prodrome (Coxsackievirus, Mumps, Adenovirus). * **Laboratory:** Characterized by a "triphasic" course (Hyperthyroidism → Hypothyroidism → Euthyroidism). * **Radioiodine Uptake (RAIU):** Classically **decreased** (low uptake) despite symptoms of thyrotoxicosis, due to follicular damage.

Question 1

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 2

Which of the following neoplasms is primary in the adrenal medulla?

Accepted Answer

Pheochromocytoma

Answer

Eosinophilic adenoma

Answer

Arrhenoblastoma

Answer

None of the above

Question 3

A 65-year-old woman with a history of multinodular goiter complains of increasing nervousness, insomnia, and heart palpitations. She has lost 9 kg (20 lb) over the past 6 months. Physical examination reveals a diffusely enlarged thyroid. There is no evidence of exophthalmos. Laboratory studies show elevated serum levels of T3 and T4. Serologic tests for antithyroid antibodies are negative. Which of the following is an important complication of this patient's endocrinopathy?

Accepted Answer

Cardiac arrhythmia

Answer

Autoimmune hepatitis

Answer

Follicular carcinoma of the thyroid

Answer

Medullary carcinoma of the thyroid

Question 4

The definite diagnosis of malignancy in pheochromocytoma is based on what?

Accepted Answer

Presence of metastasis

Answer

Cellular pleomorphism

Answer

Nuclear pleomorphism

Answer

Mitotic figures

Question 5

Which of the following organs are not affected in autoimmune polyglandular syndrome type 2?

Accepted Answer

Adrenal

Answer

Parathyroid

Answer

Thyroid

Answer

Pancreas

Question 6

Which of the following is true regarding medullary carcinoma of the thyroid?

Accepted Answer

All of the above

Answer

Arises from parafollicular cells

Answer

Amyloid in stroma

Answer

Secretes calcitonin

Question 7

Which of the following is used for measurement in diabetes mellitus?

Accepted Answer

HbA1c

Answer

HbA

Answer

HbS

Answer

HbA2

Question 8

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 9

What is the characteristic histological feature of de Quervain's thyroiditis?

Accepted Answer

Giant cell infiltration

Answer

Mononuclear cell infiltration

Answer

Histiocytic reaction

Answer

Eosinophilia

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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