Endocrine Pathology Practice Questions

Q: What is the most common site for a pheochromocytoma?

Adrenal medulla. **Explanation:** **1. Why the Adrenal Medulla is Correct:** Pheochromocytoma is a catecholamine-secreting tumor derived from **chromaffin cells**. These cells are embryologically derived from the neural crest and are primarily concentrated in the **adrenal medulla** [1]. Statistically, approximately **85% to 90%** of these tumors occur within the adrenal medulla, making it the most common site. **2. Why the Other Options are Incorrect:** * **Adrenal Cortex:** This is the outer layer of the adrenal gland derived from mesoderm. it produces steroids (cortisol, aldosterone, androgens). It does not contain chromaffin cells and therefore cannot be the site of a pheochromocytoma. * **Paravertebral Ganglion & Paraaortic-sympathetic Chain:** While these are common sites for **extra-adrenal** pheochromocytomas (also known as **paragangliomas**), they only account for about 10-15% of cases. The most famous extra-adrenal site is the Organ of Zuckerkandl, located at the bifurcation of the aorta. **3. High-Yield Clinical Pearls for NEET-PG:** * **The Rule of 10s:** Traditionally, pheochromocytoma is known as the "10% tumor": 10% are extra-adrenal, 10% are bilateral, 10% are malignant, 10% occur in children, and 10% are not associated with hypertension. (Note: Recent genetics suggest up to 25-30% may be familial). * **Zellballen Pattern:** On histology, the tumor cells are arranged in small clusters or nests surrounded by a rich vascular network. * **Diagnosis:** The best initial screening test is measuring **urinary or plasma metanephrines** (metabolites of catecholamines). * **Associated Syndromes:** MEN 2A, MEN 2B, von Hippel-Lindau (VHL) syndrome, and Neurofibromatosis type 1 (NF1). **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 418-419.

Q: In Diabetes Mellitus type II, insulin resistance develops due to which of the following mechanisms?

End organ target receptor insensitivity. **Explanation:** **Mechanism of the Correct Answer (A):** Type 2 Diabetes Mellitus (T2DM) is characterized by a dual defect: **insulin resistance** and progressive **beta-cell dysfunction** [3]. Insulin resistance refers to the decreased biological response of peripheral tissues (primarily skeletal muscle, liver, and adipose tissue) to circulating insulin. This "end-organ target receptor insensitivity" occurs due to defects in the insulin signaling pathway, most commonly involving post-receptor signaling abnormalities (e.g., impaired tyrosine kinase activity or phosphorylation of Insulin Receptor Substrates) [2]. Consequently, higher levels of insulin are required to maintain glucose homeostasis [1]. **Analysis of Incorrect Options:** * **B & C (DKA and HHS):** These are **acute metabolic complications** of diabetes, not the underlying cause of insulin resistance. DKA is more common in Type 1 DM (absolute insulin deficiency), while HHS is a hallmark of Type 2 DM (relative insulin deficiency). * **D (Genetic Predisposition):** While T2DM has a stronger genetic component than Type 1 DM, genetics is a **risk factor** or a "predisposing cause," not the physiological mechanism of resistance itself. The question asks for the specific mechanism by which resistance develops. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for measuring insulin resistance:** Hyperinsulinemic-euglycemic clamp (rarely used clinically). * **First sign of T2DM:** Post-prandial hyperglycemia. * **Key Mediator:** Free Fatty Acids (FFAs) play a crucial role in inducing insulin resistance via the "Randle Cycle" and lipotoxicity [3]. * **Clinical Marker:** Acanthosis Nigricans is a classic cutaneous marker of underlying insulin resistance.

Q: A 40-year-old female presents with fever, fatigue, and diffuse painful swelling in the midline of the neck. Fine-needle aspiration cytology (FNAC) of the swelling reveals epithelioid cells and giant cells. What is the most likely diagnosis?

Subacute thyroiditis. ### **Explanation** The clinical presentation of a **painful, tender thyroid swelling** following a viral prodrome (fever, fatigue) is the classic hallmark of **Subacute Thyroiditis** (also known as De Quervain’s or Granulomatous Thyroiditis). **1. Why Subacute Thyroiditis is correct:** The diagnosis is confirmed by the FNAC findings of **epithelioid cells and multinucleated giant cells**, which represent the granulomatous inflammatory response to damaged thyroid follicles. This condition is typically triggered by a viral infection (e.g., Coxsackievirus, Mumps) and is the most common cause of a painful thyroid gland. [1] **2. Why the other options are incorrect:** * **Acute Thyroiditis:** Usually caused by a bacterial infection (e.g., *S. aureus*). While it presents with pain and fever, the cytology would show **neutrophils and abscess formation**, not granulomatous inflammation. * **Tubercular Lymphadenitis:** While it shows epithelioid granulomas and giant cells, it typically involves the **lateral cervical lymph nodes**, not a diffuse midline thyroid swelling. Primary tuberculosis of the thyroid is extremely rare. * **Hashimoto’s Thyroiditis:** This is a **painless** goiter. FNAC would reveal a dense lymphocytic infiltrate, germinal centers, and characteristic **Hürthle cells** (oncocytes), but not granulomas. [1] **3. NEET-PG High-Yield Pearls:** * **Etiology:** Post-viral; associated with **HLA-B35**. * **Clinical Phase:** Often follows a triphasic course: Hyperthyroidism (leakage of T3/T4) → Hypothyroidism → Recovery. [1] * **Lab Marker:** Characteristically high **ESR** with **low radioactive iodine uptake (RAIU)** due to follicular damage. [1] * **Treatment:** Self-limiting; managed with NSAIDs or corticosteroids for pain. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1089-1092.

Q: Which carcinoma does not arise from thyroid follicles?

Medullary carcinoma. The thyroid gland contains two distinct types of secretory cells with different embryological origins: **Follicular cells** and **Parafollicular (C) cells**. ### **Why Medullary Carcinoma is the Correct Answer** **Medullary Thyroid Carcinoma (MTC)** arises from the **Parafollicular C-cells**, which are derived from the **ultimobranchial body** (neural crest origin). These cells are responsible for secreting **Calcitonin**. Because MTC does not arise from follicular cells, it does not concentrate iodine and cannot be treated with Radioiodine (RAI) therapy. ### **Analysis of Incorrect Options** * **Papillary Carcinoma (B):** The most common thyroid malignancy; it arises directly from the thyroid follicular epithelium. * **Anaplastic Carcinoma (C):** An undifferentiated, highly aggressive tumor that arises from follicular cells, often via the dedifferentiation of a pre-existing well-differentiated carcinoma. * **Hürthle Cell Carcinoma (D):** A variant of follicular carcinoma characterized by oxyphilic cells (Askanazy cells). These are modified follicular cells packed with mitochondria. ### **NEET-PG High-Yield Pearls** * **Origin:** Follicular cells are endodermal; C-cells are neuroendocrine (neural crest). * **Tumor Markers:** * Papillary/Follicular: **Thyroglobulin**. * Medullary: **Calcitonin** (for diagnosis/follow-up) and **CEA** (for prognosis). * **Genetics:** MTC is associated with **RET proto-oncogene** mutations and occurs in **MEN 2A and 2B** syndromes. * **Amyloid Staining:** MTC is histologically characterized by **amyloid stroma** (stained with Congo Red), which represents pro-calcitonin deposits.

Question 1

Which thyroid carcinoma is associated with calcitonin amyloid deposition?

Accepted Answer

Medullary

Answer

Papillary

Answer

Follicular

Answer

Anaplastic

Question 2

Which of the following thyroid abnormalities is associated with IgG4-related disease?

Accepted Answer

Riedel thyroiditis

Answer

De Quervain thyroiditis

Answer

Postpartum thyroiditis

Answer

Hashimoto thyroiditis

Question 3

What is the most common site for a pheochromocytoma?

Accepted Answer

Adrenal medulla

Answer

Adrenal cortex

Answer

Paravertebral ganglion

Answer

Paraaortic-sympathetic chain

Question 4

A 5-year-old boy has developed features suggestive of precocious puberty over the past 6 months. On physical examination, the boy exhibits secondary sex characteristics, including pubic hair and penile enlargement. Which of the following morphologic features is most likely to be observed in his adrenal glands?

Accepted Answer

Cortical hyperplasia

Answer

Cortical atrophy

Answer

Cortical nodule

Answer

Medullary atrophy

Question 5

A 34-year-old patient presents with a thyroid nodule. Ultrasonography shows foci of calcification. Based on typical histological features, what is the likely diagnosis?

Accepted Answer

Papillary carcinoma

Answer

Follicular carcinoma

Answer

Medullary carcinoma

Answer

Anaplastic carcinoma

Question 6

A 20-year-old female patient presented with a thyroid swelling. Which of the following is least likely to be diagnosed by fine needle aspiration cytology?

Accepted Answer

Follicular carcinoma of thyroid

Answer

Non-Hodgkin's lymphoma of thyroid

Answer

Medullary carcinoma of thyroid

Answer

Papillary carcinoma of thyroid

Question 7

In Diabetes Mellitus type II, insulin resistance develops due to which of the following mechanisms?

Accepted Answer

End organ target receptor insensitivity

Answer

Diabetic ketoacidosis

Answer

Hyperosmolar non-ketotic state

Answer

Genetic predisposition

Question 8

A 40-year-old female presents with fever, fatigue, and diffuse painful swelling in the midline of the neck. Fine-needle aspiration cytology (FNAC) of the swelling reveals epithelioid cells and giant cells. What is the most likely diagnosis?

Accepted Answer

Subacute thyroiditis

Answer

Acute thyroiditis

Answer

Tubercular lymphadenitis

Answer

Hashimoto's thyroiditis

Question 9

Which carcinoma does not arise from thyroid follicles?

Accepted Answer

Medullary carcinoma

Answer

Papillary carcinoma

Answer

Anaplastic carcinoma

Answer

Hürthle cell carcinoma

Question 10

A boy presented with hypertension is found to have pheochromocytoma. All of the following are true about pheochromocytoma, EXCEPT:

Accepted Answer

Malignant tumor

Answer

Benign in nature

Answer

Secretes hormones

Answer

Hypertension is seen

Endocrine Pathology — MCQs

Endocrine Pathology — MCQs

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