Endocrine Pathology Practice Questions

Q: RET gene mutation is associated with which malignancy?

Medullary carcinoma thyroid. **Explanation:** The **RET (REarranged during Transformation)** gene is a proto-oncogene located on chromosome 10q11.2 that encodes a receptor tyrosine kinase [1]. Mutations in this gene lead to constitutive activation of signaling pathways, primarily affecting cells derived from the **neural crest**. **1. Why Medullary Carcinoma Thyroid (MCT) is correct:** MCT arises from the **Parafollicular C-cells** of the thyroid, which are neuroendocrine cells derived from the neural crest. Germline mutations in the RET proto-oncogene are the hallmark of **Multiple Endocrine Neoplasia (MEN) type 2A and 2B**, where MCT is the most consistent feature (occurring in nearly 100% of cases) [1, 2]. It is also seen in Familial Medullary Thyroid Carcinoma (FMTC) [1]. **2. Analysis of Incorrect Options:** * **Pheochromocytoma:** While RET mutations *are* associated with Pheochromocytoma (as part of MEN 2A/2B), MCT is the most characteristic malignancy directly linked to RET [2]. However, in the context of a single best answer for "RET gene mutation," MCT is the primary association taught in pathology and surgery. * **Lymphoma:** Associated with mutations in genes like BCL-2, BCL-6, or MYC, but not RET. * **Renal Cell Carcinoma:** Most commonly associated with the **VHL gene** (Von Hippel-Lindau) on chromosome 3. **3. NEET-PG High-Yield Pearls:** * **Hirschsprung Disease:** Loss-of-function mutations in the RET gene are associated with this congenital condition (failure of neural crest cell migration) [1]. * **MEN 2A:** MCT + Pheochromocytoma + Parathyroid Hyperplasia [1]. * **MEN 2B:** MCT + Pheochromocytoma + Mucosal Neuromas + Marfanoid habitus [2]. * **Prophylactic Thyroidectomy:** Recommended for children carrying RET mutations to prevent the inevitable development of MCT.

Q: All of the following statements are true regarding craniopharyngioma, except:

Aggressive malignant tumor. **Explanation:** Craniopharyngiomas are **WHO Grade 1 (benign)**, slow-growing epithelial tumors. While they can be locally invasive and have a high recurrence rate due to their proximity to vital structures (optic chiasm, hypothalamus), they are **not aggressive malignant tumors**. This makes Option B the correct "except" choice. **Analysis of Options:** * **Option A:** These tumors originate from the remnants of **Rathke’s pouch** (an ectodermal outpocketing of the oropharynx). * **Option C:** The **Papillary variant** is seen primarily in adults. It is characterized by solid sheets of squamous epithelium and is strongly associated with the **BRAF V600E mutation**. * **Option D:** The **Adamantinomatous variant** is more common in children. It is characterized by "wet keratin" (stellate reticulum) and calcification. It is driven by mutations in the **CTNNB1 gene**, leading to the activation of the **WNT/beta-catenin pathway**. **High-Yield Clinical Pearls for NEET-PG:** * **Bimodal Age Distribution:** Peaks at 5–15 years and >45 years. * **Imaging:** Classic "machinery oil" appearance (dark, cholesterol-rich fluid) within cysts, especially in the adamantinomatous type. * **Clinical Presentation:** Visual field defects (Bitemporal hemianopia) and endocrine dysfunction (Diabetes Insipidus, growth retardation) [1]. * **Calcification:** A hallmark feature on CT scans (present in >90% of pediatric cases). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1084-1085.

Q: Follicular carcinoma of the thyroid is mostly due to a mutation of which gene?

NRAS. **Explanation:** Follicular Carcinoma of the Thyroid (FTC) is characterized by specific genetic alterations that drive follicular cell proliferation [1]. The most common mutations involve the **RAS oncogene family**, specifically point mutations in **NRAS**. 1. **Why NRAS is correct:** Mutations in the RAS family (NRAS, HRAS, and KRAS) are found in approximately 40-50% of Follicular Carcinomas [1]. Among these, **NRAS** is the most frequently mutated isoform. These mutations activate the MAPK and PI3K/AKT signaling pathways, promoting uncontrolled cellular growth [1]. Another significant genetic hallmark of FTC is the **PAX8-PPARG** fusion gene (t(2;3)(q13;p25)), seen in about 30-35% of cases. 2. **Why other options are incorrect:** * **HRAS & KRAS:** While these are part of the RAS family and can be mutated in FTC, they occur much less frequently than NRAS. * **NTRK1:** Rearrangements involving *NTRK1* are typically associated with **Papillary Thyroid Carcinoma (PTC)**, not Follicular Carcinoma [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Follicular Carcinoma:** Spreads primarily via **hematogenous route** (to lungs and bone). Lymphatic spread is rare (unlike PTC). * **Diagnosis:** Cannot be made by FNAC. Histological evidence of **capsular or vascular invasion** is mandatory to distinguish FTC from Follicular Adenoma [2]. * **Iodine Deficiency:** FTC is more common in areas with dietary iodine deficiency [1]. * **Hürthle Cell Carcinoma:** A variant of FTC characterized by abundant granular eosinophilic cytoplasm (due to mitochondria) [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1097-1098. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1096-1097.

Question 1

RET gene mutation is associated with which malignancy?

Accepted Answer

Medullary carcinoma thyroid

Answer

Pheochromocytoma

Answer

Lymphoma

Answer

Renal cell carcinoma

Question 2

Pheochromocytomas are known to arise from all of the following locations, except:

Accepted Answer

Chest wall

Answer

Adrenal gland

Answer

Mediastinum

Answer

Neck

Question 3

All of the following are seen in follicular carcinoma of the thyroid, except?

Accepted Answer

Point mutations of TP53

Answer

PAX8-PPARG fusion

Answer

RAS gene mutations

Answer

Loss-of-function mutations of PTEN gene

Question 4

A female neonate with DiGeorge syndrome develops severe muscle cramps and convulsions soon after birth. Which of the following is the cause of convulsions in this neonate?

Accepted Answer

Hypocalcemia

Answer

Acute hemorrhagic adrenalitis

Answer

Hypoglycemia

Answer

Hypokalemia

Question 5

Hürthle cell carcinoma is a variant of which thyroid carcinoma?

Accepted Answer

Follicular carcinoma

Answer

Medullary carcinoma

Answer

Papillary carcinoma

Answer

Anaplastic carcinoma

Question 6

All of the following statements are true regarding craniopharyngioma, except:

Accepted Answer

Aggressive malignant tumor

Answer

Origin from Rathke's pouch

Answer

Papillary variant of the tumor is associated with BRAF V600E mutation

Answer

Adamantinomatous variant is associated with abnormality in WNT/CTNNB1 (beta-catenin) pathway

Question 7

Follicular carcinoma of the thyroid is mostly due to a mutation of which gene?

Accepted Answer

NRAS

Answer

HRAS

Answer

KRAS

Answer

NTRK1

Question 8

What is the most common functional neuroendocrine tumor of the pancreas associated with Multiple Endocrine Neoplasia type 1 (MEN1)?

Accepted Answer

Gastrinoma

Answer

Glucagonoma

Answer

VIPoma

Answer

Somatostatinoma

Question 9

Zellballen pattern is found in the histology of which of the following conditions?

Accepted Answer

Paraganglioma

Answer

Neuroblastoma

Answer

Ewing's Sarcoma

Answer

Renal Cell Carcinoma (RCC)

Question 10

A patient undergoes total thyroidectomy for a mass lesion of the thyroid. During the surgery, the surgeon notes that the parathyroid glands appeared enlarged. The thyroid lesion shows neuroendocrine-type cells and amyloid deposition. This patient's thyroid and parathyroid lesions may be related to which of the following oncogenes?

Accepted Answer

ret

Answer

bcl-2

Answer

C-myc

Answer

erb-B2

Endocrine Pathology — MCQs

Endocrine Pathology — MCQs

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