Endocrine Pathology Practice Questions

Q: Multiple Endocrine Neoplasia (MEN) types II and III are associated with which gene mutation?

Ret. **Explanation:** The correct answer is **D. Ret**. **1. Why Ret is correct:** The **RET proto-oncogene**, located on chromosome **10q11.2**, encodes a receptor tyrosine kinase involved in cell growth and differentiation. Germline **gain-of-function mutations** in the RET gene are the hallmark of **MEN 2A (Type II)** and **MEN 2B (Type III)** [1]. * **MEN 2A:** Characterized by Medullary Thyroid Carcinoma (MTC), Pheochromocytoma, and Parathyroid hyperplasia [1]. * **MEN 2B:** Characterized by MTC, Pheochromocytoma, Mucosal neuromas, and Marfanoid habitus [1]. * *Note:* In contrast, MEN Type I is caused by a mutation in the *MEN1* gene (Menin protein) on chromosome 11. **2. Why other options are incorrect:** * **A. C-myc:** An oncogene (transcription factor) associated with **Burkitt Lymphoma** (t[8;14]). * **B. Erb-B2 (HER2/neu):** A growth factor receptor overexpressed in certain **Breast and Gastric cancers**. * **C. L-myc:** An oncogene primarily associated with **Small Cell Carcinoma of the Lung**. **High-Yield Clinical Pearls for NEET-PG:** * **Screening:** Prophylactic thyroidectomy is recommended for children carrying the RET mutation because Medullary Thyroid Carcinoma (MTC) occurs in nearly 100% of these patients. * **Hirschsprung Disease:** While *gain-of-function* RET mutations cause MEN 2, *loss-of-function* RET mutations are associated with Hirschsprung disease. * **MTC Marker:** Calcitonin is the tumor marker used for diagnosis and monitoring of MTC in MEN 2 patients. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1137.

Q: A 40-year-old male presented with a thyroid swelling and dysphagia. He gave history of on and off watery diarrhea. Biopsy of the lesion is shown. What is your diagnosis?

Medullary carcinoma of the thyroid. ***Medullary carcinoma of the thyroid*** - The combination of **thyroid swelling** with **watery diarrhea** strongly suggests medullary carcinoma, which arises from **C-cells** and secretes **calcitonin**. - Histologically shows **amyloid deposits in the stroma** and is associated with **MEN syndromes**, explaining the diarrheal symptoms due to excess calcitonin. *Follicular carcinoma of the thyroid* - Arises from **follicular epithelial cells** and typically presents as a **solitary thyroid nodule** without systemic symptoms like diarrhea. - Histologically shows **follicular architecture** with **capsular** or **vascular invasion**, lacking the amyloid deposits seen in medullary carcinoma. *Papillary carcinoma of the thyroid* - Most common thyroid malignancy arising from **follicular epithelial cells**, usually presenting as a painless thyroid mass without diarrhea. - Characterized by **papillary architecture**, **psammoma bodies**, and **Orphan Annie eye nuclei**, distinct from the neuroendocrine features of medullary carcinoma. *Anaplastic carcinoma of the thyroid* - Highly aggressive tumor presenting as a **rapidly enlarging thyroid mass** with severe **compressive symptoms** in elderly patients. - Histologically shows **undifferentiated cells** with **high mitotic activity** and **necrosis**, lacking the organized structure and amyloid deposits of medullary carcinoma.

Q: What is the ultrastructural finding in a case of paraganglioma?

Dense core granules. **Explanation:** **Paragangliomas** (and their adrenal counterpart, Pheochromocytoma) are neuroendocrine tumors derived from the extra-adrenal chromaffin cells of the autonomic nervous system. **Why "Dense core granules" is correct:** Under electron microscopy (ultrastructure), these cells characteristically contain numerous membrane-bound, electron-dense neurosecretory granules [1]. These are known as **"Zellballen"** granules or dense-core granules. They represent the storage sites for catecholamines (epinephrine and norepinephrine) and are a hallmark of neuroendocrine differentiation [1]. **Why the other options are incorrect:** * **A. Deposition of glycogen:** This is a characteristic feature of "Clear Cell" tumors, such as Clear Cell Renal Cell Carcinoma (RCC) or Ewing Sarcoma, but not neuroendocrine tumors. * **B & C. Enlarged/Shrunken mitochondria:** While mitochondrial abnormalities occur in various pathologies (e.g., Oncocytomas show an abundance of mitochondria), they are not the diagnostic ultrastructural feature for paragangliomas. **High-Yield Clinical Pearls for NEET-PG:** * **Histology:** Shows a characteristic **"Zellballen" pattern** (nests of cells surrounded by a delicate vascular stroma). * **Immunohistochemistry (IHC):** The chief cells are positive for **Chromogranin** and **Synaptophysin**, while the peripheral sustentacular cells are positive for **S-100**. * **Rule of 10s:** Historically associated with Pheochromocytoma (10% bilateral, 10% malignant, 10% extra-adrenal), though genetic understanding is evolving. * **Genetic Association:** Often linked to mutations in the **SDH (Succinate Dehydrogenase)** gene complex. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 484-485.

Question 1

Medullary thyroid carcinoma occurs due to the mutation of which oncogene or gene?

Accepted Answer

RET oncogene

Answer

P53 gene

Answer

RAS (H-RAS, K-RAS, N-RAS)

Answer

BRCA-1

Question 2

All of the following are features of De Quervain thyroiditis except?

Accepted Answer

Bacterial infection is a trigger in most patients.

Answer

In the early phase, follicles are disrupted and replaced by neutrophils forming microabscesses.

Answer

Inflammatory infiltrate is composed of lymphocytes, plasma cells, and macrophages with granuloma formation.

Answer

It is the most common cause of painful thyroid.

Question 3

Multiple Endocrine Neoplasia (MEN) types II and III are associated with which gene mutation?

Accepted Answer

Ret

Answer

C-myc

Answer

Erb-B2

Answer

L-myc

Question 4

A 40-year-old male presented with a thyroid swelling and dysphagia. He gave history of on and off watery diarrhea. Biopsy of the lesion is shown. What is your diagnosis?

Accepted Answer

Medullary carcinoma of the thyroid

Answer

Follicular carcinoma of the thyroid

Answer

Papillary carcinoma of the thyroid

Answer

Anaplastic carcinoma of the thyroid

Question 5

Which of the following is the most reliable feature of malignant transformation of pheochromocytoma?

Accepted Answer

None of the above

Answer

Presence of mitotic figures

Answer

Capsular invasion

Answer

Vascular invasion

Question 6

Which of the following is seen on electron microscopy of medullary thyroid carcinoma specimens?

Accepted Answer

Presence of electron-dense granules in the cytoplasm

Answer

Presence of electron-dense granules in the nucleus

Answer

Presence of electron-dense granules in the mitochondria

Answer

Presence of electron-dense granules in the endoplasmic reticulum

Question 7

What is the ultrastructural finding in a case of paraganglioma?

Accepted Answer

Dense core granules

Answer

Deposition of glycogen

Answer

Enlarged mitochondria

Answer

Shrunken mitochondria

Question 8

A 21-year-old woman experiences abruptio placentae with severe bleeding during the delivery of a term fetus. Five months later, she presents with profound lethargy, pallor, muscle weakness, failure of lactation, and amenorrhea. Which of the following pathologic findings is expected in this patient?

Accepted Answer

Infarction of the pituitary

Answer

Atrophy of the endocrine pancreas

Answer

Autoimmune destruction of the adrenal cortex

Answer

Pituitary prolactinoma

Question 9

All of the following are TRUE about Hashimoto's Thyroiditis, EXCEPT?

Accepted Answer

Orphan Annie eye nuclei

Answer

Follicular destruction

Answer

Increase in lymphocytes

Answer

Oncocytic metaplasia

Question 10

Spironolactone bodies are seen in which cellular structure?

Accepted Answer

None of the above

Answer

Neuron

Answer

Mitochondria

Answer

Hippocampus

Endocrine Pathology — MCQs

Endocrine Pathology — MCQs

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