Thyroid Cancer — MCQs
The following is a histopathological image of thyroid pathology. What is the diagnosis?
Which of the following conditions is the most common complication of radioiodine treatment for Graves' disease?
A 26-year-old male presents to the outpatient department with a discrete thyroid swelling. On neck ultrasound, an isolated cystic swelling of the gland is seen. What is the risk of malignancy associated with this finding?
Thyroid malignancies appear on USG as
Regarding anaplastic thyroid carcinoma, which of the following statements is true?
Which of the following is not a cause of oropharyngeal carcinoma?
Epithelioid hemangioendothelioma of the nose is classified as which of the following?
What is the commonest malignancy type in the oral cavity?
Recurrent or residual cancer of the nasopharynx after supervoltage radiotherapy is treated by which of the following?
A 13-year-old boy presents with cheek swelling and recurrent epistaxis. What is the most likely cause?
Thyroid Cancer Indian Medical PG Practice Questions and MCQs
Question 1: The following is a histopathological image of thyroid pathology. What is the diagnosis?
- A. Papillary carcinoma of thyroid
- B. Medullary carcinoma of thyroid (Correct Answer)
- C. Follicular carcinoma of thyroid
- D. Anaplastic carcinoma of thyroid
Explanation: ***Medullary carcinoma of thyroid*** - This image shows sheets and nests of **polygonal to spindle-shaped cells**, which are characteristic of medullary thyroid carcinoma, especially when mixed with an **amyloid stroma** (seen as amorphous eosinophilic material) [2]. - The presence of **neuroendocrine features** and the production of **calcitonin** are hallmarks of these C-cell tumors [1], [2]. *Papillary carcinoma of thyroid* - Characterized by **papillary architecture**, **ground-glass (Orphan Annie eye) nuclei**, nuclear grooves, and intranuclear cytoplasmic inclusions. - These features are not prominently seen in the provided image. *Follicular carcinoma of thyroid* - Defined by an invasive growth pattern of **well-differentiated follicular cells** forming follicles, with either capsular or vascular invasion [2]. - The image does not show classic follicular architectural patterns or clear evidence of invasion in the absence of a capsule. *Anaplastic carcinoma of thyroid* - This is a highly aggressive and undifferentiated tumor with **marked pleomorphism**, bizarre giant cells, and high mitotic activity [2]. - While there is some pleomorphism, the overall pattern and cellular morphology in the image are more consistent with medullary carcinoma than the extreme anaplasia. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1102-1103. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-431.
Question 2: Which of the following conditions is the most common complication of radioiodine treatment for Graves' disease?
- A. Hypothyroidism (Correct Answer)
- B. Thyroid cancer
- C. Thyroid storm
- D. Subacute thyroiditis
Explanation: ***Hypothyroidism*** - **Radioiodine (RAI) therapy** destroys overactive thyroid cells, making it highly effective for Graves' disease but often leading to a permanent state of **hypothyroidism** post-treatment. - The goal of RAI is to eliminate the source of excess hormone production, and while effective, it frequently necessitates lifelong **thyroid hormone replacement**. *Thyroid storm* - **Thyroid storm** is a rare, life-threatening complication, usually seen in untreated or undertreated hyperthyroidism or during acute stress, not typically a direct outcome of effective RAI. - While a transient increase in thyroid hormones can occur shortly after RAI, a full-blown thyroid storm is infrequent with proper preparation and management. *Thyroid cancer* - There is no significant evidence to suggest an increased risk of **thyroid cancer** in adults following therapeutic doses of radioiodine for Graves' disease [1]. - The radiation dose is targeted primarily at the thyroid gland, and studies have shown no clear link to increased malignancy [1]. *Subacute thyroiditis* - **Subacute thyroiditis** (also known as de Quervain's thyroiditis) is typically a post-viral inflammatory condition of the thyroid, characterized by pain and tenderness in the thyroid gland [2]. - It does not directly result from radioiodine treatment; however, some patients may experience a transient inflammatory response (radiation thyroiditis) after RAI, which is usually mild and self-limiting, not true subacute thyroiditis.
Question 3: A 26-year-old male presents to the outpatient department with a discrete thyroid swelling. On neck ultrasound, an isolated cystic swelling of the gland is seen. What is the risk of malignancy associated with this finding?
- A. 48%
- B. 12%
- C. 24%
- D. 3% (Correct Answer)
Explanation: ***3%*** - **Purely cystic thyroid nodules** (as described in this case with "isolated cystic swelling") have a **very low risk of malignancy**, typically **2-3%** or less. - According to **ATA guidelines** and **TIRADS classification**, purely cystic nodules are considered **low suspicion** lesions. - The cystic nature suggests a **benign process** such as a degenerated adenoma, colloid cyst, or simple cyst. - **Fine needle aspiration (FNA)** may still be considered if the nodule is >2 cm or has any suspicious solid components, but is often not required for purely cystic lesions. *48%* - This percentage is **significantly higher** than the actual malignancy risk for a purely cystic thyroid swelling. - Such a **high risk** would typically be associated with **solid nodules** exhibiting highly suspicious ultrasound features such as: - Microcalcifications - Irregular or spiculated margins - Taller-than-wide shape - Marked hypoechogenicity - Extrathyroidal extension *24%* - This percentage represents a **moderate to high risk** of malignancy, which is **not characteristic** of an isolated purely cystic thyroid swelling. - A risk in this range might be seen with: - **Mixed solid-cystic nodules** with predominantly solid components - Solid nodules with **intermediate suspicious features** on ultrasound *12%* - While lower than 24% or 48%, 12% is still **considerably higher** than the generally accepted malignancy risk for purely cystic thyroid nodules. - This risk level could be plausible for: - **Predominantly cystic nodules** with some eccentric solid components - Solid nodules with **mildly suspicious** features on ultrasound
Question 4: Thyroid malignancies appear on USG as
- A. Hyperechoic
- B. Isoechoic
- C. Hypoechoic (Correct Answer)
- D. Anechoic
Explanation: ***Hypoechoic*** - The majority of **malignant thyroid nodules** appear **hypoechoic** on ultrasound, meaning they reflect fewer sound waves than the surrounding tissues, making them appear darker. - This characteristic often correlates with increased cellularity and decreased colloid content within the tumor. *Hyperechoic* - **Hyperechoic** nodules are brighter than the surrounding parenchyma, which is more commonly associated with **benign conditions** like colloid cysts or hyperplastic nodules, although some rare malignancies can be hyperechoic. - This appearance suggests a higher density of reflections from, for example, colloid or calcifications. *Isoechoic* - **Isoechoic** nodules have similar echogenicity to the adjacent thyroid tissue, making them difficult to distinguish. - While some malignancies can be isoechoic, this feature is more often seen in **benign nodules** or early changes, making it a less specific indicator for malignancy. *Anechoic* - **Anechoic** lesions appear completely black on ultrasound, indicating no internal echoes, which is characteristic of **fluid-filled structures** like simple cysts. - Malignancies are typically solid or predominantly solid and therefore are rarely anechoic.
Question 5: Regarding anaplastic thyroid carcinoma, which of the following statements is true?
- A. Common in young
- B. Radiotherapy cures
- C. Associated with p53 mutation (Correct Answer)
- D. Surrounding neck tissue is usually free
Explanation: ***Associated with p53 mutation*** - **Anaplastic thyroid carcinoma** is a highly aggressive cancer frequently characterized by **p53 tumor suppressor gene mutations**. - These mutations contribute to its rapid growth, dedifferentiation, and resistance to therapy. *Common in young* - **Anaplastic thyroid carcinoma (ATC)** is a rare and highly aggressive malignancy that primarily affects **older adults**, typically those over 60 years of age. - It is one of the least differentiated forms of thyroid cancer and has a poor prognosis. [1] *Surrounding neck tissue is usually free* - ATC is characterized by **rapid growth** and **aggressive local invasion**, often involving surrounding neck tissues such as the trachea, esophagus, and great vessels. [1] - This extensive local involvement contributes to symptoms like dysphagia, dyspnea, and hoarseness, and makes surgical resection difficult or impossible. *Radiotherapy cures* - **ATC is largely refractory to conventional therapies**, including surgery, radiotherapy, and chemotherapy, due to its aggressive biology and common presence of dedifferentiated cells. - While radiation therapy may be used for **palliative management** of local symptoms, it very rarely achieves a cure; the prognosis remains extremely poor, with median survival measured in months. [1] **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1101-1102.
Question 6: Which of the following is not a cause of oropharyngeal carcinoma?
- A. Occupational exposure to hydrochloric acid (Correct Answer)
- B. Smoking
- C. Human Papilloma Virus infection
- D. Occupational exposure to isopropyl oil
Explanation: **Explanation:** The primary risk factors for oropharyngeal carcinoma (OPC) are lifestyle-related and viral, rather than chemical or industrial. **1. Why Option A is the Correct Answer:** Occupational exposure to **hydrochloric acid (HCl)** is primarily associated with dental erosion and irritation of the upper respiratory tract, but it is **not** a recognized carcinogen for the oropharynx. In contrast, exposure to strong inorganic acid mists (like sulfuric acid) is linked specifically to **laryngeal cancer**, not oropharyngeal cancer. **2. Analysis of Other Options:** * **Smoking (Option B):** Tobacco use is a classic risk factor. Carcinogens like nitrosamines and polycyclic aromatic hydrocarbons cause field cancerization, leading to squamous cell carcinoma (SCC) of the entire aerodigestive tract. * **Human Papilloma Virus (Option C):** HPV (specifically **Type 16**) is now the leading cause of oropharyngeal cancer globally, especially involving the palatine tonsils and base of tongue. HPV-positive tumors have a better prognosis than tobacco-related ones. * **Isopropyl Oil (Option D):** Occupational exposure to the manufacture of isopropyl alcohol (specifically the "strong acid process" involving isopropyl oil) is a documented risk factor for cancers of the **paranasal sinuses and the oropharynx**. **Clinical Pearls for NEET-PG:** * **Most Common Site:** The **palatine tonsil** is the most common site for oropharyngeal SCC. * **HPV Marker:** **p16** immunohistochemistry is used as a surrogate marker for HPV-associated oropharyngeal cancer. * **Plummer-Vinson Syndrome:** Associated with post-cricoid (hypopharyngeal) carcinoma, not primarily oropharyngeal. * **Diet:** Deficiencies in Vitamin A and C are also implicated in the development of oral and pharyngeal malignancies.
Question 7: Epithelioid hemangioendothelioma of the nose is classified as which of the following?
- A. Carcinoma
- B. Sarcoma (Correct Answer)
- C. Carcinosarcoma
- D. Hamartoma
Explanation: **Explanation:** **Epithelioid Hemangioendothelioma (EHE)** is a rare vascular neoplasm of intermediate malignancy. The correct classification is **Sarcoma** because it originates from mesenchymal tissue (specifically vascular endothelial cells). 1. **Why Sarcoma is Correct:** By definition, a sarcoma is a malignant tumor arising from mesenchymal cells (bone, cartilage, fat, muscle, or blood vessels). EHE is characterized by "epithelioid" endothelial cells that mimic epithelial cells in appearance but are positive for vascular markers like **CD31, CD34, and Factor VIII-related antigen**. It is considered an intermediate-grade vascular sarcoma, falling between a benign hemangioma and a highly aggressive angiosarcoma. 2. **Why Other Options are Incorrect:** * **Carcinoma:** These are malignant tumors of **epithelial** origin (e.g., Squamous Cell Carcinoma). While EHE has "epithelioid" features histologically, its lineage is endothelial (mesenchymal). * **Carcinosarcoma:** This is a true "mixed" tumor containing both malignant epithelial and malignant mesenchymal components. * **Hamartoma:** This is a benign, disorganized growth of mature native tissue. EHE is a neoplastic process with metastatic potential, not a developmental malformation. **High-Yield Clinical Pearls for NEET-PG:** * **Histology:** Look for "intracytoplasmic vacuoles" (lumina) containing red blood cells within epithelioid cells. * **Genetics:** Often associated with a specific translocation: **t(1;3)(p36;q25)** resulting in the **WWTR1-CAMTA1** fusion gene. * **Behavior:** It is locally invasive and has a metastatic rate of approximately 20-30%. * **Treatment:** Wide surgical excision is the primary modality; it is generally resistant to radiotherapy and chemotherapy.
Question 8: What is the commonest malignancy type in the oral cavity?
- A. Adenocarcinoma
- B. Transitional cell carcinoma
- C. Squamous cell carcinoma (Correct Answer)
- D. Basal cell carcinoma
Explanation: **Explanation:** **Correct Answer: C. Squamous cell carcinoma (SCC)** The oral cavity is lined by **stratified squamous epithelium**. Malignant transformation of these cells leads to Squamous Cell Carcinoma, which accounts for over **90-95%** of all oral cavity cancers. The primary risk factors include tobacco (smoking and smokeless), betel nut chewing, and chronic alcohol consumption. The most common site within the oral cavity for SCC is the **lower lip** (globally) or the **buccal mucosa/retro-molar trigone** (in the Indian subcontinent due to tobacco chewing habits). **Why other options are incorrect:** * **A. Adenocarcinoma:** These arise from glandular tissue. In the oral cavity, they originate from minor salivary glands. While they are the second most common group, they are far less frequent than SCC. * **B. Transitional cell carcinoma:** This type of epithelium is characteristic of the urinary tract (urothelium). It is not found in the oral cavity. * **D. Basal cell carcinoma (BCC):** BCC is a skin cancer (rodent ulcer) arising from the basal layer of the epidermis. While it commonly occurs on the face (above the line joining the tragus to the angle of the mouth), it does not arise from the oral mucosa. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site (India):** Buccal mucosa (often referred to as the "Indian Oral Cancer"). * **Most common site (Global):** Lower lip. * **Premalignant conditions:** Leukoplakia (most common), Erythroplakia (highest risk of transformation), and Oral Submucous Fibrosis (OSMF). * **Lymphatic spread:** Usually to Level I, II, and III neck nodes. * **Staging:** The "Worst Pattern of Invasion" (WPOI) and "Depth of Invasion" (DOI) are critical prognostic factors in the latest AJCC staging.
Question 9: Recurrent or residual cancer of the nasopharynx after supervoltage radiotherapy is treated by which of the following?
- A. Intracavitary radioactive implants
- B. Cryotherapy
- C. Surgery
- D. All of the above (Correct Answer)
Explanation: **Explanation:** The primary treatment for Nasopharyngeal Carcinoma (NPC) is **Radiotherapy (RT)** because the tumor is highly radiosensitive and the anatomical location makes primary surgical access difficult. However, managing **recurrent or residual disease** after full-course supervoltage radiotherapy is challenging because the area has already received its maximum tolerance dose of radiation. **Why "All of the above" is correct:** When external beam radiation fails, a multi-modal salvage approach is required: 1. **Intracavitary Radioactive Implants (Brachytherapy):** This allows for a high dose of radiation to be delivered directly to the tumor site while sparing the surrounding healthy tissues that were previously irradiated. Gold grains or Iridium-192 are commonly used. 2. **Surgery (Nasopharyngectomy):** While technically demanding, salvage surgery (via maxillary swing or endoscopic approaches) is indicated for localized resectable recurrences. 3. **Cryotherapy:** This is a palliative or adjunct option used to destroy localized residual tumor cells using extreme cold, especially in patients who are not candidates for major surgery. **Clinical Pearls for NEET-PG:** * **Primary Treatment of Choice:** Radiotherapy (specifically IMRT) is the gold standard for NPC. * **EBV Association:** NPC (especially Type 2 and 3) is strongly associated with the **Epstein-Barr Virus**. Monitoring EBV DNA levels is useful for detecting recurrence. * **Fossa of Rosenmüller:** This is the most common site of origin for NPC. * **Trotter’s Triad:** A classic presentation of NPC involving: 1. Conductive deafness (Eustachian tube blockage) 2. Ipsilateral temporoparietal neuralgia (CN V involvement) 3. Palatal paralysis (CN X involvement)
Question 10: A 13-year-old boy presents with cheek swelling and recurrent epistaxis. What is the most likely cause?
- A. Angiofibroma (Correct Answer)
- B. Carcinoma of the nasopharynx
- C. Rhabdomyosarcoma
- D. None of the above
Explanation: **Explanation:** The clinical presentation of a **13-year-old boy** with **recurrent epistaxis** and **cheek swelling** is a classic "spotter" for **Juvenile Nasopharyngeal Angiofibroma (JNA)**. **1. Why Angiofibroma is correct:** JNA is a benign but locally aggressive, highly vascular tumor that occurs almost exclusively in **adolescent males** (testosterone-dependent). * **Epistaxis:** The most common symptom is profuse, painless, recurrent epistaxis due to the tumor's extreme vascularity. * **Cheek Swelling:** As the tumor grows, it typically expands from the sphenopalatine foramen into the **pterygopalatine fossa** and then laterally into the **infratemporal fossa**, leading to the characteristic "frog-face" deformity or cheek swelling. **2. Why other options are incorrect:** * **Carcinoma of the nasopharynx:** While it can cause epistaxis and nasal obstruction, it is rare in young children and more commonly presents with cervical lymphadenopathy and serous otitis media. * **Rhabdomyosarcoma:** This is the most common soft tissue sarcoma in children. While it can occur in the head and neck, it usually presents as a rapidly enlarging, painful mass rather than the classic pattern of recurrent, profuse epistaxis seen in JNA. **3. High-Yield Clinical Pearls for NEET-PG:** * **Origin:** Sphenopalatine foramen (near the posterior end of the middle turbinate). * **Holman-Miller Sign (Antral Sign):** Anterior bowing of the posterior wall of the maxillary sinus seen on CT/MRI. * **Diagnosis:** Contrast-enhanced CT (CECT) is the investigation of choice. **Biopsy is strictly contraindicated** due to the risk of torrential hemorrhage. * **Treatment:** Surgical excision (Pre-operative embolization is often done to reduce blood loss).
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