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?
Trismus in carcinoma of the temporal bone occurs due to involvement of:
Epithelioid hemangioendothelioma of the nose is classified as which of the following?
What is the commonest malignancy type in the oral cavity?
In which TNM staging of glottis carcinoma is cancer limited to the larynx with vocal cord fixation?
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: Trismus in carcinoma of the temporal bone occurs due to involvement of:
- A. Dura
- B. Temporomandibular joint (Correct Answer)
- C. Mastoid
- D. Eustachian tube
Explanation: **Explanation:** In the context of temporal bone carcinoma (most commonly Squamous Cell Carcinoma), **Trismus** (inability to open the mouth) is a significant clinical sign indicating **anterior extension** of the tumor. **Why the Temporomandibular Joint (TMJ) is correct:** The anterior wall of the external auditory canal (EAC) is in direct anatomical proximity to the glenoid fossa and the TMJ. When a malignancy breaches the anterior bony or cartilaginous wall of the EAC, it invades the TMJ and the associated pterygoid muscles. This infiltration leads to pain and mechanical restriction of mandibular movement, resulting in trismus. This finding usually signifies an advanced stage (T3 or T4) and a poorer prognosis. **Why other options are incorrect:** * **Dura:** Involvement of the dura (superior extension through the tegmen) leads to neurological complications, CSF otorrhea, or meningitis, but does not mechanically restrict jaw movement. * **Mastoid:** Posterior extension into the mastoid air cells causes retroauricular pain and swelling, but the mastoid process does not interface with the muscles of mastication. * **Eustachian tube:** While the tumor can involve the Eustachian tube leading to middle ear effusion and conductive hearing loss, it does not cause the muscular or joint fixation required for trismus. **High-Yield NEET-PG Pearls:** * **Most common site:** The External Auditory Canal is the most common site for temporal bone malignancy. * **Most common histology:** Squamous Cell Carcinoma. * **Clinical Red Flag:** Chronic otorrhea that becomes **blood-stained** or is associated with **deep-seated ear pain** should always be suspicious of malignancy. * **Staging:** Facial nerve palsy and Trismus are indicators of advanced disease (T4 in the modified Pittsburgh staging system).
Question 8: 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 9: 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 10: In which TNM staging of glottis carcinoma is cancer limited to the larynx with vocal cord fixation?
- A. T1
- B. T2
- C. T3 (Correct Answer)
- D. T4
Explanation: **Explanation:** The staging of Glottic Carcinoma is primarily determined by vocal cord mobility and the extent of local spread. * **T3 (Correct Answer):** By definition, T3 glottic cancer is characterized by a tumor limited to the larynx with **vocal cord fixation**. This fixation usually occurs due to invasion of the thyroarytenoid muscle, cricoarytenoid joint, or involvement of the recurrent laryngeal nerve. It may also involve the paraglottic space or show minor thyroid cartilage erosion (inner cortex). **Analysis of Incorrect Options:** * **T1:** The tumor is limited to the vocal cord(s) with **normal mobility**. T1a involves one cord; T1b involves both. * **T2:** The tumor extends to the supraglottis or subglottis, but the vocal cords maintain **impaired mobility** (paretic) rather than complete fixation. * **T4:** This represents advanced disease where the tumor invades **beyond the larynx**. T4a involves the thyroid cartilage (outer cortex), trachea, or soft tissues of the neck; T4b involves the prevertebral space or encases the carotid artery. **High-Yield Clinical Pearls for NEET-PG:** 1. **Most Common Site:** The glottis is the most common site for laryngeal cancer. 2. **Prognosis:** Glottic cancers have the best prognosis because they present early (hoarseness) and the vocal cords have sparse lymphatic drainage, leading to low rates of nodal metastasis. 3. **Management:** T1 and T2 are typically managed with radiotherapy or laser excision (organ preservation), while T3 often requires concurrent chemoradiotherapy or total laryngectomy if the airway is compromised.
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