Thyroid Nodules and Cancer — MCQs
Metastases from follicular carcinoma should be treated by:
Which type of thyroid cancer is associated with primary hyperparathyroidism and phaeochromocytoma?
Which of the following conditions is the most common complication of radioiodine treatment for Graves' disease?
Radiation exposure can lead to which type of thyroid carcinoma?
A 45-year-old female presents with a 2 cm thyroid nodule. Which TIRADS category has >95% risk of malignancy?
Thyroid nodule in a 65 year old male who is clinically euthyroid is most likely to be
Treatment of choice for recurrent thyrotoxicosis after surgery is:-
A case of solitary thyroid nodule; the investigation of choice is:
What is the most common carcinoma of the thyroid?
Mark the false statement regarding Hürthle cell carcinoma:
Thyroid Nodules and Cancer Indian Medical PG Practice Questions and MCQs
Question 1: Metastases from follicular carcinoma should be treated by:
- A. Radioiodine (Correct Answer)
- B. Surgery
- C. Thyroxine
- D. Observation
Explanation: ***Radioiodine*** - **Differentiated thyroid cancers**, including **follicular carcinoma**, retain the ability to uptake iodine, making **radioiodine (I-131) therapy** highly effective for treating metastases [1]. - This therapy targets and destroys thyroid cancer cells wherever they are located in the body, including distant metastatic sites. *Surgery* - While surgery (e.g., **thyroidectomy**) is the primary treatment for localized thyroid cancer and can be used to resect some metastases, it is **not always feasible** for all metastatic sites, especially widely disseminated disease. - Surgery for widespread metastases carries significant risks and may not be curative if all tumor burden cannot be removed. *Thyroxine* - **Thyroxine (T4)** replacement therapy is crucial after thyroidectomy to replace missing hormones and to **suppress TSH** production, which can stimulate residual cancer growth [1]. - However, thyroxine itself does **not directly destroy** existing metastases; it's a supportive and suppressive therapy, not a primary treatment for metastases. *Observation* - **Observation** is generally not appropriate for treating metastases from **follicular carcinoma**, as these metastases have the potential to grow and lead to significant morbidity and mortality if left untreated. - Active treatment is usually indicated to improve prognosis and quality of life.
Question 2: Which type of thyroid cancer is associated with primary hyperparathyroidism and phaeochromocytoma?
- A. Medullary carcinoma of the thyroid (Correct Answer)
- B. Papillary carcinoma of the thyroid
- C. Anaplastic carcinoma of the thyroid
- D. Follicular carcinoma of the thyroid
Explanation: ***Medullary carcinoma of the thyroid*** - Associated with **multiple endocrine neoplasia (MEN) syndrome type 2**, which includes primary hyperparathyroidism and phaeochromocytoma [1]. - Medullary carcinoma arises from **C cells** (parafollicular cells) and is linked with **elevated calcitonin** levels. *Papillary carcinoma of the thyroid* - The most common type of thyroid cancer, but **not associated** with MEN syndromes. - Typically presents as a solitary **nodule** and is linked with **radiation exposure** rather than endocrine syndromes. *Anaplastic carcinoma of the thyroid* - A highly aggressive and undifferentiated form of thyroid cancer, often associated with **poor prognosis**. - Usually arises in older adults and does not have associations with **hyperparathyroidism** or phaeochromocytoma. *Follicular carcinoma of the thyroid* - Characterized by **thyroid follicle formation** and can be associated with **iodine deficiency**, but not with MEN syndromes. - It usually presents as a **solitary thyroid nodule** and lacks connection with **primary hyperparathyroidism**.
Question 3: 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 4: Radiation exposure can lead to which type of thyroid carcinoma?
- A. Lymphoma
- B. Papillary carcinoma (Correct Answer)
- C. Medullary carcinoma
- D. Follicular carcinoma
Explanation: ***Papillary carcinoma*** - Papillary thyroid carcinoma is strongly associated with **radiation exposure**, particularly during childhood [1]. - It is the most prevalent type of thyroid cancer and typically has a **good prognosis** [1]. *Lymphoma* - Thyroid lymphoma is rare and generally not linked to **radiation exposure**; it often presents as a **rapidly enlarging goiter**. - It is more commonly associated with **autoimmune thyroiditis**, not primary radiation effects. *Follicular carcinoma* - Follicular carcinoma shows a correlation with **iodine deficiency** rather than radiation exposure [1]. - Its presentation is more subtle, compared to the classical association of **radiation with papillary carcinoma**. *Medullary carcinoma* - Medullary thyroid carcinoma is primarily linked to **familial syndromes** like MEN 2 and not radiation exposure. - It arises from **parafollicular C cells**, making it clinically distinct from radiation-related types. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1098-1099.
Question 5: A 45-year-old female presents with a 2 cm thyroid nodule. Which TIRADS category has >95% risk of malignancy?
- A. TIRADS 4
- B. TIRADS 2
- C. TIRADS 5 (Correct Answer)
- D. TIRADS 3
Explanation: ***TIRADS 5*** - A **TIRADS 5** classification indicates a **highly suspicious** nodule with features strongly suggestive of **malignancy**. - This category corresponds to a **>95% risk of malignancy**, necessitating further investigation such as fine-needle aspiration (FNA). *TIRADS 4* - **TIRADS 4** nodules are classified as **moderately suspicious** for malignancy, with a risk ranging from **5% to 50%**. - While requiring follow-up and often FNA, the risk is significantly lower than for TIRADS 5. *TIRADS 2* - **TIRADS 2** nodules are considered **benign**, with a **0% risk of malignancy** (or extremely low). - These nodules typically have features like **spongiform appearance** or purely cystic composition. *TIRADS 3* - **TIRADS 3** nodules are classified as **mildly suspicious**, with a malignancy risk between **0% and 5%**. - They often have some indeterminate features but are predominantly considered to be low risk.
Question 6: Thyroid nodule in a 65 year old male who is clinically euthyroid is most likely to be
- A. Follicular adenoma (Correct Answer)
- B. Multinodular goiter
- C. Thyroid cyst
- D. Follicular carcinoma
Explanation: ***Follicular adenoma*** - Typically presents as a **solitary, well-defined nodule** in euthyroid patients, making it a common finding in this demographic. - It is often **benign** and can be differentiated from malignancies through imaging and cytological evaluation. *Multinodular goiter* - Usually involves multiple nodules rather than a **single nodule**, and patients often present with thyroid dysfunction [1]. - More common in women, and does not fit the profile of a solitary nodule in a euthyroid male. *Follicular Carcinoma* - While it can present as a nodule, it typically involves **elevated risk factors** such as family history and certain genetic mutations. - Euthyroid status alone is insufficient for a diagnosis of malignancy without further alarming features. *Thyroid Cyst* - Cysts are usually **fluid-filled** and may not present as solid nodules, which are common in cases described. - They tend to be **asymptomatic** and are generally **benign**, lacking the solid characteristics of a follicular adenoma.
Question 7: Treatment of choice for recurrent thyrotoxicosis after surgery is:-
- A. Observation & follow-up
- B. Radioiodine (Correct Answer)
- C. Radioiodine followed by surgery
- D. Further surgery
Explanation: ***Radioiodine*** - **Radioiodine therapy (RAI)** is the preferred treatment for recurrent **thyrotoxicosis** after prior surgery, especially if the patient is elderly or has comorbidities, due to its effectiveness and safety profile. [1] - It works by destroying overactive thyroid cells, reducing hormone production and mitigating the risk of further surgical complications. *Observation & follow-up* - This approach is generally **insufficient** for managing recurrent thyrotoxicosis, which requires active treatment to control hormone levels. - Delaying proper treatment can lead to serious complications such as **cardiac arrhythmias**, **osteoporosis**, and **thyroid storm**. *Radioiodine followed by surgery* - Administering radioiodine followed by surgery is **not typically a standard approach** for recurrent thyrotoxicosis and may increase patient burden and risk. - Surgery after radioiodine therapy is usually reserved for cases of **malignancy** or large goiters with compressive symptoms that persist despite RAI. [1] *Further surgery* - **Repeat thyroid surgery** carries a significantly **higher risk of complications** such as recurrent laryngeal nerve injury, hypoparathyroidism, and excessive bleeding due to altered anatomy and scar tissue from the initial surgery. [1] - The efficacy may also be reduced compared to RAI, particularly in diffuse or widespread recurrence.
Question 8: A case of solitary thyroid nodule; the investigation of choice is:
- A. T3, T4 estimation
- B. Thyroid scan
- C. FNAC (Correct Answer)
- D. Excision biopsy
Explanation: ***Correct: FNAC*** - **Fine needle aspiration cytology (FNAC)** is the most important and definitive diagnostic tool for evaluating the malignancy risk of a **solitary thyroid nodule**. - It's a minimally invasive, cost-effective procedure with high sensitivity and specificity in differentiating **benign** from **malignant** lesions. - FNAC is recommended as the **first-line investigation** by major thyroid guidelines (ATA, BTA). *Incorrect: T3, T4 estimation* - **Thyroid hormone levels (T3, T4)** primarily assess thyroid function (hyperthyroidism or hypothyroidism), not the **malignancy potential** of a nodule itself. - While thyroid dysfunction can sometimes be associated with nodules, these tests alone cannot definitively diagnose or rule out cancer. - Thyroid function tests are complementary but not the primary investigation for nodule characterization. *Incorrect: Thyroid scan* - A **thyroid scan** (using radioactive iodine) helps determine if a nodule is "hot" (hyperfunctioning/benign) or "cold" (non-functioning/potentially malignant). - However, it cannot definitively differentiate between benign and malignant **cold nodules**, which require further investigation, typically FNAC. - Thyroid scanning has largely been superseded by ultrasound and FNAC in modern practice. *Incorrect: Excision biopsy* - **Excision biopsy** (surgical removal) is a treatment for a thyroid nodule rather than the initial investigation of choice. - It is typically performed when **FNAC results are indeterminate** or suspicious for malignancy, or when the nodule is significantly large or symptomatic. - This is an invasive procedure with surgical risks and is not appropriate as a first-line investigation.
Question 9: What is the most common carcinoma of the thyroid?
- A. Papillary thyroid carcinoma (Correct Answer)
- B. Follicular thyroid carcinoma
- C. Hurthle cell carcinoma
- D. Medullary thyroid carcinoma
Explanation: ***Papillary thyroid carcinoma*** - This is the **most common type** of thyroid cancer, accounting for approximately 80-85% of all thyroid malignancies [1], [2]. - It typically has an **excellent prognosis** due to its relatively slow growth and tendency to metastasize through lymphatics rather than hematogenously [2]. *Follicular thyroid carcinoma* - This is the **second most common** type of thyroid cancer, comprising about 10-15% of cases [2]. - It tends to metastasize **hematogenously** to distant sites like bones and lungs, which is a key differentiator from papillary carcinoma [2]. *Hurthle cell carcinoma* - Also known as **oxyphilic follicular carcinoma**, this is considered a variant of follicular carcinoma, though sometimes classified separately. - It is **less common** than papillary or follicular carcinoma and is characterized by cells with abundant, eosinophilic, granular cytoplasm. *Medullary thyroid carcinoma* - This is a neuroendocrine tumor arising from the **parafollicular C cells** of the thyroid, which produce **calcitonin** [3], [4]. - It accounts for only about 3-5% of thyroid cancers and can be sporadic or hereditary, often associated with **MEN 2 syndromes** [3], [4]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1098-1099. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-430. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-429. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1102-1103.
Question 10: Mark the false statement regarding Hürthle cell carcinoma:
- A. It can be diagnosed by FNAC. (Correct Answer)
- B. Arises from Hürthle cells of the thyroid.
- C. Central neck dissection is performed in certain cases.
- D. It is not a variant of papillary thyroid cancer.
Explanation: ***It can be diagnosed by FNAC.*** - **Fine-needle aspiration cytology (FNAC)** alone cannot definitively diagnose Hürthle cell carcinoma because distinguishing between **benign Hürthle cell adenoma** and **malignant Hürthle cell carcinoma** requires evidence of **capsular or vascular invasion**, which cannot be assessed cytologically [1]. - FNAC results typically return as "**follicular neoplasm, Hürthle cell type**" or "**suspicious for Hürthle cell neoplasm**," necessitating surgical excision for definitive diagnosis [1]. *Arises from Hürthle cells of the thyroid.* - This statement is **true** because Hürthle cell carcinoma originates from **Hürthle cells** (also known as oxyphil cells or oncocytes), which are found in the thyroid gland. - These cells are characterized by abundant **eosinophilic, granular cytoplasm** due to a high concentration of mitochondria. *Central neck dissection is performed in certain cases.* - This statement is **true** because **central neck dissection** is considered in Hürthle cell carcinoma when there is evidence of **lymph node metastasis** or **high-risk disease features**. - While Hürthle cell carcinoma is less likely to metastasize to lymph nodes than papillary thyroid carcinoma, such an intervention may be necessary for staging and disease control. *It is not a variant of papillary thyroid cancer.* - This statement is **true** because Hürthle cell carcinoma is a distinct entity, classified as a variant of **follicular thyroid carcinoma**, not papillary thyroid carcinoma [1]. - It has a separate biological behavior and treatment strategy compared to papillary thyroid cancer. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1100-1101.
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