Thyroid Cancer — MCQs
What is the most common thyroid tumor associated with multiple endocrine neoplasia (MEN)?
A female presents with a 1 × 1 cm thyroid swelling. What is the next best step in management?
All of the following are histological features of Hashimoto thyroiditis, except which of the following?
A patient presents with neck swelling causing compression of the trachea and esophagus. Histopathological assessment reveals cell nests and pink extracellular amyloid stroma. What is the cell of origin of the tumor associated with these findings?
What is the most appropriate initial investigation for a solitary thyroid nodule (STN)?
What is the treatment of choice for medullary carcinoma of the thyroid?
Treatment of resectable T4N0M0 stage of head and neck carcinoma is?
Which of the following factors is not included in the MACIS score used for the prognosis of papillary thyroid cancer?
Most common nerve injured in ligation of inferior thyroid artery
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 Cancer Indian Medical PG Practice Questions and MCQs
Question 1: What is the most common thyroid tumor associated with multiple endocrine neoplasia (MEN)?
- A. Follicular
- B. Papillary
- C. Anaplastic
- D. Medullary (Correct Answer)
Explanation: ***Medullary*** - The **commonest thyroid tumor** in Multiple Endocrine Neoplasia (MEN) type 2 is medullary thyroid carcinoma, associated with **calcitonin production** [1]. - It arises from **C cells (parafollicular cells)** and is linked to **RET oncogene mutations** in MEN syndromes [1]. *Papillary* - Papillary thyroid carcinoma is the **most common thyroid cancer overall**, but not specifically associated with MEN syndromes. - It typically presents with **lymphatic spread**, whereas medullary carcinoma has a different genetic association. *Follicular* - Follicular thyroid carcinoma is less common in MEN and usually occurs sporadically. - It primarily arises from **follicular cells** and involves a different mechanism than medullary carcinoma. *Anaplastic* - Anaplastic thyroid carcinoma is a rare and highly aggressive form, not commonly associated with MEN. - It usually arises from **differentiated thyroid cancers** and presents in older patients, which does not align with MEN's typical presentations. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1102-1103.
Question 2: A female presents with a 1 × 1 cm thyroid swelling. What is the next best step in management?
- A. I-131
- B. TSH (Correct Answer)
- C. TSH & T4
- D. T3 & T4
- E. FNAC
Explanation: ***Correct Option: TSH*** - **Thyroid-stimulating hormone (TSH)** is the most sensitive initial test to assess thyroid function when a thyroid nodule is discovered. - An abnormal TSH level (either high or low) can guide further investigation into whether the nodule is associated with a functional thyroid disorder. - **TSH should be the first test** according to American Thyroid Association guidelines for thyroid nodule evaluation. *Incorrect Option: I-131* - **I-131 (radioactive iodine therapy)** is a treatment modality for hyperthyroidism or thyroid cancer, not a diagnostic step for initial thyroid swelling evaluation. - Administering I-131 before assessing thyroid function would be inappropriate and could lead to unnecessary or harmful intervention. *Incorrect Option: TSH & T4* - While TSH is crucial, adding **T4 (thyroxine)** as an initial step is often not necessary if TSH is normal, as TSH alone effectively screens for primary thyroid dysfunction. - Measuring both TSH and T4 is typically reserved for situations where TSH is abnormal or when central hypothyroidism is suspected. *Incorrect Option: T3 & T4* - Measuring **T3 (triiodothyronine)** along with T4 as an initial screening for a thyroid nodule is generally not recommended. - T3 levels are primarily used to diagnose **hyperthyroidism** or to evaluate the severity of thyrotoxicosis after an abnormal TSH and T4 have been identified. *Incorrect Option: FNAC* - While **Fine Needle Aspiration Cytology (FNAC)** is an essential diagnostic tool for thyroid nodules, it is typically performed after TSH assessment. - FNAC is indicated for nodules >1 cm with suspicious ultrasound features, but **functional assessment with TSH comes first** to rule out hyperfunctioning nodules.
Question 3: All of the following are histological features of Hashimoto thyroiditis, except which of the following?
- A. Hurthle cell metaplasia
- B. Follicular destruction and atrophy
- C. Lymphocytic infiltrate with germinal center formation
- D. Orphan Annie eye nuclei (Correct Answer)
Explanation: ***Orphan Annie eye nuclei*** - This feature is **not seen** in Hashimoto thyroiditis; it is typically associated with **papillary thyroid carcinoma** [1][2]. - In Hashimoto thyroiditis, the presence of **Orphan Annie eye nuclei** would be considered **abnormal** and indicative of malignancy. *Hurtle cell metaplasia* - **Hurtle cells** can be found in Hashimoto thyroiditis but are not definitive; they are more associated with **thyroid follicular neoplasms**. - Presence of Hurtle cells indicates **metaplasia** but not a hallmark of Hashimoto thyroiditis specifically. *Lymphocytic infiltrate with germinal center formation* - This is a **typical histological feature** of Hashimoto thyroiditis and indicates an **autoimmune response**. - The presence of lymphocytes and germinal centers reflects **chronic inflammation** characteristic of this condition. *Follicular destruction and atrophy* - Follicular destruction is indeed a **key feature** of Hashimoto thyroiditis, leading to hypothyroidism. - Atrophic follicles occur due to **autoimmune-mediated damage**, distinct to Hashimoto thyroiditis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1099. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 429-430.
Question 4: A patient presents with neck swelling causing compression of the trachea and esophagus. Histopathological assessment reveals cell nests and pink extracellular amyloid stroma. What is the cell of origin of the tumor associated with these findings?
- A. Parafollicular C cells (Correct Answer)
- B. Hurthle cells
- C. Follicular cells
- D. Chief cells
Explanation: ***Parafollicular C cells*** - The presence of **cell nests** and **pink extracellular amyloid stroma** are classic histopathological findings for **medullary thyroid carcinoma (MTC)**, which originates from the parafollicular C cells [2], [3]. - Parafollicular C cells are responsible for producing **calcitonin**, and the amyloid in these tumors is derived from calcitonin [3]. - MTC accounts for 5-10% of thyroid cancers and can be sporadic or familial (associated with MEN 2A and 2B syndromes) [1], [4]. *Chief cells* - Chief cells are **parathyroid gland cells** that produce parathyroid hormone (PTH), not thyroid tumor cells. - While parathyroid adenomas can cause neck masses, they do not produce the characteristic amyloid stroma seen in medullary carcinoma. *Hürthle cells* - Hürthle cells (also known as Askanazy cells or oncocytes) are a type of **follicular cell** characterized by abundant **eosinophilic, granular cytoplasm** due to numerous mitochondria. - While they can form tumors (**Hürthle cell adenoma or carcinoma**), these tumors do not typically feature cell nests or amyloid stroma. *Follicular cells* - Follicular cells are the most common cell type in the thyroid and are the origin of most thyroid cancers, including **papillary** and **follicular carcinomas** [4]. - These tumors generally do not present with the characteristic **amyloid stroma** and cell nests described in the question. **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. 430-431. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-429. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 429-430.
Question 5: What is the most appropriate initial investigation for a solitary thyroid nodule (STN)?
- A. I-123 scan
- B. Ultrasound (Correct Answer)
- C. Fine-needle aspiration (FNA) biopsy
- D. Thyroid function tests (TFTs)
- E. CT scan of the neck
Explanation: ***Ultrasound*** - **Ultrasound** is the initial investigation of choice for a solitary thyroid nodule (STN) because it can differentiate between **solid, cystic, or mixed lesions**, assess nodule size, and identify suspicious features (e.g., microcalcifications, irregular margins, internal vascularity). - It also helps to determine if there are other nodules not palpable on physical examination, allowing for a more complete assessment of the **thyroid gland**. *Fine-needle aspiration (FNA) biopsy* - **FNA biopsy** is the most accurate diagnostic tool for evaluating the malignant potential of a thyroid nodule, but it is typically performed *after* an initial ultrasound has characterized the nodule. - It requires guidance (often by ultrasound) to obtain an adequate sample for cytological analysis, making ultrasound a prerequisite for optimal FNA performance. *Thyroid function tests (TFTs)* - **TFTs (TSH, T3, T4)** are important for assessing the functional status of the thyroid gland (e.g., hyperthyroidism or hypothyroidism) and can provide context for the nodule. - However, TFTs do not directly evaluate the **morphology or malignant potential** of the nodule itself, making them less appropriate as an initial, stand-alone investigation for an STN. *I-123 scan* - An **I-123 scan** (radioactive iodine uptake and scan) is used to determine if a nodule is "hot" (hyperfunctioning/benign) or "cold" (non-functioning/potentially malignant). - It is typically reserved for cases where **TSH levels are suppressed**, suggesting a hyperfunctioning nodule, and is not the first-line imaging modality for initial characterization of all STNs. *CT scan of the neck* - **CT scan** can visualize thyroid nodules and assess for extrathyroidal extension or lymphadenopathy, but it is **not recommended as an initial investigation** for STN. - It involves **radiation exposure**, is more expensive than ultrasound, and provides **less detailed characterization** of nodule morphology compared to ultrasound, making it a less appropriate first-line modality.
Question 6: What is the treatment of choice for medullary carcinoma of the thyroid?
- A. I-131 ablation
- B. Total thyroidectomy (Correct Answer)
- C. Partial thyroidectomy
- D. Hemithyroidectomy
Explanation: ***Total thyroidectomy*** - This is the **treatment of choice for medullary thyroid carcinoma (MTC)** due to its multifocal nature and high propensity for lymph node metastasis - **Complete surgical resection** (often with central compartment neck dissection) provides the best chance for cure by removing all thyroid tissue and involved lymph nodes - MTC arises from **parafollicular C cells** (calcitonin-producing cells) and frequently involves both lobes, making total thyroidectomy essential *Partial thyroidectomy* - This procedure removes only a portion of the thyroid gland, which is **insufficient for MTC** given its tendency for multifocality and bilateral involvement - Leaves residual thyroid tissue that could harbor undetected disease or develop future recurrences - Does not adequately address the aggressive nature of MTC *I-131 ablation* - **Radioactive iodine therapy** is effective for differentiated thyroid cancers (papillary and follicular) that take up iodine - MTC originates from **parafollicular C cells that do not concentrate iodine**, making I-131 ablation completely ineffective - This is a key distinguishing feature of MTC from other thyroid malignancies *Hemithyroidectomy* - This procedure removes only one thyroid lobe, which is **inadequate for MTC** - Risks leaving behind primary tumor in the contralateral lobe or occult bilateral disease - Fails to address the multifocal nature of MTC, particularly in hereditary cases (MEN 2A, MEN 2B, familial MTC)
Question 7: Treatment of resectable T4N0M0 stage of head and neck carcinoma is?
- A. Radiotherapy alone
- B. Surgery and Radiotherapy (Correct Answer)
- C. Chemoradiation
- D. Surgery alone
Explanation: ***Surgery and Radiotherapy*** - For **resectable T4N0M0 head and neck carcinoma**, the standard treatment is **surgical resection** of the primary tumor followed by **adjuvant radiotherapy**. - This approach achieves optimal **local control** for advanced primary tumors without nodal involvement. - **Adjuvant radiotherapy** is essential for T4 tumors due to high risk of microscopic residual disease and local recurrence. - Surgery allows for complete tumor removal with negative margins, while radiotherapy addresses subclinical disease. *Radiotherapy alone* - Radiotherapy alone is **insufficient as monotherapy** for T4 tumors due to the large tumor burden and extensive local invasion. - Single modality radiation cannot reliably achieve adequate tumor control for advanced primary lesions. - Generally reserved for early-stage disease or patients unfit for surgery. *Chemoradiation* - **Definitive chemoradiation** is an alternative for **unresectable T4 tumors** or when organ preservation is desired (e.g., laryngeal cancer). - For **resectable** T4N0M0 disease, surgery with adjuvant RT is preferred as it provides better local control and allows pathological staging. - Chemoradiation may be used postoperatively if high-risk features are found (positive margins, perineural invasion, extranodal extension). - In this **N0 case with resectable tumor**, upfront surgery is the preferred initial approach. *Surgery alone* - While surgical resection is crucial for T4 tumors, **surgery alone is inadequate** due to high risk of locoregional recurrence. - T4 classification indicates extensive local invasion, necessitating **adjuvant radiotherapy** to eradicate microscopic disease. - Combined modality treatment (surgery + RT) significantly improves local control and survival compared to surgery alone.
Question 8: Which of the following factors is not included in the MACIS score used for the prognosis of papillary thyroid cancer?
- A. Age
- B. Size
- C. Excision completion in surgery
- D. Mitotic index (Correct Answer)
Explanation: ***Mitotic index*** - The MACIS score is a **prognostic scoring system** for papillary thyroid carcinoma, and the mitotic index is **not a component** of this score. - The MACIS score considers factors such as **Metastasis**, **Age**, **Completeness of excision**, **Invasion**, and **Size** of the tumor. *Age* - **Age** is a crucial factor in the MACIS score, with patients older than 40 years typically having a **worse prognosis**. - It differentiates between patients <40 years and ≥40 years, assigning different points based on age. *Size* - The **size** of the primary tumor is an important component of the MACIS score. - Tumors larger than 4 cm (or 40 mm) are associated with a **higher score** and a less favorable prognosis. *Excision completion in surgery* - The **completeness of surgical excision** is a critical factor in the MACIS score. - **Incomplete tumor removal** or gross residual tumor after surgery indicates a worse prognosis and adds points to the score.
Question 9: Most common nerve injured in ligation of inferior thyroid artery
- A. Sympathetic trunk
- B. Phrenic nerve
- C. Recurrent laryngeal nerve (Correct Answer)
- D. External branch of superior laryngeal nerve
Explanation: **Recurrent laryngeal nerve** - The **recurrent laryngeal nerve (RLN)** runs in close proximity to the inferior thyroid artery, especially on the right side, making it highly vulnerable during ligation or thyroid surgery. - Injury to the RLN can cause **hoarseness** due to paralysis of the vocal cords, as it innervates most intrinsic laryngeal muscles. *Sympathetic trunk* - The **sympathetic trunk** lies more medially and posteriorly in the neck, generally not in the immediate surgical field for inferior thyroid artery ligation. - Injury to the sympathetic trunk typically leads to **Horner's syndrome** (ptosis, miosis, anhidrosis). *Phrenic nerve* - The **phrenic nerve** courses over the anterior scalene muscle, lateral to the thyroid gland and major vessels, making it relatively safe during standard thyroid surgery. - Damage to the phrenic nerve would result in **diaphragmatic paralysis** and respiratory compromise. *External branch of superior laryngeal nerve* - The **external branch of the superior laryngeal nerve (EBSLN)** is located more superiorly, running with the superior thyroid artery to the cricothyroid muscle. - Injury to the EBSLN would affect the **pitch of the voice** but is less commonly injured during inferior thyroid artery ligation compared to the RLN.
Question 10: 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
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