Thyroid Nodules — MCQs
Metastases from follicular carcinoma should be treated by:
A female presents with a 1 × 1 cm thyroid swelling. What is the next best step in management?
What is the most appropriate initial investigation for a solitary thyroid nodule (STN)?
Malignancy in a multinodular goiter is most often:-
Thyroid nodule in a 65 year old male who is clinically euthyroid is most likely to be
Which of the following thyroid carcinomas cannot be definitively diagnosed by fine needle aspiration cytology (FNAC)?
A case of solitary thyroid nodule; the investigation of choice is:
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?
Most common nerve injured in ligation of inferior thyroid artery
Which of the following factors is not included in the MACIS score used for the prognosis of papillary thyroid cancer?
Thyroid Nodules 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: 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: 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 4: Malignancy in a multinodular goiter is most often:-
- A. Papillary carcinoma (Correct Answer)
- B. Anaplastic carcinoma
- C. Follicular carcinoma
- D. Medullary carcinoma
Explanation: ***Papillary carcinoma*** - **Papillary carcinoma** is the most common type of thyroid cancer, accounting for about 80-85% of all thyroid malignancies [1], [2]. - It often arises in the setting of multifocal disease or within a **multinodular goiter**, particularly when a dominant nodule undergoes malignant transformation [2]. *Anaplastic carcinoma* - **Anaplastic carcinoma** is a very aggressive and rare form of thyroid cancer, typically presenting as a rapidly growing neck mass in elderly patients [2]. - While it can occur in a multinodular goiter, it is far less common than papillary carcinoma and carries a much poorer prognosis [2]. *Follicular carcinoma* - **Follicular carcinoma** is the second most common type of thyroid cancer (10-15%) and is often difficult to distinguish from benign follicular adenomas without surgical excision [2]. - While it can be found in a multinodular goiter, **papillary carcinoma** is still statistically more frequent in this context [1]. *Medullary carcinoma* - **Medullary carcinoma** originates from the parafollicular C cells of the thyroid and accounts for about 1-2% of all thyroid cancers [2]. - It is often associated with inherited syndromes like **Multiple Endocrine Neoplasia type 2 (MEN2)** and is distinct from tumors arising from follicular cells within a multinodular goiter [2]. **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. 429-430.
Question 5: 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 6: Which of the following thyroid carcinomas cannot be definitively diagnosed by fine needle aspiration cytology (FNAC)?
- A. Anaplastic carcinoma of thyroid
- B. Medullary carcinoma of thyroid
- C. Follicular carcinoma of thyroid (Correct Answer)
- D. Papillary carcinoma of thyroid
Explanation: ***Follicular carcinoma of thyroid*** - The definitive diagnosis of **follicular carcinoma** requires the presence of **capsular or vascular invasion**, which cannot be assessed through **fine needle aspiration cytology (FNAC)** alone [1], [5]. - FNA may show features suggestive of follicular neoplasm (e.g., hypercellularity with microfollicles), but differentiation from **follicular adenoma** requires histological examination of the excised specimen [1], [4]. *Anaplastic carcinoma of thyroid* - **Anaplastic carcinoma** is highly aggressive and characterized by **pleomorphic, bizarre cells** that are easily identifiable on FNAC [2], [5]. - The distinctive cytological features, including **spindle cells, giant cells, and rapid cellular atypia**, allow for a relatively straightforward diagnosis via FNAC [2]. *Medullary carcinoma of thyroid* - **Medullary carcinoma** cells have characteristic cytological features, such as **plasmacytoid appearance**, **amyloid deposition**, and **neuroendocrine granules**, which can be identified on FNAC [5]. - Confirmation can be made by **immunohistochemical staining for calcitonin** on the FNA sample [5]. *Papillary carcinoma of thyroid* - **Papillary carcinoma** has distinct cytological features, including **orphan Annie eye nuclei**, **intranuclear grooves**, **pseudoinclusions**, and **papillary structures**, readily identified by FNAC [3]. - These features are highly specific and often allow for a definitive diagnosis of papillary thyroid carcinoma [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1100-1101. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1101-1102. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 429-430. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-429. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 430-431.
Question 7: 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 8: 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 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: 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.
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