Mediastinal Disorders Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Mediastinal Disorders. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Mediastinal Disorders Indian Medical PG Question 1: The thymus is located in which part of the body?
- A. Superior mediastinum
- B. Middle mediastinum
- C. Posterior mediastinum
- D. Anterior mediastinum (Correct Answer)
Mediastinal Disorders Explanation: ***Correct: Anterior mediastinum***
- The **thymus** is primarily located in the **anterior mediastinum** (also called the prevascular compartment) [1]
- It lies behind the **sternum** and in front of the **pericardium** and great vessels [1]
- In children, the thymus is large and may extend upward into the **superior mediastinum** and inferiorly to the level of the 4th costal cartilage [2]
- In adults, the thymus undergoes **involution** but remains primarily an anterior mediastinal structure
- This is the standard classification in modern anatomy texts including **Gray's Anatomy**
*Incorrect: Superior mediastinum*
- The **superior mediastinum** extends from the thoracic inlet to the **sternal angle** (level of T4/T5)
- While the thymus may extend into the superior mediastinum, especially in children, it is **not primarily classified** as a superior mediastinal structure [2]
- Superior mediastinum contains: thymus (upper portion), great vessels (aortic arch, brachiocephalic vessels, SVC), trachea, esophagus, thoracic duct, vagus and phrenic nerves [2]
*Incorrect: Middle mediastinum*
- The **middle mediastinum** contains the **heart within the pericardium** and the **phrenic nerves** [2]
- It extends from the **sternal angle** superiorly to the **diaphragm** inferiorly
- The thymus lies **anterior** to the pericardium, not within the middle mediastinum
*Incorrect: Posterior mediastinum*
- The **posterior mediastinum** lies behind the pericardium and contains the **descending thoracic aorta**, **esophagus**, **thoracic duct**, **azygos venous system**, and **sympathetic chains**
- The thymus is located in the **most anterior** part of the mediastinum, far from the posterior compartment
Mediastinal Disorders Indian Medical PG Question 2: Which marker is used to differentiate a thymoma from acute lymphoblastic leukemia (ALL)?
- A. Cytokeratin (Correct Answer)
- B. CD1a
- C. CD3
- D. TdT
Mediastinal Disorders Explanation: ***Cytokeratin***
- **Thymomas** are epithelial tumors and express **cytokeratin**, which is a marker for epithelial cells, while **ALL** (Acute Lymphoblastic Leukemia) does not express this marker.
- The presence of **cytokeratin** indicates a **thymic origin**, differentiating it from lymphoid neoplasms like **ALL**.
*CD1a*
- This marker is primarily associated with **Hodgkin's lymphoma** and some **T-cell neoplasms**, not thymomas [2].
- The lack of expression in **ALL** makes it an unsuitable differentiator for thymomas.
*Tdt*
- **Tdt** (Terminal deoxynucleotidyl transferase) is a marker typically found in lymphoid progenitor cells, especially in **ALL**.
- Its presence would not indicate a **thymoma**, which does not express **Tdt**.
*CD3*
- While **CD3** is a marker of **T-cells** [2], it is not specific for thymomas, which can be **CD3-positive**, but it is also seen in various **lymphoid proliferations** including **ALL** [1].
- Therefore, it cannot be definitively used to distinguish between a thymoma and **ALL**.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 599-600.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, p. 598.
Mediastinal Disorders Indian Medical PG Question 3: All of the following are paraneoplastic syndromes for renal cell carcinoma except which of the following?
- A. Fever
- B. Amyloidosis
- C. Anaemia
- D. Acanthosis Nigricans (Correct Answer)
Mediastinal Disorders Explanation: Acanthosis Nigricans
- Acanthosis nigricans is primarily associated with **insulin resistance** and is not a known paraneoplastic syndrome related to renal cell carcinoma.
- Paraneoplastic syndromes typically involve **systemic effects** of tumors rather than dermatological manifestations like acanthosis nigricans.
*Fever*
- Fever can occur as a result of the body's response to tumors, including renal cell carcinoma, and is classified as a **paraneoplastic syndrome**.
- It reflects the **systemic inflammatory response** often seen with malignancies.
*Anaemia*
- Anaemia is a common paraneoplastic syndrome associated with renal cell carcinoma due to the production of **erythropoietin** or as a result of **chronic disease** [1].
- It can lead to **fatigue** and pallor in affected individuals, making it relevant to renal cancers [1].
*Amyloidosis*
- Amyloidosis can occur as a paraneoplastic syndrome in various malignancies, including renal cell carcinoma, due to **protein misfolding** states.
- It can lead to complications affecting **kidney function** and other organs, aligning it with renal cell carcinoma, though kidney tumors also frequently present with hypercalcemia [1].
Mediastinal Disorders Indian Medical PG Question 4: Which of the following is an anterior mediastinal tumor?
- A. Lymphoma
- B. Thymoma (Correct Answer)
- C. Aortic aneurysm
- D. Bronchogenic cyst
Mediastinal Disorders Explanation: ***Thymoma***
- **Thymomas** originate from the **thymus gland**, which is located in the **anterior mediastinum** [1].
- They are the **most common primary tumor** of the anterior mediastinum in adults and can be associated with **myasthenia gravis** (30-50% of cases) [1].
- Thymoma is the classic anterior mediastinal tumor and the most frequent solid mass in this compartment [1].
*Lymphoma*
- **Lymphoma** (particularly **Hodgkin lymphoma** and **primary mediastinal B-cell lymphoma**) is also a well-recognized **anterior mediastinal tumor** [1].
- It represents the second most common cause of anterior mediastinal masses, especially in younger patients [1].
- The mnemonic "4 T's" of anterior mediastinum includes "Terrible lymphoma" alongside Thymoma, Thyroid, and Teratoma [1].
- While both thymoma and lymphoma can occur in the anterior mediastinum, **thymoma is the most common primary tumor** in this location [1].
*Aortic aneurysm*
- An **aortic aneurysm** is an abnormal dilatation of the **aorta**, which is situated in the **middle and posterior mediastinum**.
- It is a vascular pathology, not a tumor, and does not arise from the anterior mediastinal compartment.
*Bronchogenic cyst*
- **Bronchogenic cysts** are congenital foregut malformations typically found in the **middle mediastinum**, often near the carina or main bronchi.
- They are fluid-filled developmental anomalies, not solid tumors of the anterior compartment.
Mediastinal Disorders Indian Medical PG Question 5: Which of the following presents as mediastinal enlargement?
- A. T-cell Acute Lymphoblastic Leukemia
- B. Hodgkin lymphoma (Correct Answer)
- C. Primary mediastinal large B-cell lymphoma
- D. Chronic Myeloid Leukemia
Mediastinal Disorders Explanation: ***Hodgkin lymphoma***
- **Hodgkin lymphoma** frequently presents with **mediastinal involvement**, particularly the **nodular sclerosis subtype**, leading to mediastinal enlargement [1].
- This enlargement is often detected on chest X-rays and can cause symptoms due to compression of nearby structures [1].
*T-cell Acute Lymphoblastic Leukemia*
- While T-cell ALL can cause a **mediastinal mass**, it is a **leukemia** typically characterized by widespread bone marrow involvement and circulating blast cells, not primarily a solid mediastinal enlargement.
- The mediastinal involvement is usually a manifestation of **thymic infiltration** by leukemic cells, but the primary disease is systemic.
*Primary mediastinal large B-cell lymphoma*
- This is a distinct subtype of **diffuse large B-cell lymphoma (DLBCL)** that **primarily arises in the mediastinum** and presents as a large mediastinal mass.
- It is histologically and clinically distinct from Hodgkin lymphoma, though both can cause mediastinal enlargement [1].
*Chronic Myeloid Leukemia*
- **CML** is a myeloproliferative neoplasm characterized by the **Philadelphia chromosome** and primarily affects the bone marrow and spleen.
- While extramedullary hematopoiesis can occur, mediastinal enlargement is not a typical or common presentation of CML.
Mediastinal Disorders Indian Medical PG Question 6: An entity of pneumothorax which leads to build up of positive pressure within the hemithorax, leading to collapse of lung, flattened diaphragm, mediastinal shift to contralateral side and eventually the venous return to the right side of heart is compromised - is known as
- A. Tension pneumothorax (Correct Answer)
- B. Haemo-pneumothorax
- C. Primary spontaneous pneumothorax
- D. Secondary spontaneous pneumothorax
Mediastinal Disorders Explanation: ***Tension pneumothorax***
- This is a life-threatening condition where air enters the pleural space but cannot exit, leading to a progressive accumulation of air and **positive pressure** [2].
- The increased intrathoracic pressure causes collapse of the ipsilateral lung, **mediastinal shift** away from the affected side, and compression of the great vessels, severely compromising **venous return** to the heart [2].
*Haemo-pneumothorax*
- This involves the presence of both **blood and air** in the pleural space, often due to trauma.
- While serious, it does not inherently involve the **one-way valve mechanism** and progressive pressure build-up characteristic of a tension pneumothorax.
*Primary spontaneous pneumothorax*
- This occurs without an underlying lung disease [1], typically due to the rupture of a **subpleural bleb** in otherwise healthy individuals [1].
- It usually does not involve the progressive pressure accumulation and hemodynamic compromise seen in a tension pneumothorax.
*Secondary spontaneous pneumothorax*
- This type of pneumothorax occurs in individuals with underlying pulmonary disease, such as **COPD** or cystic fibrosis [1].
- While often more severe than primary spontaneous pneumothorax due to compromised lung function, it generally does not involve the rapid and severe systemic compromise of a **tension pneumothorax** unless it progresses to that state.
Mediastinal Disorders Indian Medical PG Question 7: A 25-year-old woman presents with intermittent double vision and fatigue. Her symptoms are worse at the end of the day. She reports no other focal muscle weakness or sensory symptoms. On examination her eye movements, motor strength, and reflexes in the upper and lower limbs are normal. Repetitive handgrip exercises cause loss of strength in the grip. A CXR reveals an anterior mediastinal mass. Which of the following is the most likely diagnosis of the anterior mediastinal mass?
- A. lymphoma
- B. teratoma
- C. thymoma (Correct Answer)
- D. thyroid
Mediastinal Disorders Explanation: ***thymoma***
- The patient's symptoms of **intermittent double vision** and **fatigue, worsening at the end of the day**, are highly suggestive of **myasthenia gravis** [1].
- Approximately 15-20% of patients with myasthenia gravis have a **thymoma**, which is typically found as an **anterior mediastinal mass** on CXR [2].
*lymphoma*
- While lymphoma can present as an anterior mediastinal mass, it is not typically associated with the specific neurological symptoms of **myasthenia gravis**.
- Lymphoma often presents with systemic symptoms like **fever, night sweats, and weight loss**, which are not described here.
*teratoma*
- A teratoma is a germ cell tumor that can occur in the anterior mediastinum but does not typically cause **neuromuscular symptoms** like those seen in myasthenia gravis.
- They can sometimes be associated with paraneoplastic syndromes, but not usually with symptoms directly pointing to **acetylcholine receptor antibodies** [2].
*thyroid*
- An ectopic thyroid gland or thyroid mass in the mediastinum is rare and would not explain the patient's **myasthenic symptoms** [2].
- Thyroid masses are usually asymptomatic unless they cause **compression symptoms** or are hormonally active.
Mediastinal Disorders Indian Medical PG Question 8: Opsoclonus is associated with:
- A. Renal cell carcinoma
- B. Neuroblastoma (Correct Answer)
- C. Wilms tumor
- D. Retinal tumor
Mediastinal Disorders Explanation: ***Neuroblastoma***
- **Opsoclonus-myoclonus syndrome (OMS)**, characterized by rapid, chaotic eye movements (opsoclonus) and myoclonus, is a well-recognized paraneoplastic syndrome associated with **neuroblastoma** in children.
- This syndrome is thought to be caused by an **autoimmune response** against neural antigens shared by the tumor and the central nervous system [1].
*Renal cell carcinoma*
- While renal cell carcinoma can present with various paraneoplastic syndromes, **opsoclonus** is not typically associated with it.
- Common paraneoplastic syndromes for renal cell carcinoma include **polycythemia**, hypercalcemia, and hypertension [2].
*Wilms tumor*
- **Wilms tumor**, a common pediatric kidney cancer, is generally not associated with neurological paraneoplastic syndromes like opsoclonus.
- It is known for its association with certain **congenital anomalies** (e.g., aniridia, hemihypertrophy) but not opsoclonus.
*Retinal tumor*
- Retinal tumors primarily affect vision and are associated with **ocular symptoms**, such as vision loss or visual field defects.
- They do not typically cause systemic neurological paraneoplastic syndromes like **opsoclonus-myoclonus**.
Mediastinal Disorders Indian Medical PG Question 9: 21-year-old female presents with history of mild bilateral ptosis, proximal muscle weakness, and easy fatiguability. Which among the following is best in diagnosing this condition?
- A. Muscle biopsy
- B. Edrophonium test (Correct Answer)
- C. Repetitive nerve stimulation
- D. Electromyography
Mediastinal Disorders Explanation: The patient's symptoms of **mild bilateral ptosis**, **proximal muscle weakness**, and **easy fatigability** are highly suggestive of **myasthenia gravis**. [1] The **edrophonium (Tensilon) test** involves administering a short-acting acetylcholinesterase inhibitor, which temporarily improves muscle weakness in patients with myasthenia gravis, confirming the diagnosis. While muscle biopsy is helpful in diagnosing certain myopathies, it is **not the primary diagnostic test for myasthenia gravis**. Myasthenia gravis is a **neuromuscular junction disorder**, and muscle pathology is typically normal or non-specific. This neurophysiological study is indeed a valuable tool for diagnosing myasthenia gravis, showing a **decrement in muscle action potential amplitude** with repetitive stimulation. However, the **edrophonium test** is often a quicker and more direct initial diagnostic test due to its rapid and dramatic symptomatic improvement. **Electromyography (EMG)** can help differentiate between neuropathic and myopathic conditions and identify abnormalities in muscle activity. While single-fiber EMG is highly sensitive for myasthenia gravis [2], standard needle EMG is **not the most specific or definitive test** compared to the edrophonium test.
Mediastinal Disorders Indian Medical PG Question 10: A 26-year-old woman complains of early fatigue and weakness in doing strenuous activity. Her symptoms are worse near the end of the day. She appears well, muscle bulk, tone, and reflexes are normal. Handgrip strength decreases with repetitive testing.For the above patient with muscle weakness, select the most likely anatomic site for the disorder
- A. muscle
- B. neuromuscular junction (Correct Answer)
- C. peripheral nerve
- D. anterior horn cell
Mediastinal Disorders Explanation: ***neuromuscular junction***
- The **fatigability** and **end-of-day worsening** of weakness, along with the **decreased handgrip strength with repetitive testing**, are classic signs of **myasthenia gravis**, a disorder of the neuromuscular junction [1], [2].
- In myasthenia gravis, **acetylcholine receptor antibodies** block or destroy receptors at the neuromuscular junction, impairing nerve-to-muscle signal transmission [3].
*muscle*
- Primary muscle disorders (myopathies) typically present with **proximal muscle weakness** but do not usually show the characteristic **fatigability with repetitive use** or end-of-day worsening.
- Muscle bulk, tone, and reflexes would often be affected in significant primary muscle disease.
*peripheral nerve*
- Peripheral nerve disorders (neuropathies) usually cause **sensory changes** (tingling, numbness) along with motor weakness, and often present with **diminished reflexes**.
- The distinguishing feature of **fatigability with repetitive testing** is not typical of peripheral neuropathies.
*anterior horn cell*
- Anterior horn cell disorders, such as **amyotrophic lateral sclerosis (ALS)**, cause progressive weakness, muscle atrophy, and fasciculations.
- While they cause weakness, they typically do not exhibit the significant **day-to-day fluctuation** or **fatigability with repetitive use** described.
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