Respiratory Pathology Practice Questions

Q: On biopsy, a characteristic finding of malignant mesothelioma is:

Branching microvilli. ### Explanation **Correct Answer: D. Branching microvilli** **Why it is correct:** Malignant Mesothelioma is a primary tumor of the pleura, strongly associated with asbestos exposure. On **Electron Microscopy (EM)**, which is the gold standard for distinguishing it from adenocarcinoma, mesothelioma cells exhibit characteristic **long, slender, and branching microvilli**. These microvilli typically have a high length-to-diameter ratio (often >10:1). In contrast, adenocarcinoma cells show short, blunt, and non-branching microvilli. **Analysis of Incorrect Options:** * **A. Myelin:** Myelin figures are whorled phospholipid masses seen in reversible or irreversible cell injury (representing damaged membranes). They are not specific to mesothelioma. * **B. Desmosine:** This is an amino acid found in **elastin** fibers. It is a marker for connective tissue breakdown (e.g., in emphysema) but has no diagnostic role in mesothelioma. * **C. Weibel-Palade bodies:** These are storage organelles found in **endothelial cells** containing von Willebrand factor and P-selectin. They are markers for vascular tumors like angiosarcoma. **NEET-PG High-Yield Pearls:** 1. **Immunohistochemistry (IHC):** Mesothelioma is typically **Calretinin (+)**, Cytokeratin 5/6 (+), and WT-1 (+). It is **CEA (-)** (CEA is positive in adenocarcinoma) [1]. 2. **Gross Appearance:** It characteristically "encases" the lung, forming a thick, firm, grayish-white pleural rind. 3. **Asbestos Association:** While asbestos causes both, **Bronchogenic Carcinoma** is actually the *most common* cancer associated with asbestos; however, Mesothelioma is the *most specific*. 4. **Ferruginous Bodies:** These are asbestos bodies coated with iron-containing protein (Prussian blue positive) found in the lungs of exposed individuals. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 731.

Q: Collar button lesions are characteristic of which of the following conditions?

Carcinoids. **Explanation:** **Carcinoid tumors** are neuroendocrine neoplasms that typically arise from the bronchial mucosa [1]. The characteristic **"collar-button" lesion** (also known as a dumbbell lesion) occurs because these tumors often grow in a dual fashion: they have a small endobronchial component that protrudes into the airway lumen and a much larger, bulky extrabronchial component that extends into the adjacent lung parenchyma or peribronchial soft tissue. On imaging or gross specimen, the narrow neck at the bronchial wall connecting these two masses resembles a collar button. **Why other options are incorrect:** * **Adenocarcinoma:** This is typically a peripheral lung tumor that arises from surface epithelium or mucous glands. It usually presents as a solid mass or ground-glass opacity rather than a trans-mural "collar-button" growth. * **Squamous Cell Carcinoma:** While these are often central/hilar, they are characterized by endobronchial obstruction, cavitation, and local invasion. They tend to be exophytic or ulcerative rather than forming the distinct dumbbell shape seen in carcinoids. **NEET-PG High-Yield Pearls:** * **Origin:** Derived from **Kulchitsky cells** (enterochromaffin cells) of the bronchial epithelium. * **Histology:** Shows a "monotonous" appearance with organoid, trabecular, or palisading patterns and **"salt and pepper" chromatin** [1]. * **Markers:** Positive for **Chromogranin A**, Synaptophysin, and CD56. * **Clinical:** Most are non-secretory; however, if they metastasize to the liver, they can cause **Carcinoid Syndrome** (flushing, diarrhea, wheezing). * **Classification:** Divided into Typical (low grade, <2 mitoses/10 HPF, no necrosis) and Atypical (intermediate grade, 2-10 mitoses/10 HPF, focal necrosis) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 727.

Q: A 40-year-old female presented with a 3-month history of fever, loss of appetite, weight loss, cough, and weakness. A chest X-ray revealed consolidation in the upper lung. She died a few days after admission. Autopsy revealed gross lung findings and biopsy findings. What is your diagnosis?

Tuberculosis of the lung. ***Tuberculosis of the lung*** - The combination of **constitutional symptoms** (fever, weight loss, loss of appetite) with **upper lobe consolidation** on chest X-ray is classic for pulmonary tuberculosis. - Autopsy findings would show **caseating granulomas** with **caseous necrosis** and **Langhans giant cells**, pathognomonic for TB. *Sarcoidosis* - Typically presents with **non-caseating granulomas** without central necrosis, unlike the caseating pattern seen in TB. - More commonly affects **bilateral hilar lymph nodes** and lower lobes, not upper lobe consolidation as described. *Carcinoma of the lung* - Histology would show **malignant epithelial cells** and **pleomorphic nuclei**, not granulomatous inflammation. - While constitutional symptoms can occur, the **upper lobe predilection** and granulomatous response favor infectious etiology. *Bronchiectasis* - Characterized by **airway dilation** and **chronic suppurative infection**, not consolidation or granulomas. - Typically presents with **chronic productive cough** with purulent sputum, not the acute presentation described.

Question 1

Bilateral malignant pleural effusion is most often seen in which of the following conditions?

Accepted Answer

Mesothelioma

Answer

Breast carcinoma

Answer

Lung carcinoma

Answer

Lymphoma

Question 2

On biopsy, a characteristic finding of malignant mesothelioma is:

Accepted Answer

Branching microvilli

Answer

Myelin

Answer

Desmosine

Answer

Weibel-Palade bodies

Question 3

Collar button lesions are characteristic of which of the following conditions?

Accepted Answer

Carcinoids

Answer

Adenocarcinoma

Answer

Squamous cell carcinoma

Answer

None of the above

Question 4

All of the following statements about Emphysema are true, except:

Accepted Answer

Restrictive pattern on pulmonary function test is seen.

Answer

Breathlessness is the characteristic presenting symptom.

Answer

Diffusion rate of carbon monoxide is reduced.

Answer

Long term bronchodilator therapy does not improve lung function.

Question 5

What is true about Alpha-1 antitrypsin deficiency?

Accepted Answer

Severe pulmonary disease

Answer

Liver biopsy revealing PAS positive diastase sensitive granules

Answer

ZZ genotype is associated with poor prognosis

Answer

All of the above

Question 6

A 56-year-old man with a history of cigarette smoking presents with difficulty swallowing and a muffled voice. Laryngoscopy reveals a 2-cm laryngeal mass. If this mass is a malignant neoplasm, which of the following is the most likely histologic diagnosis?

Accepted Answer

Squamous cell carcinoma

Answer

Adenocarcinoma

Answer

Leiomyosarcoma

Answer

Small cell carcinoma

Question 7

Smoking is generally not associated as a risk factor with which of the following?

Accepted Answer

Bronchiolitis obliterans organizing pneumonia

Answer

Small cell carcinoma

Answer

Respiratory bronchiolitis

Answer

Emphysema

Question 8

Carcinoid tumors of the lung arise from which of the following cells?

Accepted Answer

Kulchitsky (K) cells

Answer

Type-II pneumocytes

Answer

Mucus (goblet) cells

Answer

Clara cells

Question 9

A 40-year-old female presented with a 3-month history of fever, loss of appetite, weight loss, cough, and weakness. A chest X-ray revealed consolidation in the upper lung. She died a few days after admission. Autopsy revealed gross lung findings and biopsy findings. What is your diagnosis?

Accepted Answer

Tuberculosis of the lung

Answer

Sarcoidosis

Answer

Carcinoma of the lung

Answer

Bronchiectasis

Question 10

Caplan syndrome is seen in which of the following conditions?

Accepted Answer

Pneumoconiosis

Answer

COPD

Answer

Pulmonary edema

Answer

Bronchial asthma

Respiratory Pathology — MCQs

Respiratory Pathology — MCQs

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