Respiratory Pathology Practice Questions

Q: Charcot-Leyden crystals are derived from which cell type?

Eosinophils. **Explanation:** **Charcot-Leyden crystals** are hallmark microscopic findings in conditions characterized by eosinophilic inflammation, most notably **Bronchial Asthma**, allergic rhinitis, and certain parasitic infections. [1] 1. **Why Eosinophils are correct:** These crystals are composed of **Galectin-10**, a protein that makes up nearly 7–10% of the total cellular protein in eosinophils. When eosinophils degranulate and undergo lysis (eosinoptosis) at the site of inflammation, the released Galectin-10 molecules aggregate and crystallize into the characteristic hexagonal, bipyramidal, needle-like shapes known as Charcot-Leyden crystals. 2. **Why other options are incorrect:** * **Basophils:** While basophils contain some Galectin-10, they are present in much smaller numbers in respiratory secretions compared to eosinophils and are not the primary source of these crystals. * **Bronchial goblet cells:** These cells are responsible for mucus production (hyperplasia leads to Curschmann spirals), not crystal formation. * **Mast cells:** These cells release histamine and leukotrienes during Type I hypersensitivity but do not contain the Galectin-10 protein required to form these specific crystals. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** Hexagonal, bipyramidal, "needle-shaped" crystals. * **Associated Finding:** Often seen alongside **Curschmann spirals** (coiled mucus plugs) and **Creola bodies** (ciliated columnar epithelial clusters) in the sputum of asthmatic patients. * **Biochemical Marker:** Remember the protein **Galectin-10** (formerly known as lysophospholipase). * **Staining:** They stain purplish-red with Romanowsky stains. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 688-689.

Q: A 45-year-old, HIV-positive patient presents with features of pneumonia. What are the characteristic histopathological features suggesting Pneumocystis jirovecii pneumonia?

Eosinophilic alveolar exudates. **Explanation:** *Pneumocystis jirovecii* pneumonia (PJP) is a classic opportunistic infection in immunocompromised patients, particularly those with HIV/AIDS (CD4 count <200 cells/µL) [1]. **1. Why Option B is Correct:** The hallmark histopathological finding of PJP is the presence of **intra-alveolar, foamy, eosinophilic (pink) exudates** [1]. This "cotton-candy" appearance is created by a mixture of the organisms (trophozoites and cysts), surfactant, and host proteins. Unlike typical bacterial pneumonia, the inflammatory response is minimal, and the exudate fills the alveolar spaces without significant cellular infiltration. **2. Why Other Options are Incorrect:** * **Option A:** While some thickening of the alveolar septa can occur, **interstitial pneumonitis** is more characteristic of viral infections (like CMV) or Mycoplasma [1]. In PJP, the primary pathology is intra-alveolar. * **Option C & D:** PJP is characterized by a **lack of a robust cellular response**. A prominent mononuclear (lymphocytic) or neutrophilic infiltrate suggests a pyogenic bacterial infection or a different fungal etiology. The "foamy" nature of PJP exudate is distinct because it is relatively acellular. **3. NEET-PG High-Yield Pearls:** * **Special Stains:** The cysts are best visualized using **Gomori Methenamine Silver (GMS)** stain, appearing as crushed ping-pong balls or "cup-and-saucer" shapes [1]. Periodic Acid-Schiff (PAS) can also be used. * **Diagnosis:** Bronchoalveolar lavage (BAL) is the gold standard for diagnosis. * **Radiology:** Classically presents with bilateral, perihilar "ground-glass" opacities. * **Treatment:** Trimethoprim-sulfamethoxazole (TMP-SMX) is the drug of choice for both treatment and prophylaxis. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 318-319.

Question 1

Emphysema is due to deficiency of?

Accepted Answer

Alpha-1 antitrypsin

Answer

Tumor necrosis factor

Answer

Prostaglandins

Answer

Leukotrienes

Question 2

Inhalation of asbestos particles of 15 micrometers will cause which of the following?

Accepted Answer

Mesothelioma

Answer

Carcinoma of the liver

Answer

Carcinoma of the larynx

Answer

Carcinoma of the colon

Question 3

In sarcoidosis, which of the following is histologically true?

Accepted Answer

Epithelioid cells with no caseation

Answer

Epithelioid cells showing caseation

Answer

Histiocytic cells with caseation

Answer

Well-differentiated histiocytic cells

Question 4

Charcot-Leyden crystals are derived from which cell type?

Accepted Answer

Eosinophils

Answer

Basophils

Answer

Bronchial goblet cells

Answer

Mast cells

Question 5

Which of the following is a marker for small cell carcinoma of the lung?

Accepted Answer

Chromogranin

Answer

Cytokeratin

Answer

Dermin

Answer

Vimentin

Question 6

In Respiratory Distress Syndrome (RDS), which cells are damaged?

Accepted Answer

Type 1 pneumocytes

Answer

Type 2 pneumocytes

Answer

Clara cells

Question 7

A 45-year-old, HIV-positive patient presents with features of pneumonia. What are the characteristic histopathological features suggesting Pneumocystis jirovecii pneumonia?

Accepted Answer

Eosinophilic alveolar exudates

Answer

Prominent interstitial pneumonitis

Answer

Prominent mononuclear cells in alveolar exudates

Answer

Neutrophilic infiltration of alveolar interstitium

Question 8

Bronchiolitis obliterans with organizing pneumonia (BOOP) is characterized histologically in the lung by:

Accepted Answer

Loose fibrous tissue within bronchioles and alveoli

Answer

Asteroid bodies in giant cells within bronchioles

Answer

Multiple rheumatoid nodules within the interstitial tissue

Answer

Numerous eosinophils within the walls of the alveoli

Question 9

A 53-year-old man presents with weakness, malaise, cough with bloody sputum, and night sweats. A chest X-ray shows bilateral apical densities, some cavitary. The patient has a history of documented exposure to Mycobacterium tuberculosis 20 years ago, and M. tuberculosis has been identified in his sputum. Which of the following best describes the expected lung pathology in this patient?

Accepted Answer

Granulomas

Answer

Dense fibrosis

Answer

Eosinophilic infiltration

Answer

Interstitial pneumonia

Question 10

What pathological findings are revealed in status asthmaticus?

Accepted Answer

Mucous plugs in small bronchioles

Answer

Suppurative endobronchial exudates

Answer

Necrosis of bronchi

Answer

None of the above

Respiratory Pathology — MCQs

Respiratory Pathology — MCQs

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