Respiratory Pathology Practice Questions

Q: What is a newer inclusion in the 2015 WHO classification of squamous cell carcinoma of lung?

Nonkeratinizing variant. ### Explanation The **2015 WHO Classification of Lung Tumors** introduced significant changes to the subtyping of Squamous Cell Carcinoma (SCC) to improve diagnostic reproducibility and align with molecular pathology. **Why the correct answer is right:** In the 2015 update, the classification of Squamous Cell Carcinoma was simplified into three main variants: 1. **Keratinizing SCC:** Shows obvious keratinization (pearls/individual cell keratinization). 2. **Non-keratinizing SCC:** Shows squamous differentiation (intercellular bridges) but lacks overt keratinization. This is the **newer inclusion** and is diagnosed when the tumor is solid but expresses squamous markers (p40, p63, CK5/6). 3. **Basaloid SCC:** A variant where the basaloid component exceeds 50%. **Why the other options are wrong:** * **Clear cell and Papillary variants (Options A & B):** These were recognized in the older 2004 WHO classification but were **deleted** in 2015. They are now considered "morphological features" rather than distinct subtypes because they lacked clinical or prognostic significance. * **Adenocarcinoma variant (Option C):** This is not a variant of SCC. If a tumor shows both squamous and glandular differentiation, it is classified as **Adenosquamous Carcinoma** [1]. **High-Yield NEET-PG Pearls:** * **Most common site:** SCC is typically **central/hilar** in location and strongly associated with **smoking** [1]. * **IHC Markers:** The most specific marker for SCC is **p40** (superior to p63). It is also positive for **CK5/6**. * **Paraneoplastic Syndrome:** SCC is most commonly associated with **Hypercalcemia** due to the secretion of Parathyroid Hormone-related Protein (PTHrP). * **Cavitation:** Among lung cancers, SCC is the most likely to undergo central necrosis and **cavitation**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 721-723.

Q: Thickening of the pulmonary alveolar-capillary membrane is seen in which of the following conditions?

Pulmonary fibrosis. **Explanation:** The **alveolar-capillary membrane** (blood-air barrier) is the structure through which gas exchange occurs. It consists of the alveolar epithelium, the fused basement membrane, and the capillary endothelium. **Why Pulmonary Fibrosis is correct:** Pulmonary fibrosis is the hallmark of **Interstitial Lung Diseases (ILD)**. It involves chronic inflammation and the excessive deposition of collagen and extracellular matrix within the alveolar walls (interstitium) [1]. This pathologically **thickens the membrane**, increasing the diffusion distance for oxygen and carbon dioxide, leading to a "diffusion defect" and restrictive lung disease [1]. **Why the other options are incorrect:** * **Asthma:** A chronic inflammatory airway disease characterized by reversible bronchoconstriction and hypertrophy of bronchial smooth muscle. It affects the **conducting airways**, not the alveolar-capillary membrane. * **Bronchitis:** Specifically chronic bronchitis involves mucus gland hyperplasia and inflammation of the **bronchi**. While it causes airway obstruction, it does not primarily thicken the gas-exchange membrane. * **Emphysema:** Characterized by the **destruction** of alveolar walls and permanent enlargement of airspaces. Rather than thickening the membrane, it results in a loss of surface area for gas exchange. **High-Yield Clinical Pearls for NEET-PG:** * **Diffusion Capacity (DLCO):** In pulmonary fibrosis, DLCO is **decreased** due to the increased thickness of the membrane. * **Radiology:** Look for "Honeycombing" and "Ground-glass opacities" on HRCT, which are classic signs of advanced fibrosis [1]. * **Spirometry:** Pulmonary fibrosis shows a **Restrictive pattern** (Decreased FVC, Normal or Increased FEV1/FVC ratio) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 691-695.

Q: All are true about silicosis except?

The lower lobe is usually involved. Silicosis is a chronic fibrotic lung disease caused by the inhalation of crystalline silicon dioxide [1]. **Why Option C is the correct answer (False statement):** Unlike asbestosis, which primarily affects the lower lobes [1], **silicosis predominantly involves the upper lobes** of the lungs [1]. The inhaled silica particles are ingested by alveolar macrophages, which then release inflammatory cytokines, leading to the formation of characteristic silicotic nodules in the upper zones and hilar lymph nodes. **Analysis of other options:** * **Option A (Birefringent crystals):** Under polarized light, silica particles appear as weakly birefringent (doubly refractive) crystals. This is a classic histopathological finding. * **Option B (Pleural plaques):** While more characteristic of asbestosis [1], pleural plaques can occasionally be seen in silicosis. However, the more classic pleural finding in silicosis is pleural thickening or adhesions. * **Option D (Most common pneumoconiosis):** Silicosis is globally recognized as the most common chronic occupational lung disease [1], particularly in industries like mining, sandblasting, and stone cutting [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Eggshell Calcification:** A pathognomonic radiological finding where hilar lymph nodes show peripheral calcification. * **TB Association:** Silicosis patients have a **3-fold increased risk** of developing Tuberculosis (Silicotuberculosis) because silica impairs macrophage function [1]. * **PMF:** Progression can lead to Progressive Massive Fibrosis (PMF), where nodules coalesce into large scars [1]. * **Caplan Syndrome:** The association of silicosis (or coal worker's pneumoconiosis) with Rheumatoid Arthritis [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 695-699.

Q: What are the characteristic features of Pneumocystis jirovecii pneumonia (PCP)?

All of the above. **Explanation:** *Pneumocystis jirovecii* is an opportunistic fungal pathogen that primarily affects immunocompromised individuals [1], particularly those with HIV/AIDS (CD4 count <200 cells/µL). The pathogenesis and histopathology of PCP are high-yield topics for NEET-PG. 1. **Damage to Type I Pneumocytes:** The organism attaches specifically to Type I pneumocytes. This attachment causes direct cellular injury, leading to increased alveolar-capillary permeability and impaired gas exchange. 2. **Eosinophilic Exudate:** As a result of the injury, a characteristic "cotton-candy" or "honeycomb" intra-alveolar exudate accumulates [1]. This is a proteinaceous, eosinophilic material that contains the proliferating organisms and cellular debris. 3. **Interstitial Pneumonitis:** While the exudate is intra-alveolar, the underlying host response involves the thickening of the alveolar septa with mononuclear infiltrates (plasma cells and lymphocytes), leading to an interstitial pattern on imaging. **Why "All of the above" is correct:** The disease process is a triad of direct cellular damage (Type I pneumocytes), the resulting inflammatory response in the septa (interstitial pneumonitis), and the accumulation of the characteristic fluid (eosinophilic exudate). **High-Yield Clinical Pearls for NEET-PG:** * **Stains:** Silver stains (Grocott-Gomori Methenamine Silver - **GMS**) are the gold standard to visualize the crushed-cup or boat-shaped cysts [1]. **PAS stain** also highlights the cysts. * **Radiology:** Classically presents as bilateral, perihilar "ground-glass opacities" (GGO). * **Diagnosis:** Bronchoalveolar lavage (BAL) is the preferred diagnostic procedure. * **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

What is a newer inclusion in the 2015 WHO classification of squamous cell carcinoma of lung?

Accepted Answer

Nonkeratinizing variant

Answer

Clear cell variant

Answer

Papillary cell variant

Answer

Adenocarcinoma variant

Question 2

Which of the following types of emphysema is most commonly associated with chronic smoking?

Accepted Answer

Centriacinar emphysema

Answer

Panacinar emphysema

Answer

Irregular emphysema

Answer

Mixed variety emphysema

Question 3

Thickening of the pulmonary alveolar-capillary membrane is seen in which of the following conditions?

Accepted Answer

Pulmonary fibrosis

Answer

Asthma

Answer

Bronchitis

Answer

Emphysema

Question 4

All are true about silicosis except?

Accepted Answer

The lower lobe is usually involved

Answer

Bifringent crystals are seen

Answer

Pleural plaque is seen

Answer

It is the most common pneumoconiosis

Question 5

A 70-year-old man, with a 10-15 year history of working in an asbestos factory, has a mass detected in the right apical region of his lung on a routine X-ray. A biopsy was taken from the mass. What is seen on electron microscopic examination of the biopsy?

Accepted Answer

Numerous long, slender microvilli

Answer

Neurosecretory granules in the cytoplasm

Answer

Melanosomes

Answer

Desmosomes

Question 6

Which type of lung malignancy is known to produce ACTH-like substances?

Accepted Answer

Small cell lung carcinoma

Answer

Squamous cell carcinoma

Answer

Large cell carcinoma

Answer

Oat cell carcinoma

Question 7

A radiographic study of inhalational lung diseases is conducted. One pattern of involvement is seen in persons whose total lung capacity, diffusing capacity, and compliance are decreased. This pattern consists of numerous bilateral nodular opacifications on chest radiographs. Polarizable needlelike crystals are seen on microscopic examination of these nodules. What inhaled substance is most likely to produce these findings?

Accepted Answer

Silica dust

Answer

Cigarette smoke

Answer

Mold spores

Answer

Sulfur dioxide

Question 8

What are the characteristic features of Pneumocystis jirovecii pneumonia (PCP)?

Accepted Answer

All of the above

Answer

Interstitial pneumonitis

Answer

Eosinophilic exudate

Answer

Damage to Type I pneumocytes

Question 9

A 45-year-old man has had progressive dyspnea on exertion with fatigue for the past 2 years. On auscultation of his chest, he has a prominent pulmonary component of S2, a systolic murmur of tricuspid insufficiency, and bruits over peripheral lung fields. Jugular venous distension is present to the angle of his jaw when sitting. Laboratory studies show antiphospholipid antibodies. CT angiography shows eccentric occlusions in the pulmonary arteries and mosaic attenuation of pulmonary parenchyma. Which of the following is the most likely disease process causing his pulmonary disease?

Accepted Answer

Thromboembolism

Answer

Atherosclerosis

Answer

Pneumonitis

Answer

Sarcoidosis

Question 10

A patient presents with recurrent episodic diarrhea, triggered by food or alcohol. During episodes, he experiences flushing, wheezing, and malaise. A chest x-ray reveals a lung mass. Which of the following would MOST likely be present on biopsy of the lesion?

Accepted Answer

Carcinoid tumor

Answer

Bronchioloalveolar carcinoma

Answer

Primary tuberculosis

Answer

Recurrent tuberculosis

Respiratory Pathology — MCQs

Respiratory Pathology — MCQs

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