Respiratory Pathology Practice Questions

Q: What is the most common benign tumor of the lung?

Hamartoma. **Explanation:** **1. Why Hamartoma is the Correct Answer:** A pulmonary hamartoma is the **most common benign tumor of the lung**. Pathologically, it is not a true neoplasm but a malformation composed of tissues normally present in the lung but arranged in a disorganized mass [1]. The most characteristic feature is the presence of **islands of hyaline cartilage**, often mixed with fat, fibrous tissue, and smooth muscle, lined by respiratory epithelium [1]. **2. Analysis of Incorrect Options:** * **B. Alveolar adenoma:** A very rare benign peripheral lung tumor. While it presents as a solitary nodule, its incidence is significantly lower than that of hamartomas. * **C. Teratoma:** These are germ cell tumors. While they can occur in the mediastinum (most common extragonadal site), primary intrapulmonary teratomas are extremely rare. * **D. Fibroma:** A benign mesenchymal tumor arising from connective tissue. It is an infrequent finding in the lung parenchyma compared to hamartomas. **3. High-Yield Clinical Pearls for NEET-PG:** * **Radiology:** Typically presents as a "coin lesion" (solitary pulmonary nodule). The classic radiological sign is **"Popcorn Calcification"** on a CT scan. * **Growth:** Most are asymptomatic, slow-growing, and discovered incidentally in patients aged 40–60. * **Genetics:** Often associated with chromosomal aberrations involving **6p21 or 12q14-15** [1]. * **Differential Diagnosis:** In the context of a solitary pulmonary nodule, the primary goal is to rule out bronchogenic carcinoma, which is the most common *malignant* tumor. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 727-728.

Q: What is the characteristic histological finding of chronic radiation pneumonitis?

Foam cells in vessel wall. **Explanation:** Radiation-induced lung injury occurs in two distinct phases: an acute phase (Radiation Pneumonitis) and a chronic phase (Radiation Fibrosis) [1]. **Why Option A is correct:** The hallmark histological feature of chronic radiation pneumonitis is **intimal thickening and subendothelial accumulation of lipid-laden macrophages (foam cells)** within the walls of small arteries and arterioles [1]. This occurs due to radiation-induced vascular endothelial damage, leading to increased permeability and lipid insudation. Over time, this progresses to obliterative endarteritis and dense interstitial fibrosis. **Analysis of Incorrect Options:** * **B. Fibroblasts in lumen:** This is characteristic of *Organizing Pneumonia* (Masson bodies), where polypoid plugs of loose connective tissue fill the distal airspaces, rather than the vessel walls. * **C. Epithelial cell hyperplasia:** While Type II pneumocyte hyperplasia occurs as a reparative response in the acute phase of radiation injury, it is a non-specific finding seen in many forms of Diffuse Alveolar Damage (DAD) [1]. * **D. Presence of giant cells in vessel wall:** This is a feature of *Giant Cell Arteritis* or certain granulomatous vasculitides (like Wegener’s), not radiation injury. **NEET-PG High-Yield Pearls:** * **Acute Phase (1–6 months):** Characterized by Diffuse Alveolar Damage (DAD), hyaline membranes, and atypical "bizarre" radiation fibroblasts [1]. * **Chronic Phase (>6 months):** Characterized by dense collagenous fibrosis, honeycombing, and the pathognomonic **foam cells in vessel walls** [1]. * **Clinical Correlation:** The severity of radiation pneumonitis is directly proportional to the dose of radiation and the volume of lung irradiated [1]. It often presents clinically as dyspnea and a dry cough. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 699-700.

Q: A 22-year-old biker sustained a severe injury in a road traffic accident. After admission to the hospital, his condition suddenly worsened, leading to death. A pathological specimen was provided. What is the likely cause of death?

Pulmonary thromboembolism. ***Pulmonary thromboembolism*** - **Sudden deterioration and death** in a young trauma patient strongly suggests **massive pulmonary embolism**, likely from a **saddle embolus** blocking the main pulmonary artery. - Post-traumatic **immobilization** and **hypercoagulable state** predispose to **deep vein thrombosis** formation, which can dislodge and cause fatal **pulmonary embolism**. *Septic shock* - Would typically develop over **hours to days** with signs of **infection** like fever, elevated white cell count, and positive blood cultures. - **Sudden death** without preceding systemic inflammatory response syndrome (SIRS) makes septic shock unlikely. *Deep vein thrombosis* - DVT itself **rarely causes sudden death**; it's the source of emboli that travel to pulmonary circulation causing fatal outcomes. - Would present as **leg swelling and pain** but doesn't explain the acute fatal deterioration. *Varicosities of the vein* - **Chronic condition** involving superficial veins with tortuous, dilated appearance, not associated with sudden death. - Does not predispose to **thromboembolism** and would not cause acute fatal complications in trauma patients.

Q: Which of the following is NOT a cavitating lesion in the lungs?

Hamartoma. **Explanation:** The correct answer is **Hamartoma**. A pulmonary hamartoma is the most common benign lung tumor, typically presenting as a well-circumscribed, peripheral "coin lesion." Pathologically, it consists of disorganized mature mesenchymal tissues (cartilage, fat, and connective tissue) [2]. On imaging, it is characterized by **"popcorn calcification"** rather than cavitation. **Why the other options are incorrect:** * **Caplan’s Syndrome:** This is the combination of Rheumatoid Arthritis and Coal Workers' Pneumoconiosis. It presents with multiple peripheral nodules (0.5–5 cm) that frequently undergo central necrosis and **cavitation**. * **Wegener’s Granulomatosis (GPA):** This small-vessel vasculitis is a classic cause of cavitating lung lesions. Approximately 50% of patients with pulmonary involvement show thick-walled, irregular **cavities** on imaging. * **Squamous Cell Carcinoma (SCC):** Among bronchogenic carcinomas, SCC is the most likely to **cavitate** (occurring in ~10–15% of cases) due to central obstructive necrosis [1]. **NEET-PG High-Yield Pearls:** * **Mnemonic for Cavitating Lung Lesions (CAVITY):** **C**ancer (Squamous cell), **A**utoimmune (Wegener’s, Caplan’s), **V**ascular (Septic emboli), **I**nfection (TB, Abscess, Fungal/Aspergilloma), **T**rauma, **Y**outh (Congenital cysts). * **Hamartoma Key Fact:** It is a "tumor-like" malformation of tissues indigenous to the site. The presence of fat and cartilage on CT is diagnostic [2]. * **Most common cause of a thin-walled cavity:** Coccidioidomycosis. * **Most common cause of a thick-walled cavity:** Squamous cell carcinoma or Lung abscess. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 336-337. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 727-728.

Question 1

What is the most common benign tumor of the lung?

Accepted Answer

Hamartoma

Answer

Alveolar adenoma

Answer

Teratoma

Answer

Fibroma

Question 2

Scar carcinoma of the lung is most commonly seen following which conditions?

Accepted Answer

Tuberculosis

Answer

Irradiation

Answer

Infarct

Answer

Lung abscess

Question 3

The mucus seen in chronic bronchitis patients is derived from which of the following cell types?

Accepted Answer

Alveolar macrophages

Answer

Goblet cells

Answer

Ciliated columnar cells

Answer

Club cells

Question 4

A 33-year-old man suddenly develops severe dyspnea with wheezing. On physical examination, his vital signs are temperature, 37°C; pulse, 95/min; respirations, 35/min; and blood pressure, 130/80 mm Hg. A chest radiograph shows increased lucency in all lung fields. Arterial blood gas analysis shows PO2, 65 mm Hg; PCO2, 30 mm Hg; and pH, 7.48. A sputum cytologic specimen shows Curschmann spirals, Charcot-Leyden crystals, branching septate hyphae, and eosinophils in a background of abundant mucus. What is the most likely risk factor predisposing him to this illness?

Accepted Answer

Cytokine gene polymorphisms

Answer

Foreign body aspiration

Answer

Inhalation of environmental inorganic dusts

Answer

Inheritance of a CFTR gene mutation

Question 5

What is the characteristic histological finding of chronic radiation pneumonitis?

Accepted Answer

Foam cells in vessel wall

Answer

Fibroblasts in lumen

Answer

Epithelial cell hyperplasia

Answer

Presence of giant cells in vessel wall

Question 6

A 65-year-old chronic smoker presented with a central lung mass with distal bronchiectasis and recurrent pneumonia. A greyish white tumor was resected. Which of the following histopathological finding is most likely to be seen?

Accepted Answer

Small cells with scant cytoplasm, ill-defined borders and hyperchromatic nuclei with nuclear moulding

Answer

Derivatives of all three germ layers are seen

Answer

Tall columnar cells with cytoplasmic and intraalveolar mucin

Answer

Palisading or rosette-like arrangement of cells separated by abundant fibrovascular stroma

Question 7

Which of the following cell types is most commonly associated with chronic allergic asthma?

Accepted Answer

TH2

Answer

TH17

Answer

TH1

Answer

TH4

Question 8

Hyaline membrane in the lung is seen in which condition?

Accepted Answer

Respiratory distress syndrome

Answer

Pulmonary edema

Answer

Pneumococcal pneumonia

Answer

Acute viral hepatitis

Question 9

A 22-year-old biker sustained a severe injury in a road traffic accident. After admission to the hospital, his condition suddenly worsened, leading to death. A pathological specimen was provided. What is the likely cause of death?

Accepted Answer

Pulmonary thromboembolism

Answer

Septic shock

Answer

Deep vein thrombosis

Answer

Varicosities of the vein

Question 10

Which of the following is NOT a cavitating lesion in the lungs?

Accepted Answer

Hamartoma

Answer

Caplan's syndrome

Answer

Wegener's granulomatosis

Answer

Squamous cell carcinoma

Respiratory Pathology — MCQs

Respiratory Pathology — MCQs

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