**Question:** Earliest lesion seen in asbestosis is

A. interstitial fibrosis
B. pleural plaques
C. thickening of the pleura
D. lung nodules

**Core Concept:** Asbestosis is a fibrotic lung disease caused by inhalation of asbestos fibers. It leads to progressive fibrosis and lung damage, resulting in impaired lung function.

**Why the Correct Answer is Right:** The correct answer, A. interstitial fibrosis, refers to the initial stage of asbestosis characterized by the accumulation of collagen in the lung interstitium. Asbestos fibers cause inflammation, followed by fibrosis and scarring of the lung tissue, leading to the development of asbestosis.

**Why Each Wrong Option is Incorrect:**

B. Pleural plaques (B): Pleural plaques are localized calcifications on the pleural surface and do not indicate the presence of fibrosis. They result from the deposition of asbestos fibers on the pleura without significant lung parenchymal involvement.

C. Thickening of the pleura (C): Pleural thickening refers to the increased thickness of the pleura without significant fibrosis, which is distinct from the early stage of asbestosis involving the lung parenchyma.

D. Lung nodules (D): Lung nodules are usually associated with asbestos-induced lung cancer and are not considered as the initial lesions in asbestosis.

**Clinical Pearl:** Asbestosis is often co-existent with other asbestos-related diseases, such as lung cancer and pleural plaques. Clinical recognition of early lesions like interstitial fibrosis is crucial for early diagnosis and appropriate management.

**Correct Answer:** D. Interstitial fibrosis (A) is the earliest lesion seen in asbestosis, representing the first stage of asbestos-induced lung fibrosis. Progression of these lesions leads to further fibrosis and lung damage, eventually causing asbestosis.