thumb<unk> , also referred to as<unk>  thickening or bronchial wall thickening, is a radiologic sign which occurs when excess fluid or mucus buildup in the small airway passages of the lung causes localized patches of atelectasis (lung collapse). This causes the area around the bronchus to appear more prominent on an X-ray. It has also been described as donut sign, considering the edge is thicker, and the center contains air. __TOC__
Peribronchial cuffing
Multifocal micronodular pneumocyte hyperplasia
Non-specific interstitial pneumonia
Ground-glass opacity
Lymphocytic interstitial pneumonia
Mediastinal fibrosis
Colloid nodule
Bronchial hyperresponsiveness