A 50 year old male with dyspnea, dry cough, fatigue, anorexia, shows raised ESR, typically restrictive pattern in PFT. HRCT shows honey combing in subpleural zone and basal locations: Probable diagnosis is:

Idiopathic pulmonary fibrosis (i) Idiopathic pulmonary fibrosis - Earliest finding on HRCT bilateral, basal ground glass shadowing fine nodular pattern, then coarse linear shadow. Progressive pulmonary volume loss with honey combing. (ii) Sarcoidosis:- Multiple small irregular nodular opacities predominantly in midzones of lung with bilateral hilar and right para tracheal lymphadenopathy. Finally - Pulmonary fibrosis. (iii) Asbestosis: Symptoms occur after 20-30 yrs of exposure, changes in pleura & lung parenchyma are premalignant. (a) Pleural changes:- Plaque-bilateral, present in mid zones, on diaphragm which calcify sometimes resembling "Holly leaves". Effusion :- Small. When large, underlying carcinoma or mesothelium should be suspected. (b) Parenchymal changes :- Plain X-ray Reticular nodular shadow in lower zones with shaggy hea, areas of emphysema. HRCT :- Fibrosis in periphery of lung extending inwards to cause distoion of lung. (iv) Lymphangitis carcinomatosa :- Nodular thickening of the interlobular septa and thickening of the centrilobular bronchovascular bundles.