4 cms - is most commonly due to - Bronchial adenoma.Honey Comb appearance.SarcoidosisQ.Histiocytosis X.Interstitial king diseaseQ.TuberculosisQ.Collagen disordersQ.PneumoconiosisQ.Drugs - bleomycin, busulphan, melphalan. cyclophosphamide.Meniscus sign i Crescent sign (mobile mass in pulmonary cavity) is most commonly seen in - Aspergilloma (fungal ball lesion).Egg-Shell calcification - SilicosisQ, SarcoidosisQ, Coal miner's pneumoconiosisQ, Lymphoma following radiotherupyQ.Pop-corn calcification / Craggy pop-corn calcification - Pulmonary Hamartoma.Pleural calcification - most common cause is - Tuberculosis (Asbestosis).Diaphragmatic pleura calcification - is due to - Asbestosis.Calcification in a pulmonary metastasis - is most commomly due to - Osteosarcoma.Coin shadow in the lung (single), w ith calcification in the centre - Epidermoid carcinoma.For radiologically evident pleural effusion - the minimal amount of pleural fluid that should be present is - 250 ml.Plethoric lung fields - seen in - L-R shunts (VSD. PDA. ASD).Oligemic lung fields - Pulmonary atreisa. Stenosis; Ebstein's anomaly.Perihilar fluffy opacities - seen in - Pulmonary venous hypertension.RibsSuperior surface notch of ribs - seen in - Hyper- parathyroidsm. Neurofibromatosis, Connective tissue disorders.Inferior surface notch of ribs - seen in - Coarctation of Aorta, SVC obstruction, Chest wall AV fistula. Aortic Thrombosis.Unilateral notching of ribs - Coarctation of Left subclavian artery. Subclavian artery block, Blalock-Taussig Operation.OthersDisplacement of tracheal shadow - most common cause is - Thyroid swelling.Water Lily sign - Ruptured hydatid cyst.">