A patient presents with breathlessness. He has bilateral basal crepitations, lung function tests reveal a decrease in total lung capacity (TLC) and vital capacity (VC) with normal FEV1 /FVC ratio. What is the most likely diagnosis?: (A) Chronic bronchitis, (B) Idiopathic pulmonary fibrosis, (C) Cystic fibrosis, (D) Allergic bronchopulmonary aspergillosis
Answer is B. The presence of reduced TLC & VC points to Restrictive pattern and is confirmed by normal FEV1/FVC ratio. Cystic fibrosis & Chronic Bronchitis leads to Obstructive airway disease. ABPA causes central bronchiectasis and is a suppurative lung disease.