A 56 year old man presents with non productive cough for 4 weeks. The most noticeable signs were grade III clubbing and a lesion in the apical lobe on X-ray. Most likely diagnosis is:

Clubbing, old age, non productive cough in presence of an apical (peripheral) lobe lesion is suggestive of non small cell variant of Ca lung. Cough stas as persistent cough followed later by productive cough. Ref: Harrison's Principles of Internal Medicine, 17th Education, Page 554 ; Medicine Prep Manual for U.G, K.G.M.C Agarwal, 3rd Education, Page 151