A 50 year old man , heavy smoker complained of persistent nonproductive cough observed gain of weight especially in the trunk over the past 5 months . The chest x ray shows an ill defined 3 cm mass involving the right hilum of the lung. Cytological examination of the bronchial washings from bronchoscopy revealed round to oval cells with little cytoplasm and increased mitotic figures. He was advised to stop smoking and begin a course of chemotherapy. Which is the possible diagnosis?
A.Adenocarcinoma
B.Large cell carcinoma
C.Squamous cell carcinoma
D.Small cell carcinoma
Ans: D.Small cell carcinoma