A carcinoma that arises from the lung and is characterized by the presence of malignant glandular epithelial cells. There is a male predilection with a male to female ratio of 2:1. Usually lung adenocarcinoma is asymptomatic and is identified through screening studies or as an incidental radiologic finding. If clinical symptoms are present they include shortness of breath, cough, hemoptysis, chest pain, and fever. Tobacco smoke is a known risk factor.