Solid lung nodules may be lung cancer, but there is generally no such thing as carcinoma in situ, which is a pathologic diagnosis and requires pathologic testing to clarify. Lung nodules are relatively common and most people are asymptomatic and found through physical examination. Solid lung nodule is an imaging manifestation of a confined higher density round-like shadow. Most solid lung nodules found in clinical practice are benign nodules, and only a few are malignant diseases. Possible diseases to consider for solid lung nodules include inflammatory nodules, tuberculous granulomas, pulmonary malignancies, inflammatory pseudotumors, lung cancer, and parasites. The final diagnosis of lung nodules is made by either puncture sampling or direct surgical resection followed by pathologic examination.