Inflammation mainly appears as a thin glassy shadow, while tumor or cancer mainly appears as a soft tissue mass. Soft tissue masses are irregular in shape, well-defined, with short burrs and progressive growth, and may be combined with enlarged hilar and mediastinal lymph nodes when anti-inflammatory therapy is not effective or when enhanced CT is performed. Pneumonia may appear on CT as a thin, lamellar exudate and as an obstructive pneumonia. At the same time, inflammation can be rapidly absorbed by anti-infection treatment and does not grow progressively. These are the differences between inflammation and cancer on imaging, and the details can be clarified only by mass or pathological examination.