A 0.4cm mixed ground glass nodule in the sublingual segment of the upper lobe of the lung may not be serious. A 0.4cm mixed glass nodule in the lower lingual segment of the upper lobe of the lung may be due to inflammation, calcification, and fibrosis of the lung tissue, etc. The size of the nodule is relatively small at present, and if the patient does not have symptoms such as coughing and chest pain, it is usually not a big problem, and the size of the localized nodule may remain stable in later stages, and it may be gradually absorbed and dissipated. A 0.4 cm mixed glass nodule in the lower lingual segment of the upper lobe of the lung is a common finding during CT or magnetic resonance imaging, which requires attention to a light diet and regular observation of changes in the nodule tissue, and does not require special treatment. If you find 0.4cm mixed ground glass nodules in the lower lingual segment of the upper lobe of the lungs, most of the time it may be a benign localized lesion, but if the localized nodules continue to increase in size in the later stages and obvious symptoms of discomfort appear, you need to consult a doctor in time for examination.