A 19mm nodule in the middle lobe of the right lung carries a certain risk of malignancy, more serious if caused by a malignant tumor, and mostly less serious if caused by a benign disease. Normal people have left and right lungs, the left lung includes upper and lower lobes, and the right lung has upper, middle and lower lobes. Lung nodules are higher density shadows in the lungs found on imaging tests such as chest CT, and the risk of malignancy can generally be determined based on the size, density, shape, margins, and calcification of the lung nodules. If the diameter of lung nodule is larger than 8mm, the possibility of malignant tumor is increased. If the density of nodule is uneven, lobulated, rough, the edge infiltrates the surrounding tissues, or the above changes occur in the follow-up process, the solid component of the nodule is increased, the possibility of malignant tumor should be highly suspected, which is more serious, and less than will seriously affect the prognosis. If it is caused by malignant tumor, sarcoidosis, rheumatoid nodule, pneumonia, tuberculosis, etc., after surgical treatment or regular and effective anti-infection and anti-tuberculosis treatment, the nodule will gradually shrink or even disappear completely, so it is usually not serious, only a few patients with severe pneumonia and tuberculosis may have serious conditions. It is recommended that patients should consult the doctor in time and follow the medical advice for follow-up or treatment.