Pulmonary nodule

A pulmonary nodule refers to a soft tissue shadow with a diameter of ≤30 mm, surrounded by lung tissue, found on a chest X-ray or chest CT scan. Imaging shows that pulmonary nodules are round or oval, with clear or unclear boundaries with surrounding tissues. They can be single or multiple nodules. Nodules with a diameter of less than 5 mm are called pulmonary micronodules, those between 5 and 10 mm are called small pulmonary nodules, and those exceeding 30 mm are generally referred to as masses. Pulmonary nodules are common in middle-aged and elderly individuals. They are more frequently observed in long-term heavy smokers.