A pulmonary nodule is defined as a solitary, well-defined nodule with a diameter less than or equal to 75px surrounded by air-containing lung tissue. Pulmonary nodules with a diameter of more than 75 px are classified as pulmonary masses. Both pulmonary nodules and pulmonary masses are classified as benign or malignant. In general, the probability of malignancy in isolated lung nodules is about 20-40%, and the probability of malignancy increases significantly with age. However, if a lung nodule is malignant, early diagnosis of the nature of the nodule and early surgical excision can lead to complete clinical cure and long-term survival, just like normal people. What is the nature of common lung nodules? The nature of lung nodules can be divided into two main categories: benign lung nodules and malignant lung nodules. 1, small pulmonary nodules: those less than 37.5px in diameter can be called small pulmonary nodules; 2, malignant nodules: half of the nodules above 50px are malignant. 3, benign nodules: most of the small nodules below 25px are benign. If an isolated lung nodule is malignant, it is usually a lung cancer, in addition to carcinoid tumor. Most benign lung nodules are tuberculosis, sarcoidosis, malignant tumor or lung abscess. Other diseases such as pulmonary atelectasis and extrathoracic lipomas can also form pulmonary nodules. What is the greatest danger of pulmonary nodules? The most important thing is to diagnose early whether the nature of the nodule is benign or malignant, and if it is malignant, it should be diagnosed as early as possible and surgically removed as soon as possible. How to confirm whether a lung nodule is lung cancer? 1.Pulmonary puncture examination with CT-guided percutaneous pulmonary puncture biopsy is an important method to confirm the benign and malignant nature of lung nodules and lung masses in clinical practice. It has extraordinary diagnostic value in determining the nature of lung nodules. 2, electromagnetic navigation system CT-guided percutaneous puncture lung biopsy under the electromagnetic navigation system can accurately locate the puncture site, reduce the number of punctures, shorten the puncture time, and reduce the CT radiation dose. Thus, it can precisely locate the lesion and obtain the pathology, but this new technique is not yet widely carried out. 3.Fiberoptic bronchoscopy can most intuitively understand the patient’s airway condition and give biopsy, puncture biopsy, etc. for the condition found, for the discovery of lung shadows for obtaining pathological diagnosis. 4.Ultrasonic bronchoscopy (EUBS) examination can provide puncture biopsy of lung nodules or lymph nodes with diameter over 25px, and its guided lymph node biopsy (EBUS-TBNA) provides a more accurate basis for lung cancer staging. 5.Thoracoscopy can be used as both an examination and a treatment means, and the accuracy of diagnosis is almost 100%. Patients not only get a clear pathological diagnosis, but also can have the nodules removed through thoracoscopy. The final diagnosis of lung nodules is confirmed by pathological examination as the gold standard, i.e. taking biopsy of lung nodules.