1. Morphology and foliar signs.
Typical nodules: lesions with a small difference between the sum of the long and short diameters and the number of trajectories of the included layers.
Atypical nodules: lesions with a large difference between the sum of the long and short diameters and the number of diameters of the included layers, manifested as wedge-shaped, long stripes, polygonal and lamellar lesions.
The typical nodule with deep lobar sign reflects the growth pattern of the lesion as an accumulation of cells, which is related to the faster and variable growth rate of each part of the malignant tumor margin as well as the intrinsic intrapulmonary findings such as connective tissue septa and secondary lung lobules that limit tumor growth.
Benign tumors have a slower cell growth rate at the margins and therefore mostly appear as superficially lobulated or non-lobulated.
The sign appears in 64.8% of the lung cancer group with a frequency of 80% and is less common in tuberculosis spheres and benign tumors, and very rarely in inflammatory nodules.
2. Tumor margin.
Clear margins were seen mainly in benign tumors, lung cancer and some tuberculosis globules, and rarely in inflammatory nodules, with a percentage of 4.2% and frequency of 10%.
Clear margins of nodules are important in supporting the peripheral type of small lung cancer. Inflammatory nodules are formed due to non-absorption or delayed absorption of inflammatory lesions in the lung. Some lesions can be combined with fibrous tissue hyperplasia and can be divided into malabsorptive pneumonia, mechanized pneumonia and inflammatory pseudotumor, so most inflammatory nodules have blurred margins, except for some inflammatory pseudotumors which have clearer margins.
3.Burr sign.
The pathological basis is related to the fibrous reaction within the tumor leading to the collection of tumors in the alveolar wall and between the lobules in a reticulated form and the tumor infiltrating the peri-tumor scaffold structure or with inflammatory reaction. This sign is more common in peripheral type lung cancer and can appear in inflammatory nodules and tuberculosis spheres, but is relatively rare, and it is rarely seen in benign tumors.
4.Sphenoidal protrusion.
It represents tumor invasion of surrounding tissues. Many studies have found that this sign is only seen in lung cancer, and sometimes it is not easily distinguished from inflammatory nodules or tuberculosis bulbs with peripheral fibrous reaction and lobular inflammation and non-tensor from images.
5. Multicystic translucency shadow.
When the translucent shadow within the nodule is difficult to determine whether it is a vacuolar sign, cavity and bronchial meteorology (circumferential), the translucent shadow within the nodule is divided into tubular and cystic. It is found that the multicystic translucent shadow within the nodule has greater value in suggesting malignant nodules, and the percentage of this sign appears in the lung cancer group is 58.8% and the frequency is 33.3%. It is relatively rare in inflammatory nodules and tuberculosis spheres, and this sign is not seen in benign nodules.
6. Calcification.
Tuberculosis bulb – misshapen tumor
7.Pleural depression and pleural thickening.
The former is important for the diagnosis of lung cancer, and this sign can also be seen in tuberculosis spheres and inflammatory nodules; pleural depression should be separated from pleural thickening adhesions, and the latter case is based on inflammatory fibrotic reaction, or tumor infiltration, which is more common in tuberculosis spheres and inflammatory nodules.
8. Satellite lesions.
In addition to lamellar exudates, small proliferative nodules and fibrous cord shadows, thickening of the bronchial wall around the nodules with bronchodilation is important in supporting the diagnosis of inflammatory and tuberculous lesions, showing percentages of 45.4% and 48.5% and frequencies of 50.0% and 53.3%, respectively, while rarely seen in lung cancer and not seen in benign tumors.
9. Pulmonary vascular encapsulation aggregation sign.
The pulmonary blood vessels around the nodule gather toward the lesion or enter the lesion, and the formation mechanism is related to the fibrogenic reaction within the tumor. Its differential significance is not obvious. Some foreign scholars have classified confined mechanized pneumonia into 3 types, one of which has a pyknotic lesion with distribution along the bronchovascular bundle.