What are ground-glass nodules in the lungs?

Ground-glass nodules in the lungs are a not uncommon lung disease. Patients with this disease may find shadows or blurriness in their lungs during examination. Low alveolar air content, thick septa, and large number of cells are all complications of ground-glass nodules in the lungs. Ground-glass nodules in the lungs are mainly divided into two types, namely: typical ground-glass nodules and atypical adenomatous hyperplasia and adenocarcinoma in situ. Regardless of the type, if it is not treated in time, it will cause great pain to the patient, and the longer the delay, the more difficult the treatment will be. Therefore, if ground-glass nodules are found in the lungs, they must be treated promptly. The following is an introduction to ground-glass nodules in the lungs.

1. What are ground-glass nodules in the lungs?

Ground-glass nodules, abbreviated as GGO or GGN (ground-glass opacity/note) in English, refer to local nodular areas. The blurriness of the lungs increases, manifesting as cloudy, thin shadows/round nodules with slightly increased density. They look like frosted glass, so they are called ground-glass shadows. However, the airways, interlobar fissures, and blood vessels can still be seen through this area, which is different from the typical solid nodule. These nodules may contain solid components, which are called partially solid ground-glass nodules, while those without solid components are called pure ground-glass nodules.

GGOs are usually multiple, with characteristics different from solid nodules, tend to be malignant, and the typical histological spectrum is adenocarcinoma with a low growth rate, often demonstrating a doubling time of >2 years. Therefore, the treatment of GGO is different from that of solid nodules and needs to be discussed separately.

2. Causes of Ground-glass Nodules in the Lungs

Ground-glass changes in the lungs are mainly due to reduced alveolar gas content, a relative increase in the number of cells, thickening of the alveolar septa, and partial filling of the terminal airways. Therefore, ground-glass opacity is only a medical imaging description, and ground-glass opacity can be caused by various reasons, such as inflammatory lesions, focal fibrosis, atypical adenomatous hyperplasia (AAH), alveolar hemorrhage, etc.

Adenocarcinoma in situ (AIS) or minimally invasive adenocarcinoma (MIA) is a type of adenocarcinoma in which tumor cells grow and spread along the alveolar walls or bronchiolar walls without destroying the lung tissue structure. Therefore, they may also appear as ground-glass changes on chest CT.

Types of ground-glass nodules in the lungs

Typical ground-glass opacity is a non-solid nodule with clear edges of normal anatomical structures (such as blood vessels) inside. But it never disappears

GGN lesions are often lung cancer or precancerous lesions. Retrospective studies of a large number of GGN cases have shown that surgical resection has satisfactory results and a zero recurrence rate.

Atypical adenomatous hyperplasia and adenocarcinoma in situ usually present as pure

GGOs; however, adenocarcinoma progression may show more solid components within the GGO lesions. The development and evolution process of GGOs has gradually become clear. About 20% of pure GGOs and 40% of partial solid GGOs will gradually increase in size or their solid components will continue to increase, while other lesions may remain unchanged for many years. Should all pulmonary GGO lesions be surgically resected or should lesions that do not change require surgical resection? Because some GGN lesions can remain unchanged for many years, including those that show cancer cells under a microscope, there is currently no consensus on what surgical treatment should be used.