A pulmonary ground-glass nodule is an imaging concept that refers to a nodule that appears as a mildly increased density, cloudy density shadow on thin-section CT, within which the bronchial and vascular texture can still be visualized.
They are commonly seen in patients with tumors, infections, local bleeding, or interstitial fibrosis. Pulmonary ground-glass nodules may be lung tumors, inflammation, or specific infections. According to the size and nature of the nodules, they can be classified into three types: pure ground-glass nodules, partially solid nodules, and solid nodules. Most of them manifest as benign lesions, well-differentiated adenocarcinoma in situ, microinvasive adenocarcinoma, and infiltrative adenocarcinoma in terms of tissue.
In benign lesions, the boundaries of ground-glass nodules are relatively clear, and the texture is relatively homogeneous, with no obvious burrs, lobes or vacuoles.
Adenocarcinoma in situ is typically visualized as a pure ground-glass nodule with a diameter greater than 5 mm and less than 30 mm. For suspected adenocarcinoma in situ, follow-up with thin-section CT of the chest or, in selected cases, restrictive lung resection not exceeding segmental resection is recommended.
Microinvasive adenocarcinoma is a persistent, pure ground-glass nodule greater than 10 mm in diameter or a partially solid nodule. Restrictive pneumonectomy or lobectomy is recommended for suspected microinvasive adenocarcinoma.
Non-calcified solid nodules without typical benign nodal features, with a diameter greater than 8 mm and a burr sign at the border, are considered malignant. For suspected invasive adenocarcinoma, a reasonable surgical approach is recommended based on whether the lesion contains a ground-glass component, location, size, number, and the patient’s physical condition.