Ground glass opacity

Ground glass opacity (GGO) is a term used in radiology to describe a specific area of increased opacity on computed tomography (CT) scans of the lungs. It is named for its resemblance to ground glass, a type of frosted glass with a cloudy appearance. Ground glass opacities are seen as hazy areas that do not obscure the underlying structures of the lung, such as the bronchial structures and pulmonary vessels.

Causes

Ground glass opacities can be caused by a variety of conditions, both benign and malignant. These include:

• Infections, such as those caused by viruses (COVID-19, influenza), bacteria, and fungi
• Interstitial lung diseases, including idiopathic pulmonary fibrosis and non-specific interstitial pneumonia
• Pulmonary edema, often due to heart failure
• Pulmonary hemorrhage
• Pneumonitis, due to radiation or drug toxicity
• Alveolar proteinosis
• Lung cancer, particularly adenocarcinoma in situ

Diagnosis

The presence of ground glass opacities is typically identified through imaging studies such as a CT scan. The pattern, distribution, and extent of GGOs can help in narrowing down the potential causes. Additional diagnostic procedures might include bronchoscopy, lung biopsy, and laboratory tests to identify infectious agents or autoimmune markers.

Management

Treatment of ground glass opacities depends on the underlying cause. For infections, appropriate antibiotics, antivirals, or antifungals are used. In cases of interstitial lung disease, management may involve the use of corticosteroids or other immunosuppressive agents. When GGOs are associated with malignancy, treatment options may include surgery, chemotherapy, or radiation therapy.

Prognosis

The prognosis for patients with ground glass opacities varies widely and depends on the underlying condition. Infections may resolve completely with treatment, while chronic conditions such as interstitial lung disease may result in progressive deterioration of lung function.

Epidemiology

The prevalence of ground glass opacities in the population is not well-defined, as they are typically incidental findings noted during imaging studies performed for other reasons. However, the incidence of GGOs has received increased attention during the COVID-19 pandemic, as they are commonly seen in patients infected with the SARS-CoV-2 virus.