Non-Cancer Causes of Ground-Glass Opacity in Korea: What Your Lung CT May Be Showing

When a chest CT report mentions a ground-glass opacity (GGO), many patients in Korea immediately fear lung cancer.
But here’s the reassuring truth:

👉 Most GGOs are caused by benign, non-cancer conditions—especially when they remain stable or appear after illness, treatment, or inflammation.

Below are the most common non-cancer causes of GGOs found on lung CT scans in Korea.

1. Infections (Viral, Bacterial, Fungal)

One of the most common non-cancer reasons for GGOs is infection.

Common infectious causes in Korea:

• Viral pneumonia (including flu, COVID-19)
• Mycoplasma pneumonia
• Bacterial bronchopneumonia
• Tuberculosis-related inflammation (early stage)
• Post-infection scarring

Why this creates GGOs

Inflammation fills small airspaces with fluid or immune cells → produces the classic “hazy” GGO appearance.

Even after recovery, residual GGOs may linger for months.

2. Post-COVID or Post-Viral Lung Changes

Korea has seen many patients with long-lasting GGOs after respiratory infections.

Features:

• Patchy, bilateral GGOs
• Slowly improving over 3–12 months
• Often accompanied by mild fibrosis or scarring

These are very common and not considered dangerous unless they worsen.

3. Inflammation From Non-Infectious Causes

Not all inflammation is due to infection. Many non-infectious lung conditions can cause GGOs.

Examples:

• Hypersensitivity pneumonitis (allergy-related)
• Autoimmune lung disease (e.g., rheumatoid lung, lupus)
• Drug-induced pneumonitis (from medications or chemotherapy)
• Radiation pneumonitis
• Mild alveolar hemorrhage (tiny bleeding in air sacs)

These conditions often show:

• Diffuse hazy areas
• Improvement over time
• Response to steroids or stopping the trigger

4. Scarring and Fibrosis

Healing tissue often looks like ground-glass opacity.

Typical causes seen in Korea:

• Old infection scarring
• Post-surgical changes (after lung or chest procedures)
• Radiation therapy (especially breast or chest cancer radiation)

These GGOs may stay stable for years and remain harmless.

5. Pulmonary Edema (Fluid in the Lungs)

Lung fluid buildup can also cause widespread GGOs.

Common triggers:

• Heart failure
• Kidney disease
• Too much IV fluid
• Certain medications

These GGOs usually:

• Improve quickly after treating the underlying cause
• Are diffuse rather than focal

6. Atelectasis (Partial Lung Collapse)

Small areas of collapse can mimic GGOs.

Causes:

• Shallow breathing
• Post-surgery
• Mucus plugging
• Poor ventilation in a hospital setting

These often resolve with:

• Deep breathing exercises
• Physiotherapy
• Clearing mucus

7. Airway Disease

Inflammation of the small airways can create a ground-glass effect.

Seen in:

• Asthma
• Bronchiolitis
• Smoking-related airway disease
• Air pollution–related irritation (common in Korea during high PM2.5 days)

8. Alveolar Hemorrhage (Small-Vessel Bleeding)

Although it sounds scary, mild alveolar bleeding can happen from:

• Blood thinners
• Vasculitis
• Trauma
• Autoimmune disorders

This creates patchy GGOs that improve once the cause is treated.

9. Normal Variation or Transient Findings

Sometimes, GGOs are simply:

• Artifact from breathing motion
• Mucus
• Temporary inflammation
• Mild congestion during a cold

These often disappear on the next CT.

How to Know if Your GGO Is Non-Cancerous

More likely benign if:

• It is small
• Pure ground-glass (no solid part)
• Stable for multiple CT scans
• Appeared after infection or radiation
• You have no major cancer risk factors
• Blood tests (CEA, inflammatory markers) are normal

More concerning if:

• It develops a solid component
• It grows over time
• It has irregular shape or borders
• You have a history of cancer

Stable pure GGOs often stay harmless for many years.

Key Takeaway

Most ground-glass opacities detected on lung CT scans in Korea are NOT cancer.
They often come from infection, inflammation, scarring, or temporary lung changes—especially after COVID, colds, or radiation treatment.

Monitoring with periodic low-dose CT is usually enough unless the opacity changes.