Pulmonary Pathology of Rheumatic Diseases

Introduction.

Pulmonary involvement in rheumatic disease is the most common cause of morbidity and mortality worldwide. Rheumatic diseases with pulmonary symptoms include rheumatoid arthritis, systemic lupus erythematosus (SLE), progressive systemic sclerosis, polymyositis/dermatomyositis, and Sjogren's syndrome. Patients with rheumatic disease develop pulmonary involvement years after the disease course. However, in some patients, pulmonary manifestations occur before rheumatic disease symptoms. The pulmonary symptoms can be acute, subacute, or chronic. The pulmonary involvement causes fibrosis, resulting in the tissue being thick and scarred. As a result, the absorption of oxygen into the bloodstream becomes difficult.

What Are the Risk Factors for Pulmonary Pathology of Rheumatic Diseases?

• Smokers.

• Older men.

• The genetic defect increases the risk.

• Environmental factors.

• Use of anti-inflammatory medications.

What Are the Clinical Presentations of Pulmonary Pathology of Rheumatic Diseases?

1. Pulmonary Symptoms:

• Pleuritic pain (sharp chest pain).

• The feeling of tiredness.

• Unexplained weight loss.

• Persistent dry cough.

• Shortness of breath is more pronounced during exertion.

• Respiratory failure.

Pleura disease and interstitial pneumonia are common manifestations. Involvement of large and small airways, parenchymal interstitium, vessels, and pleura are seen.

2. Rheumatic Symptoms:

• Stiffness on waking that can last 30 minutes or longer.

• Pain and swelling in joints lasting six weeks or longer.

• Joint involvement is bilateral.

• Small joints of hands, wrists, and feet may develop pain.

What Are the Pulmonary Regions Involved in Rheumatic Diseases?

1. Pleura (thin layer of tissue covering lung).

• Pleuritis (inflammation of pleura).

• Pleural effusion (build-up of fluid between pleura and chest).

• Empyema (pus-filled pleural space).

• Necrobiotic nodules (sterile cavitating lung nodules).

• Bronchopulmonary fistula.

2. Parenchyma or interstitium involvement causes interstitial lung disease. Varying degree of inflammation and fibrosis is classified as:

• Usual interstitial pneumonia (progressive scarring of lungs).

• Nonspecific interstitial pneumonia (a disorder of tissue surrounding tiny air sacs of lungs).

• Organizing pneumonia (an interstitial lung disease caused by injury).

• Diffuse alveolar damage (an acute form of interstitial lung disease).

• Rheumatoid nodules (lumps under the skin).

3. Airways - They may show predominance in inflammation or fibrosis.

• Foreign bodies.

• Obliterative bronchiolitis -Fibrosis of various stages in terminal and respiratory bronchi causing their obliteration.

• Bronchiectasis is a permanent dilation of airways caused by chronic and recurrent inflammation.

4. Vascular

• Pulmonary hypertension (high blood pressure affecting arteries in the lungs).

What Are the Rheumatic Diseases Associated With Pulmonary Symptoms?

1. Rheumatoid Arthritis

• Radiological findings

1. Reticular opacities with or without honeycomb appearance.

2. Bronchiectasis and wall thickening.

3. Parenchymal nodules.

4. Pleural effusions.

5. Chronic damage can cause obstructive or constrictive bronchiolitis.

6. Ground glass opacities and reticular lines with bibasilar (lung bases) distribution are found in the periphery of the lungs.

7. Honeycomb cysts appear in peripheral lung bases at later stages.

• Pathological findings

1. Histologically, rheumatoid nodules are seen.

2. Acute interstitial pneumonia and diffuse alveolar damage can cause sudden respiratory failure.

3. Fibrosis of the lung and honeycomb remodeling result in usual interstitial pneumonia. The condition is more common among younger patients, and cigarette smoking may be a contributing factor.

4. In subacute and chronic forms, lung biopsy reveals lymphocyte aggregates and germinal centers.

5. Lymphoid follicles are seen in the pleura and regions of parenchymal consolidation with fibrosis. The presence of lymphoid follicles strongly indicates rheumatoid arthritis.

6. Acute symptoms are vasculitis and pulmonary hemorrhage.

7. Pulmonary silicosis, associated with rheumatic arthritis, is termed Caplan’s syndrome.

8. Intrapulmonary lymph nodes become prominent and show reactive lymphoid hyperplasia.

Patients with rheumatic arthritis tend to have an acute, subacute, and chronic form of the condition in the same lungs.

2. Progressive Systemic Sclerosis

• Radiologic findings

1. Bibasilar interstitial infiltrates are present.

2. Ground glass appearance is lesser and appears in lower lobes with aspiration pneumonitis.

3. Reticular abnormalities are less coarse.

4. Pulmonary hypertension, pleural effusion, or pleural thickening are seen.

5. Esophageal dilatations occur.

• Pathological findings

1. Fibrosis or collagenization occurs uniformly in the alveolar tissue with preservation of the alveolar form.

2. In some cases, biopsy reveals temporal heterogeneity characterized by honeycomb remodeling.

3. Pulmonary hypertensive changes are seen.

4. Esophageal dysmotility is seen.

5. In rare instances, alveolar hemorrhage with capillaritis (reddish-brown patches on the skin) is seen.

3. Systemic Lupus Erythematosus

• Radiographic findings

1. Ground glass appearance is diminished.

2. Pleural thickening.

3. Pleural and pericardial effusions.

4. Linear parenchymal opacities.

5. Acute pneumonitis results in diffuse ground glass attenuation without architectural changes of lobes.

6. Pulmonary hemorrhage or vasculitis cause centrilobular nodules with ground-glass attenuation.

• Pathological findings

1. Acute lupus pneumonitis present with acute alveolitis, variable interstitial inflammation, and edema. Pleuritis is common with variable involvement of capillaritis and macrophages.

2. Diffuse alveolar hemorrhage (bleeding inside the body) occurs with or without hemoptysis (coughing blood) with capillaritis.

3. Pulmonary hypertensive vascular disease with thrombocytic lesions forms a distinctive feature of SLE lung disease.

4. Chronic cellular interstitial pneumonia with variable interstitial fibrosis is seen.

5. The pulmonary hemorrhage causes poor outcomes.

6. Pulmonary fibrosis and interstitial lymphoid pneumonia are less common.

7. Pulmonary amyloid deposition rarely occurs.

4. Polymyositis/dermatomyositis.

• Radiographic finding.

1. Lung bases are most frequently affected.

2. Ground-glass opacities and linear opacities are common.

3. Irregular interfaces and air-space consolidation are seen.

4. Parenchymal micronodules and honeycomb patterns are seen.

• Pathological findings

1. Cellular interstitial pneumonia with fibrosis.

2. Diffuse alveolar damage with usual interstitial pneumonia is seen.

3. Organizing pneumonia is the first symptom.

4. Pleuritis, Inflammatory small airway disease, and pulmonary hypertension are less common.

5. Pulmonary capillaritis is seen.

6. Increase in risk of developing lung lymphoma and carcinoma.

5. Sjogren’s Syndrome.

• Radiographic findings.

1. Lungs show mixed alveolar and interstitial infiltrates with finely reticular or nodular patterns.

2. There is an increased risk of developing marginal zone B-cell lymphoma with symptoms of pleural effusion and hilar or mediastinal lymphadenopathy.

3. Thin-walled cysts and small nodules are seen.

• Pathological findings.

1. A lung biopsy reveals bronchiolitis and follicular lymphoid hyperplasia.

2. Interstitial inflammation.

3. Interstitial fibrosis.

4. Small necrotizing granuloma.

5. Organizing pneumonia, lymphoid interstitial pneumonia, nonspecific interstitial pneumonia, and usual interstitial pneumonia are seen.

6. Lymphoproliferative diseases (lymphoma) may develop with or without amyloid deposition, and carcinomas are seen.

How to Diagnose Pulmonary Pathology of Rheumatic Diseases?

Pulmonary Involvement.

• High-resolution CT (computed tomography) scan.

• Bronchoscopy to rule out another infectious lung disease.

• Pulse oximetry.

• The pulmonary function test measures the lung's response to short exercise (6 minutes).

• Chest X-Ray.

• Lung biopsy to identify malignant changes.

• Arterial blood gas test.

Rheumatic Disease.

• RF(rheumatoid factor) test to measure the concentration of RF autoantibody in patients.

• CCP (cyclic citrullinated peptide) test to measure RA (rheumatoid arthritis) autoantibody in patients.

• Erythrocyte sedimentation rate (ESR) to determine the presence of rheumatoid arthritis.

• High levels of C-reactive protein (CRP) indicate the presence of inflammation or infection in the body.

• Complete blood count (CBC) to determine the presence of anemia.

How to Treat Pulmonary Pathology of Rheumatic Diseases?

The mainstay of treatment is to manage symptoms and halt disease progression.

• Anti-inflammatory medications.

• Steroids or immunosuppressants.

• Oxygen therapy to facilitate easy breathing.

• Pulmonary rehabilitation therapy.

Lifestyle changes by avoiding smoking and increasing physical exercises help strengthen the lungs. As a result, the management of symptoms becomes easier.

What Are the Complications of Pulmonary Pathology of Rheumatic Diseases?

• Pulmonary hypertension.

• Pleural effusion.

• Collapsed lung.

• Respiratory failure.

• Interstitial pneumonia.

What Is the Differential Diagnosis of Pulmonary Pathology of Rheumatic Diseases?

• Drug reaction-induced pulmonary manifestation in rheumatic disease.

• Infection-induced pulmonary manifestation in rheumatic disease.

Conclusion

Lung manifestations present challenges in diagnosis and management. In addition, the interlink between lung involvement and rheumatic disease still needs to be fully understood. Studies on rheumatic lung disease and the development of newer treatment modalities may aid in better treatment outcomes.