Scleroderma is a chronic autoimmune disease characterized by the immune system mistakenly attacking the body’s own connective tissues. This widespread condition can lead to hardening and tightening of the skin, but its effects extend beyond the skin, potentially impacting various internal organs. Among the organs most frequently affected are the lungs, and lung involvement is a significant health concern for individuals living with scleroderma.
Primary Lung Manifestations
Scleroderma affects the lungs primarily through two distinct conditions: Scleroderma-Associated Interstitial Lung Disease (SSc-ILD) and Scleroderma-Associated Pulmonary Arterial Hypertension (SSc-PAH). SSc-ILD involves inflammation and subsequent scarring, or fibrosis, of the lung tissue. This scarring specifically targets the interstitium, which is the delicate tissue and space surrounding the air sacs (alveoli) of the lungs. As fibrosis progresses, the lung tissue becomes thick and stiff, making it more difficult for oxygen to pass from the air sacs into the bloodstream. This condition can lead to reduced lung function, impacting the lung’s ability to expand and contract properly during breathing.
SSc-PAH, in contrast, is a type of high blood pressure that specifically affects the arteries in the lungs and the right side of the heart. In this condition, the small pulmonary arteries can narrow, stiffen, or become blocked due to inflammation and scarring within their walls. This increased resistance to blood flow makes it harder for the heart to pump blood through the lungs, leading to elevated pressure within these vessels. The right side of the heart, which is responsible for pumping blood to the lungs, must then work harder, and this increased strain can eventually lead to heart damage. It is possible for individuals with scleroderma to develop both SSc-ILD and SSc-PAH, further complicating lung health.
Recognizing Lung Involvement
Early detection of lung involvement in scleroderma is important, as symptoms can often be subtle in their initial stages. Shortness of breath, particularly when engaging in physical activity, is a common indicator of lung complications. This breathlessness may gradually worsen over time, even with minimal exertion. A persistent dry cough can also signal lung involvement, potentially becoming more pronounced with activity.
Beyond respiratory symptoms, individuals may experience fatigue, which can be a general symptom of scleroderma but is also associated with reduced lung function and the increased effort required for breathing. Chest pain or pressure may occur, particularly in cases of pulmonary hypertension, as the heart works harder to pump blood through the lungs. Swelling in the ankles or legs, known as edema, can also be a sign of increased pressure on the right side of the heart, which is a complication of SSc-PAH.
Diagnosing Lung Complications
Identifying lung complications in scleroderma involves a series of specialized tests that assess lung function and visualize lung structures. Pulmonary Function Tests (PFTs) are a group of breathing tests that measure how well the lungs are working. These tests evaluate lung volumes, such as how much air the lungs can hold, and how efficiently gases are exchanged. For instance, the forced vital capacity (FVC) measures lung volume, which can be reduced if the lungs are stiffened by scar tissue.
High-Resolution Computed Tomography (HRCT) scans of the chest provide detailed images of the lung tissue. This imaging technique can reveal the presence and extent of fibrosis and inflammation within the lungs, appearing as grey or white areas on the scan, in contrast to healthy lung tissue which appears nearly black. HRCT is particularly sensitive in detecting even mild degrees of lung involvement. An echocardiogram, an ultrasound of the heart, is commonly used to assess heart function and to screen for signs of pulmonary hypertension. This test helps determine if there is increased pressure in the pulmonary arteries.
To definitively diagnose pulmonary arterial hypertension, a right heart catheterization is often performed. This invasive procedure directly measures the blood pressure in the pulmonary arteries and within the heart chambers, providing precise information about the severity of pulmonary hypertension.
Managing Lung Disease
Managing lung complications in scleroderma involves tailored approaches depending on the specific condition, SSc-ILD or SSc-PAH. For SSc-ILD, treatment often focuses on slowing the progression of scarring and reducing inflammation. Immunosuppressive therapies, such as mycophenolate mofetil and cyclophosphamide, are commonly used to modulate the immune system’s activity. Antifibrotic drugs, like nintedanib and pirfenidone, are also available to specifically target and slow the formation of scar tissue in the lungs. Nintedanib was the first treatment approved by the U.S. Food & Drug Administration to slow the rate of decline in pulmonary function for patients with SSc-ILD.
For SSc-PAH, the goal of treatment is to relax the blood vessels in the lungs and reduce the pressure, thereby easing the strain on the heart. This is often achieved with pulmonary vasodilators, which are medications that help widen the narrowed blood vessels. Examples include endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and prostacyclin analogues.
In addition to specific medications, supportive therapies play an important role in managing both SSc-ILD and SSc-PAH. Oxygen therapy can help alleviate shortness of breath and fatigue by increasing oxygen levels in the bloodstream. Pulmonary rehabilitation programs offer exercises and education to improve lung function and overall quality of life. Lifestyle modifications, such as smoking cessation and routine vaccinations to prevent respiratory infections, are also advised. A multidisciplinary approach, involving various medical specialists, is generally recommended to provide comprehensive care for individuals with scleroderma-related lung disease.