Secondary interstitial lung disease in childhood and adulthood associated with a connective tissue disease

Secondary interstitial lung disease (ILD) associated with connective tissue disease (CTD-ILD) is a group of pulmonary disorders that occur as a complication of underlying autoimmune connective tissue diseases. These conditions can manifest in both childhood and adulthood and involve inflammation and/or fibrosis of the lung interstitium — the tissue and space surrounding the air sacs of the lungs. Connective tissue diseases commonly associated with secondary ILD include systemic sclerosis (scleroderma), rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis/polymyositis, mixed connective tissue disease, and Sjögren syndrome. The lung involvement is considered secondary because it arises as a consequence of the systemic autoimmune process rather than as a primary lung disorder. Key symptoms include progressive shortness of breath (dyspnea), persistent dry cough, reduced exercise tolerance, and fatigue. On physical examination, bibasilar inspiratory crackles may be heard. As the disease progresses, patients may develop hypoxemia (low blood oxygen levels) and, in severe cases, pulmonary hypertension and respiratory failure. In children, the presentation may also include failure to thrive and developmental impacts due to chronic hypoxia. High-resolution computed tomography (HRCT) of the chest typically reveals patterns such as nonspecific interstitial pneumonia (NSIP), usual interstitial pneumonia (UIP), or organizing pneumonia, depending on the underlying connective tissue disease. Treatment focuses on managing both the underlying connective tissue disease and the lung involvement. Immunosuppressive therapies — including corticosteroids, mycophenolate mofetil, cyclophosphamide, azathioprine, and rituximab — are commonly used to reduce inflammation and slow disease progression. The antifibrotic agent nintedanib has been approved for progressive fibrosing ILD, including CTD-ILD with a progressive phenotype. Supportive care includes supplemental oxygen therapy, pulmonary rehabilitation, and monitoring for complications. In refractory or end-stage cases, lung transplantation may be considered. Prognosis varies widely depending on the specific connective tissue disease, the histopathological pattern of lung involvement, and the response to treatment.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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