Collagen Vascular Disease Systemic lupus erythematosus pleuritis + pleural effusions Rheumatoid arthritis (rheumatoid lung disease) pleuritis + pleural effusions also see pulmonary fibrosis (restrictive pattern) bilateral, diffuse appearance on chest radiograph progress to honeycomb lung in severe disease presentation gradual onset dyspnea end-inspiratory rales at lung base lung biopsy shows patchy interstitial lymphoid infiltrate into walls of alveolar units NOT associated with rheumatoid nodules in the lung this finding is associated with Caplan's syndrome (see Pneumoconioses ) Systemic sclerosis (scleroderma) may also present with CREST syndrome (a variant of scleroderma) interstitial fibrosis due to deposition of collagen triggered by increased TGF-beta secreting T-cells accumulating in lungs mainly involve capillaries and small arterioles may lead to pulmonary hypertension and cor pulmonale Iatrogenic Causes Drug-associated anti-cancer agents bleomycin/busulfan, methotrexate, nitrosourea, and cyclophosphamide anti-arrhythmics amiodarone Radiation-induced lung injury post-treatment pneumonitis (1-6 months following) associated with fever, dyspnea, and pleural effusions radiation fibrosis (6-12 months following) dyspnea, nonproductive cough, fine crackles, and pulmonary fibrosis on chest radiograph Occupational Causes Silicosis associated with occupational exposures of sandblasting, mining, and stone fabrication Silo filler's disease hypersensitivity pneumonitis to nitrogen oxide gases released by plant matter Byssinosis hypersensitivity penumonitis to textile dusts (including cotton, hemp, and linen) Farmer's lung hypersensitivity pneumonitis to Saccharopholyspora rectivirgula (thermophilic actinomyes) found in moldy hay type III hypersensitivity reaction with antigen-antibody complex depositing in lung can become type IV hypersensitivity reaction with chronic exposure Idiopathic Pulmonary Fibrosis Introduction most common group of idiopathic interstitial pneumonia chronic alveolitis with no known cause persistent inflammation results in fibrosis (due to fibroblast proliferation) and cyst formation that is most prominent in subpleural regions (lower lung predominantly) typically seen in men 40-70 years old requires transplant at most advanced stages Presentation dyspnea on exertion most common symptom gradual onset of dry cough subpleural cystic enlargement = "honeycomb" lung diagnosis can be made by HRCT if underlying causes excluded surgical lung biopsy shows usual interstitial pneumonia (UIP) Treatment Nintedanib receptor blocker of tyrosine kinases that mediate action of platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) Pirfenidone inhibitor of transforming growth factor-beta (TGF-beta) Pulmonary Alveolar Proteinosis Idiopathic pathology where proteinaceous material fills the avleoli can be caused by primary (idiopathic) or secondary (infectious/malignancies) causes Pathophysiology defect in clearance (macrophages) or production of surfactant macrophage defect and atypical infections sometimes seenin this pathology