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Interstitial lung diseases are a heterogeneous group of disorders characterized by alveolar septal thickening, fibroblast proliferation, collagen deposition, and, if the process remains unchecked, pulmonary fibrosis. Interstitial lung diseases can be classified using various criteria (eg, acute vs chronic, granulomatous vs nongranulomatous, known cause vs unknown cause, primary lung disease vs secondary to systemic disease).

Among the numerous possible causes are most connective tissue disorders and occupational lung exposures and many drugs (see Environmental Pulmonary Diseases; Table 1: Interstitial Lung Diseases: Causes of Interstitial Lung Disease). A number of interstitial diseases of unknown etiology have characteristic histology, clinical features, or presentation and thus are considered unique diseases, including eosinophilic pulmonary diseases, pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis, pulmonary alveolar proteinosis, and sarcoidosis. In up to 30% of patients who have interstitial diseases with no clear cause, the processes are distinguished primarily by characteristic histopathologic features; these processes are termed the idiopathic interstitial pneumonias.

Table 1
Causes of Interstitial Lung Disease Category Examples Circulatory disorders Chronic pulmonary edema Pulmonary veno-occlusive disease Connective tissue disorders Ankylosing spondylitis Behçet's syndrome Dermatomyositis and polymyositis Goodpasture's syndrome Mixed connective tissue disease RA Sjögren's syndrome SLE Systemic sclerosis Undifferentiated connective tissue disease Drugs Amphotericin B Some Trade Names ABELCET AMBISOME AMPHOCIN AMPHOTEC Click for Drug Monograph , bleomycin Some Trade Names BLENOXANE Click for Drug Monograph , busulfan Some Trade Names MYLERAN Click for Drug Monograph , carbamazepine Some Trade Names TEGRETOL Click for Drug Monograph , chlorambucil Some Trade Names LEUKERAN Click for Drug Monograph , cocaine, cyclophosphamide Some Trade Names CYTOXAN Click for Drug Monograph , diphenylhydantoin, flecainide Some Trade Names TAMBOCOR Click for Drug Monograph , heroin, melphalan Some Trade Names ALKERAN Click for Drug Monograph , methadone Some Trade Names DOLOPHINE Click for Drug Monograph , methotrexate Some Trade Names RHEUMATREX Click for Drug Monograph , methylphenidate Some Trade Names CONCERTA RITALIN Click for Drug Monograph , methysergide, mineral oil (via chronic microaspiration), nitrofurantoin Some Trade Names FURADANTIN MACROBID MACRODANTIN Click for Drug Monograph , nitrosoureas, procarbazine Some Trade Names MATULANE Click for Drug Monograph , silicone (sc injection), tocainide Some Trade Names TONOCARD , vinca alkaloids (with mitomycin Some Trade Names MUTAMYCIN Click for Drug Monograph ) Occupational and environmental exposure Inorganic: Aluminosis (caused by exposure to metallic aluminum powder), asbestosis, baritosis, berylliosis, coal workers' pneumoconiosis, exposure to hard metals (eg, cadmium, cobalt, titanium oxide, tungsten, vanadium carbides), radiation fibrosis, siderosis, silicosis, stannosis, talc pneumoconiosis Organic: Bagassosis, bird fancier's lung, coffee worker's lung, farmer's lung, hot tub lung, humidifier lung, malt worker's lung, maple bark stripper's lung, mushroom worker's lung, tea grower's lung Infections Aspergillosis Histoplasmosis Parasitic infection Mycobacterial infection Viral infection Vasculitis Churg-Strauss syndrome Giant cell arteritis (rare) Microscopic polyangiitis Polyarteritis nodosa (rare) Takayasu's arteritis (rare) Wegener's granulomatosis Idiopathic interstitial pneumonias Acute interstitial pneumonia Cryptogenic organizing pneumonia Desquamative interstitial pneumonia Idiopathic pulmonary fibrosis Lymphocytic interstitial pneumonia Nonspecific interstitial pneumonia Respiratory bronchiolitis–associated interstitial lung disease Miscellaneous disorders Alveolar proteinosis Amyloidosis Chronic microaspiration Eosinophilic granuloma Eosinophilic pneumonia Gaucher's disease Lipoid pneumonia Lymphangioleiomyomatosis Microlithiasis Neurofibromatosis Niemann-Pick disease Pulmonary lymphoma Sarcoidosis Tuberous sclerosis

Last full review/revision May 2008 by Talmadge E. King, Jr., MD

Content last modified May 2008