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interstitial lung disease; diffuse parenchymal lung disease (DPLS, ILD)

Interstitial lung diseases are a heterogenous group of disorders. 'diffuse parenchymal lung disease' may be a more appropriate term since these diseases are NOT restricted to the pulmonary interstitium, & not all interstitial tissue is necessarily affected [2] Etiology: 1) occupational or environmental inhalants a) dusts - organic - inorganic b) gases, fumes - oxygen toxicity - chlorine gas - ammonia c) occupational lung disease (pneumoconiosis) - coal worker's pneumoconiosis - silicosis - asbestosis - berylliosis 2) drugs a) cytotoxic agents: methotrexate, busulfan, bleomycin b) amiodarone c) nitrofurantoin d) gold e) cocaine f) EGFR inhibitors (erlotinib, gefitinib ...) 3) radiation (6 weeks to months after radiation therapy) 4) infections (interstitial pneumonia) a) viral, bacterial, fungal, parasites b) non-specific interstitial pneumonia c) lymphocytic interstitial pneumonia 5) hypersensitivity pneumonitis 6) pulmonary edema a) cardiogenic b) non-cardiogenic 7) neoplasms a) lymphangitic spread of carcinoma b) carcinoma c) lymphoma d) alveolar carcinoma 8) metabolic causes 9) sarcoidosis 10) idiopathic pulmonary pneumonitis a) idiopathic pulmonary fibrosis (cryptogenic fibrosing alveolitis) b) acute interstitial pneumonia c) cryptogenic organizing pneumonia 11) connective tissue disease a) rheumatoid arthritis b) polymyositis, dermatomyositis c) scleroderma 12) pulmonary vasculitis 13) pulmonary hemorrhage a) Goodpasture's syndrome b) idiopathic hemosiderosis 14) eosinophilic granuloma 15) pulmonary alveolar proteinosis 16) amyloidosis 17) pulmonary veno-occlusive disease 18) microlithiasis 19) inherited disorders a) tuberous sclerosis b) Hermansky-Pudlak syndrome c) neurofibromatosis d) metabolic storage disease e) familial hypocalciuric hypercalcemia 20) lymphangioleiomyomatosis 21) bronchiolitis obliterans 22) respiratory bronchiolitis 23) chronic eosinophilic pneumonia 24) smoking-related a) pulmonary Langerhans cell granulomatosis b) desquamative interstitial pneumonia c) respiratory bronchiolitis-associated interstitial lung disease d) smoking-related interstitial fibrosis 25) chronic pulmonary aspiration Pathology: - varying degrees of inflammation & fibrosis - irreversible disruption of alveolar architecture & impaired gas exchange - no evidence of granulomatous or vascular disease in the pulmonary parenchyma Clinical manifestations: 1) insidious onset with progressive course (> 6 months) - subacute to chronic 2) exertional dyspnea, breathlessness 3) non-productive cough 4) acute presentation with fever suggests BOOP, drug-induced pulmonary injury or hypersensitivity pneumonitis 5) crackles a) fibrosing interstitial lung disease b) idiopathic pulmonary fibrosis c) less common in sarcoidosis 6) mid-inspiratory squeaks: bronchiolitis 7) signs of pulmonary hypertension a) increased intensity of P2 heart sound b) right ventricular lift c) pansystolic murmur of tricuspid regurgitation 8) clubbing a) idiopathic pulmonary fibrosis (30%) b) uncommon in: 1] bronchiolitis obliterans 2] cryptogenic organizing pneumonia 3] connective tissue disease 9) erythema nodosum a) sarcoidosis b) inflammatory bowel disease c) Behcet syndrome 10) maculopapular exanthem a) sarcoidosis b) amyloidosis c) Behcet syndrome 11) uveitis &/or conjunctivitis a) sarcoidosis b) Behcet's syndrome c) inflammatory bowel disease d) anklyosing spondylitis 12) lacrimal gland or salivary gland enlargement a) sarcoidosis b) scleroderma 13) lymphadenopathy, hepatomegaly a) sarcoidosis b) amyloidosis 14) arthritis a) connective tissue disease b) inflammatory bowel disease c) sarcoidosis d) Behcet's syndrome e) ankylosing spondylitits 15) muscle weakness or myalgias: polymyositis 16) neurologic signs/symptoms a) cranial nerve palsy (sarcoidosis) b) mental retardation (tuberous sclerosis) c) lymphoid granulomatosis 17) interstitial lung diseases that can present acutely a) pulmonary vasculitis b) acute interstitial pneumonia c) eosinophilic pneumonia Laboratory: 1) arterial blood gas: variable 2) complete blood count (CBC) 3) chemistry panel (chem7) 4) erythrocyte sedimentation rate (ESR) & serum C-reactive protein 5) serology (suspicion of rheumatologic disease) a) antinuclear antibody (ANA) b) rheumatoid factor (RF) & anti-CCP in serum c) anti-neutrophil cytoplasmic antibody (ANCA) d) serology for hypersensitivity pneumonitis 6) myositis panel a) serum creatine kinase b) anti-Jo1 antibodies c) serum TSH 7) serum BNP 8) urinalysis [2] * also see ARUP consult [] Special laboratory: 1) pulmonary function tests a) variable, but often restrictive pattern b) reduced DLCO c) abnormal alveolar-arterial oxygen gradient at rest or with exertion d) airflow obstruction with or without restriction suggests: - sarcoidosis, hypersensitivity pneumonitis, Langerhans'cell granulomatosis, respiratory bronchiolitis, COPD, lymphangioleiomyomatosis 2) tissue diagnosis generally not necessary with high-resolution CT [2] a) fiberoptic bronchoscopy b) open lung biopsy c) obtain tissue for pathology prior to initiation of: 1] glucocorticoid therapy 2] immunosuppressive therapy d) histology must be interpreted with architectural pattern from radiology, laboratory data & clinical findings 3) echocardiogram [2] (pulmonary artery pressure) 4) exercise stress testing (physiologic response to exercise) - SaO2 desaturation > 4% with ambulation [2] Radiology: 1) non-contrast high resolution computed tomography (CT) of chest a) imaging procedure of choice [2] - gold standard for evaluation of interstitial lung disease b) more sensitive & specific for diagnosis of interstitial lung disease than chest X-ray c) little role for conventional CT (5 mm slice) [2] d) pseudoreticulation is a false-positive finding due to atelectasis in gravity-dependent lung regions e) mediastinal &/or hilar lymphadenopathy with sarcoidosis f) pleural effusion (asbestosis, connective tissue disease) g) pleural plaques (asbestosis) h) obtain prior to lung biopsy 2) chest radiograph: a) variable -> bilateral infiltrates b) not predictive of specific pathologic picture, thus of limited utility [2] - a normal chest X-ray does not rule out diffuse parenchymal lung disease [2] c) predominantly upper lobe interstitial infiltrates 1] pneumoconiosis 2] silicosis 3] berylliosis 4] Langerhan's cell granulomatosis 5] sarcoidosis 6] ankylosing spondylitis d) predominantly lower lobe infiltrates 1] idiopathic pulmonary fibrosis 2] connective tissue disorders 3] asbestosis 4] chronic hypersensitivity pneumonitis e) bilateral hilar lymphadenopathy suggests sarcoidosis Complications: - acute respiratory worsening is most often a result of infection or edema [2] Management: 1) treat underlying etiology if known - smoking cessation [2] 2) assessment for connective tissue disease 3) serial evaluation of disease activity: a) progression of disease b) effects of therapy 4) inhaled treprostinil improves exercise capacity from baseline, assessed by a 6-minute walk test in patients with pulmonary hypertension due to interstitial lung disease [10] 5) supplemental O2 >=15 hours/day when hypoxemia (SaO2 <=88% on room air) [9] - ambulatory oxygen therapy if exertional hypoxemia [9] - portable liquid oxygen is best 6) pulmonary rehabilitation 7) evidence for use of glucocorticoids is weak [2] 8) lung transplantation for younger patients with severe restrictive lung disease

Related

familial hypocalciuric hypercalcemia glycogen storage disease (glycogenosis) Hermansky-Pudlak syndrome lymphangioleiomyomatosis neurofibromatosis (von Recklinghausen's disease) pulmonary aspiration; foreign body aspiration sarcoidosis tuberous sclerosis (Bourneville disease, epiloia)

Specific

bronchiolitis obliterans; constrictive bronchiolitis; cryptogenic organizing pneumonia; bronchiolitis obliterans with organizing pneumonia (BOOP) drug-induced interstitial lung disease eosinophilic pneumonia; Andrews syndrome; pulmonary eosinophilia hypersensitivity pneumonitis; extrinsic allergic alveolitis; pigeon breeder's lung; bird fancier's lung; farmer's lung; allergic pneumonitis interstitial pneumonia occupational lung disease pleuroparenchymal fibroelastosis pulmonary fibrosis pulmonary interstitial emphysema respiratory bronchiolitis associated interstitial lung disease; desquamative interstitial pneumonia (RBILD)

General

lung disease

References

  1. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 253-56
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2009, 2012, 2015, 2018, 2022. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  3. Connors GR, Christopher-Stine L, Oddis CV, Danoff SK Interstitial lung disease associated with the idiopathic inflammatory myopathies: what progress has been made in the past 35 years? Chest. 2010 Dec;138(6):1464-74. doi: 10.1378/chest.10-0180. PMID: 21138882
  4. Antoniou KM, Margaritopoulos GA, Tomassetti S et al Interstitial lung disease. Eur Respir Rev. 2014 Mar 1;23(131):40-54. Review. PMID: 24591661 Free Article
  5. Suliman S, Al Harash A, Roberts WN, Perez RL, Roman J. Scleroderma-related interstitial lung disease. Respir Med Case Rep. 2017 Jul 15;22:109-112. PMID: 28761806 Free PMC Article
  6. Walsh SL, Hansell DM. High-resolution CT of interstitial lung disease: a continuous evolution. Semin Respir Crit Care Med. 2014 Feb;35(1):129-44. Review. PMID: 24481766
  7. Meyer KC. Diagnosis and management of interstitial lung disease. Transl Respir Med. 2014 Feb 13;2:4. eCollection 2014. Review. PMID: 25505696 Free PMC Article
  8. ARUP Consult: Interstitial Lung Diseases The Physician's Guide to Laboratory Test Selection & Interpretation https://www.arupconsult.com/content/interstitial-lung-diseases
  9. Jacobs SS, Krishnan JA, Lederer DJ, et al. Home Oxygen Therapy for Adults with Chronic Lung Disease. An Official American Thoracic Society Clinical Practice Guideline Am J Respir Crit Care Med. 2020 Nov 15;202(10):e121-e141 PMID: 33185464 https://www.atsjournals.org/doi/full/10.1164/rccm.202009-3608ST - Ekstrom M et al. Long-term oxygen therapy for 24 or 15 hours per day in severe hypoxemia. N Engl J Med 2024 Sep 19; 391:977. PMID: 39254466 https://www.nejm.org/doi/10.1056/NEJMoa2402638
  10. Waxman A, Restrepo-Jaramillo R, Thenappan T et al Inhaled Treprostinil in Pulmonary Hypertension Due to Interstitial Lung Disease. N Engl J Med 2021. Jan 13, PMID: 33440084 https://www.nejm.org/doi/full/10.1056/NEJMoa2008470 - Taichman DB Optimism for Interstitial Lung Disease-Associated Pulmonary Hypertension? N Engl J Med 2021. Jan 13, PMID: 33440083 https://www.nejm.org/doi/full/10.1056/NEJMe2033181
  11. NEJM Knowledge+