Interstitial Lung Disease¶
Pakinam Mekki
Background¶
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Heterogenous group of parenchymal lung diseases that involve scarring or fibrosis, affecting the lung interstitium, alveoli, and pulmonary capillaries
- Leads to loss of lung volume and compliance and impaired gas exchange
Etiologies¶
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ILD is divided into primary (idiopathic) causes and secondary causes
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Idiopathic: idiopathic pulmonary fibrosis, eosinophilic pneumonia, idiopathic NSIP, organizing pneumonia, acute interstitial pneumonia, etc
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Secondary
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Systemic:
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Connective tissue disease: RA, Sjogrens, dermatomyositis, polymyositis SLE, MCTD, scleroderma
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Granulomatous disease: sarcoidosis, TB
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Vasculitis: granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, amyloidosis, lymphangioleiomyomatosis
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Exposure
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Pneumoconiosis (inorganic) – exposure to coal mines, silica, asbestos, organic solvents, heavy metals, solder, hair dressing chemicals
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Hypersensitivity pneumonitis (organic)- farm exposures, chicken coops, pesticide, stored grains, mold (ex: water damage in home, hot tubs)
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Iatrogenic – amiodarone, immunotherapies, TKI, TNF-a inhibitors, nitrofurantoin, radiation
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Evaluation¶
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Dry cough is the most common symptom of ILD. Productive coughs are uncharacteristic
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History:
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Duration, timing, severity of respiratory symptoms
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Exposures – pets, occupation, residence, smoking, drugs, travel, hobbies, dust, hay, grass,
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Screen for autoimmune symptoms (arthritis, myalgia, rash, Raynaud’s phenomenon
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Screen for vasculitis symptoms: hematuria, hemoptysis, mononeuritis multiplex
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Medication history
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Family history – premature aging, myelodysplastic syndrome (most common familial IPF association with telomerase mutations)
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Chest Imaging:
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CXR – could find peripheral reticular opacities
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HRCT protocol is used for diagnosis: evaluates the lung parenchyma while pt is supine, prone, with inspiratory and expiratory cuts
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There are two morphologic features on HRCT
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Usual Interstitial Pneumonia (UIP): basilar predominant fibrosis, honey combing, and traction bronchiectasis. Minimal GGOs. Pattern seen in IPF.
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Non-Specific Interstitial Pneumonia (NSIP): Marked by subpleural sparing, increased reticular patterns, and mosaic attenuation due to air trapping. Minimal or absent honeycombing
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Labs¶
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Rule out infection: CBC, RPP, sputum Cx, Histo antigen, Blasto antigen, Aspergillus galactomannan, 1,3-β-D-Glucan, sputum GMS, consider NTM, HIV
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Rheumatologic workup: ANA w/ reflex ENA, ESR, CRP, CK, aldolase, consider full myositis panel, RF, anti-CCP
Bronchoscopy¶
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BAL is not diagnostic ILD (except eosinophilic PNA), may be helpful to rule out infection
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Transbronchial biopsy is the gold standard for diagnosis. Surgical lung biopsy may be helpful in cases where the clinical evaluation and imaging are not effective (uncommon)
Misc:¶
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PFTs with 6-minute walk test (prognostic value)
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TTE to evaluate for pHTN
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SLP evaluation for indolent aspiration
Management¶
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Acute flare – all non- UIP = may respond to steroids. Consult rheumatology if CTD origin for further options.
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Chronic therapy
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Consider tyrosine kinase inhibitor (nintedanib; INPULSIS trial) and antifibrotics (pirfenidone; ASCEND trial) – reduces FVC decline but no change in mortality
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There is increased mortality in IPF with azathioprine/pred/NAC (PANTHER-IPF); steroids are not indicated
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Immunosuppression for autoimmune related ILD
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Antigen avoidance for hypersensitivity pneumonitis
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Consider lung transplant evaluation for severe disease