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Interstitial Lung Disease

Pakinam Mekki


Background

  • 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

  • ILD is divided into primary (idiopathic) causes and secondary causes

  • Idiopathic: idiopathic pulmonary fibrosis, eosinophilic pneumonia, idiopathic NSIP, organizing pneumonia, acute interstitial pneumonia, etc

  • Secondary

    • Systemic:

      • Connective tissue disease: RA, Sjogrens, dermatomyositis, polymyositis SLE, MCTD, scleroderma

      • Granulomatous disease: sarcoidosis, TB

      • Vasculitis: granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, amyloidosis, lymphangioleiomyomatosis

    • Exposure

      • Pneumoconiosis (inorganic) – exposure to coal mines, silica, asbestos, organic solvents, heavy metals, solder, hair dressing chemicals

      • Hypersensitivity pneumonitis (organic)- farm exposures, chicken coops, pesticide, stored grains, mold (ex: water damage in home, hot tubs)

      • Iatrogenic – amiodarone, immunotherapies, TKI, TNF-a inhibitors, nitrofurantoin, radiation

Evaluation

  • Dry cough is the most common symptom of ILD. Productive coughs are uncharacteristic

  • History:

    • Duration, timing, severity of respiratory symptoms

    • Exposures – pets, occupation, residence, smoking, drugs, travel, hobbies, dust, hay, grass,

    • Screen for autoimmune symptoms (arthritis, myalgia, rash, Raynaud’s phenomenon

    • Screen for vasculitis symptoms: hematuria, hemoptysis, mononeuritis multiplex

    • Medication history

    • Family history – premature aging, myelodysplastic syndrome (most common familial IPF association with telomerase mutations)

  • Chest Imaging:

    • CXR – could find peripheral reticular opacities

    • HRCT protocol is used for diagnosis: evaluates the lung parenchyma while pt is supine, prone, with inspiratory and expiratory cuts

    • There are two morphologic features on HRCT

      • Usual Interstitial Pneumonia (UIP): basilar predominant fibrosis, honey combing, and traction bronchiectasis. Minimal GGOs. Pattern seen in IPF.

      • Non-Specific Interstitial Pneumonia (NSIP): Marked by subpleural sparing, increased reticular patterns, and mosaic attenuation due to air trapping. Minimal or absent honeycombing

Labs

  • Rule out infection: CBC, RVP, sputum Cx, Histo antigen, Blasto antigen, Aspergillus galactomannan, 1,3-β-D-Glucan, sputum GMS, consider NTM, HIV

  • Rheumatologic workup: ANA w/ reflex ENA, ESR, CRP, CK, aldolase, consider full myositis panel, RF, anti-CCP

Bronchoscopy

  • BAL is not diagnostic ILD (except eosinophilic PNA), may be helpful to rule out infection

  • 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:

  • PFTs with 6-minute walk test (prognostic value)

  • TTE to evaluate for pHTN

  • SLP evaluation for indolent aspiration

Management

  • Acute flare – all non- UIP = may respond to steroids. Consult rheumatology if CTD origin for further options.

  • Chronic therapy

    • Consider tyrosine kinase inhibitor (nintedanib; INPULSIS trial) and antifibrotics (pirfenidone; ASCEND trial) – reduces FVC decline but no change in mortality

    • There is increased mortality in IPF with azathioprine/pred/NAC (PANTHER-IPF); steroids are not indicated

    • Immunosuppression for autoimmune related ILD

    • Antigen avoidance for hypersensitivity pneumonitis

  • Consider lung transplant evaluation for severe disease


Last update: 2022-06-26 16:13:51