Interstitial Lung Disease

  1. Definition: Heterogeneous group of diseases which affect the lung parenchyma (all lung tissues- bronchioles, bronchi, alveoli, interstitium).
  2. Characterisedby: chronic inflammation and remodelling +/- progressive interstitial fibrosis, hyperplasia of type II epithelial cells and pneumocytes.
  3. Radiological changes keywords: ground-glass opacities/honeycombing/ streaky fibrosis, reticulo-nodular shadowing.
  4. Classification: “Do you know what the cause is?”
  • “NO”- IPF aka Cryptogenic Fibrosing Alveolitis
  • “YES- SPECIFIC” :

(a) Drugs: Nitrofurantoin, Cytotoxics: Bleomycin/ Methotrexate, Sulfasalazine, Amiodarone (Refer:

(b) Infection: “TB is CRAP”- TB, Chlamydia Trachomatis, Respiratory Syncytial Virus, Atypical Pneumonia, Pneuocystii Pneumonia)

(c) “A-CHOO!!!!”- Dusts!

Organic: Spores/proteins from birds/ malts/ mushrooms/ hot tubs/ cheese!

Industrial: Coal, Asbestos, Berryllium, Silicon

  • “YES- SYSTEMIC”: RA, Sarcoidosis, UC, SLE, Sjogren’s, Renal Tubular Acidosis etc.
  1. Signs & Symptoms:
  • Progressive deterioration
  • Dry, persistent cough
  • Reduced exercise tolerance
  • (effort dyspnoea)
  • Drug history
  • Occupational history
  • Pets and hobbies
  • An abnormal CXR
  • Signs/symptoms of CT disease
  1. Findings O/E:
  • Dyspnoeic
  • Clubbing/ Cyanosis
  • Reduced expansion
  • Deviated trachea- towards pathological side
  • Dull percussion (localized)
  • Fine end-inspiratory crackles
  • Bronchial breathing (localized); Vesicular breathing (diffuse)

7. Investigations: BTS Guidelines very useful for all reps conditions!

  • Urine dip (e.g. haematuria in RTA)
  • FBC, U&E, LFTs
  • Spirometry ( RESTRICTIVE DEFECT) and gas transfer (TLCO; <40% =advanced disease- consider transplant!)
  • CXR and HRCT (for those with normal CXR, thin slices 1-2mm at intervals 10-20mm)
  • BAL (inflammatory cells/granulomas) and lung biopsy (before treatment- cancers)
  • Other tests: sputum culture, ABG , CRP/ESR, BNP, RF/ anti-CCP, ANA, ANCA, Serum ACE; Echocardiogram (RVF/Cardiomyopathy)
  1. General management principles:
  • Acute:ABCD and ? ABx if infective exacerbation
  • Conservative: Lifestyle – exercise, weight loss, pulmonary rehab + Smoking cessation: up to 10-fold increased risk of developing lung cancer
  • LTOT: (BTS indications)

(a)PaO2 is ≤7.3 kPa (55 mmHg + clinical stability. Clinical stability= absence of exacerbation of chronic lung disease for the previous five weeks.)

(b)PaO2 between 7.3 kPa and 8 kPa, together with : Secondary polycythaemia / Clinical and or echocardiographic evidence of pulmonary hypertension

(c)PaO2> 8kPa : NIL LTOT

  1. IPF: Dx of exclusion, unknown aetiology
  2. Pathogenesis: Soluble immune complexes + sensitized T lymphocytes activate macrophages + alveoli epithelial cells growth factor initiations Type 1+3 collagen deposits
  3. Radiologically: bi-basal, peripheral reticulo-nodular opacities, traction bronchiectasis and honeycombing. (Rarely GGO)
  4. HRCT: Usual Interstitial Pneumonia =subpleural basal predominance,reticular pattern, honeycombing, absence of micronodules/cysts
  5. Histology- (a) Cell infiltration: T lymphocytes + plasma cellsFibrosis + (b) Alveolitis: Increased macrophages/ Type IIPneumocytes in alveolar space
  6. Rx: Supportive; Transplant; N-acetylcysteine+ Azathioprine + Prednisolone (small evidence of success)
  7. Prognosis: Poor, 2-5yrs, complicated by bronchogenic Ca, death by T1RF
  8. Occupational Lung Disease: HP aka EAA
  • dust particles reach the terminal airways and epithelial lining inflammatory reaction scarring + fibrosis
  • Type 3 Hypersensitivity Reaction (Neutrophils+Complement Pathway)
  • Acute: alveolar infiltration with inflammatory cells; Chronic: granuloma+obliterative bronchiolitis
  • Symptoms start 4-6 hours after exposure to the antigen (may resolve and demonstrate cyclical pattern according to daily routine)
  • Measure serum preciptins: IgG
  • Histology: lymphocytes and non-caseating granulomas, bronchocentric
  • Radiology- upper zone fluffy nodular shadows, mid-zone mottling/consolidation, rarely hilar lymphadenopathy, honeycombing
  • Flu-like Sx: fevers, rigors, myalgia, weight loss, (later) cor pulmonale symptoms + T1RF
  • Rx: it is reversible if diagnosed early: Acute: Remove allergen/ PPE, O2 therapy, oral prednisolone (40mg/24hr- then reduce); Chronic: Avoid exposure (face masks), long term steroids (high dose Prednisolone 30-60mg OD
  • Industrial Dusts: CABS; Eligible for compensation through Industrial Injuries Act 1965
  • NB: Malignant Mesothelioma with Asbestosis/ Asbestos Exposure
  1. Sarcoidosis:
  • Multi-system granulomatous disease of unknown aetiology
  • Age 20-40yo, Afro-Caribbeans
  • Erythema nodosum/ uveitis/ keratoconjunctivitis sicca/ hepatosplenomegaly/ dysrhythmias/ CCF/ arthralgia/ polyneuropathy/ meningoencephalitis
  • Rx: acute NSAIDs, can recover spontaneously
  • Steroids if symptomatic or static parenchymal disease, uveitis, hypercalcaemia, neurological or cardiac involvement
  • Prognosis: 60% thoracic involvement have spontaneous resolution, 20% respond to steroids
  1. Further reading:
  • BTS:
  • Kumar and Clark page 935-947
  • Pnumotox:
  • OHCM (Pages depending on edition)
  • Radiology Masterclass: (Revision on radiology images)

GOOD LUCK!

Prepared by Rachel Cheong & Grace Pink