Interstitial lung disease Flashcards
What are interstitial lung diseases of unknown etiology and of known etiology?
Unknown etiology:
- Idiopathic interstitial pneumonias
- Sarcoidosis
Known etiology:
- ILD associated with systemic rheumatic disorders (Scleroderma, RA, SLE, polymyositis)
- Environment/Occupation (Farmer’s lung, Asbestosis)
- Drugs/Treatments (Nitrofurantoin/Macrodantin, Methotrexate, Amiodarone, Chemo)
- Vasculitis (Granulomatosis with polyangiitis, Goodpasture’s syndrome)
- Inherited (Familial IPF)
- Alveolar filling disorders
What is SCHART RASIO for?
Mneumonic for Upper lobe and Lower lobe interstitial lung disease etiology
Upper Lobe ® SCHART
- S - silicosis (progressive massive fibrosis), sarcoidosis
- C - coal workers pneumoconiosis
- H - histiocytosis X
- A - ankylosing spondylitis, aspergillosis
- R - radiation
- T - TB
Lower Lobe ® RASIO
- R - rheumatoid arthritis
- A - asbestosis
- S - scleroderma
- I - idiopathic
- O - other (e.g. drugs; busulphan, bleomycin, amiodarone, methotrexate)
Pathophysiology of interstitial lung disease
• inflammatory and/or fibrosing process in the alveolar walls -> distortion and destruction of
normal alveoli and microvasculature
• typically associated with:
- lung restriction (decrease in TLC and VC)
- decreased lung compliance (increased or normal FEV1/FVC; typical of restrictive lung disease c.f. obstructive)
- impaired diffusion (decreased DLCO)
- hypoxemia due to V/Q mismatch (usually without hypercapnia until end stage)
- pulmonary HTN and cor pulmonale occur with advanced disease secondary to hypoxemia and blood vessel destruction
Px of interstitial lung disease
• SOB, especially on exertion
• nonproductive cough
• crackles (dry, fine, end-inspiratory)
• clubbing (especially in IPF and asbestosis)
• features of cor pulmonale
• note that signs and symptoms vary with underlying disease process
- e.g. sarcoidosis is seldom associated with crackles and clubbing
Ix of interstitial lung disease
• CXR/high resolution CT
- usually decreased lung volumes (c.f. COPD)
- reticular, nodular, or reticulonodular pattern (nodular 70-80%), i.e. flow rates are often normal or high when corrected for absolute lung volume
- DLCO decreased due to V/Q mismatch less surface area for gas exchange ± pulmonary vascular disease
• ABGs
- with progression of disease, hypoxemia and respiratory alkalosis may be present
• other
- bronchoscopy, bronchoalveolar lavage, lung biopsy
ESR, ANA (lupus), RF (RA), serum-precipitating antibodies to inhaled organic antigens (hypersensitivity pneumonitis), c-ANCA (GPA), anti-GBM (Goodpasture’s)
Define sarcoidosis & its characterisation
- idiopathic non-infectious granulomatous multi-system disease with lung involvement in 90%
- characterized pathologically by non-caseating granulomas
- numerous HLA antigens have been shown to play a role and familial sarcoidosis is now recognized
Who gets sarcoidosis?
- typically affects young and middle-aged patients
* higher incidence among black Americans and people at northern latitudes e.g. Scandinavia, Canada
Px of sarcoidosis
• asymptomatic, cough, dyspnea, fever, arthralgia, malaise, erythema nodosum, chest pain
• chest exam often normal
• common extrapulmonary manifestations
- cardiac (arrhythmias, sudden death)
- eye involvement (anterior or posterior uveitis)
- skin involvement (skin papules, erythema nodosum, lupus pernio)
- peripheral lymphadenopathy
- arthralgia
- hepatomegaly ± splenomegaly
• less common extra-pulmonary manifestations involve bone, CNS and kidney
Ix of sarcoidosis
- CBC (cytopenias from spleen or marrow involvement)
- serum electrolytes, creatinine, liver enzymes, calcium (hypercalcemia/hypercalciuria due to vitamin D activation by granulomas)
- hypergammaglobulinemia, occasionally RF positive
- elevated serum ACE (non-specific and non-sensitive)
- CXR: predominantly nodular opacities especially in upper lung zones ± hilar adenopathy
- PFTs: normal, obstructive pattern, restrictive pattern with normal flow rates and decreased DLCO
- ECG: to rule out conduction abnormalities
- slit-lamp eye exam: to rule out uveitis
Rx of sarcoidosis
• 85% of stage I resolve spontaneously
• 50% of stage II resolve spontaneously
• STEROIDS for symptoms, declining lung function, hypercalcemia, or involvement of eye, CNS,
kidney, or heart (not for abnormal CXR alone)
• methotrexate or other immunosuppressives occasionally used
Prognosis of sarcoidosis
• approximately 10% mortality secondary to progressive fibrosis of lung parenchyma
What are the (2) acute sarcoid syndromes?
- Lofgren’s syndrome: fever, erythema nodosum, bilateral hilar lymphadenopathy, arthralgias
- Heerfordt-Waldenstrom syndrome: fever, parotid enlargement, anterior uveitis, facial nerve palsy
