Etiologies of ILD

Sarcoidosis (Lancet 2003:361:1111;/AMA 2003:289 330)

• Prevalence: African Americans, northern Europeans, and females: onset in decade

• Pathophysiology, depression of cellular immune system peripherally, activation centrally

• Clinical manifestations: asx hilar LAN i ILD or fever, malaise, dyspnea, arthralgias, rash

Stages: I = bilateral hilar LAN; II LAN + ILD; III ILD only; IV diffuse fibrosis Extrathoracic: erythema nodosum and/or skin plaques ( 25%); uveitis (-25%); hepatomegaly • granulomatous hepatitis ( 25%); BM & splenic granulomas ( 50%); CNS/ peripheral neuropathy ( 5%); cardiac conduction dis. (—5%); T parotid (<10%) Lofgren s syndrome: erythema nodosum * hilar adenopathy * arthritis Ddx erythema nodosum: idiopathic (34%). infection (33%. Strep. TB). sarcoid (22%). drugs (OCR PCNs). vasculitis (Behcet's). IBD. lymphoma (Antuitn Rheum 2000*3.584)

• Diagnostic studies: LN bx -» noncaseating granulomas * multinucleated giant cells t ACE (Se 60%. 90% w/ active dis.. Sp 80%, false 0 in granulomatous diseases) hypercalciuria and hypercalcemia (10%. due to vitamin D hydroxylation by M«); lymphopenia, eosinophilia. t ESR. polyclonal t IgG. cutaneous anergy (70%)

• Treatment: steroids if sx. t Ca, or extrathoracic organ dysfxn, but controversial

(JAMA 2002:287:1301; EfiJ 2006:28:627); anti-TNF. MTX.AZA. cyclophosphamide also used

• Prognosis: some spontaneously remit (60-80% of stage 1,50-60% stage II, 30% stage

III). 40% improve on Rx. 20% go on to irreversible lung injury

Iatrogenic

• Chemo: bleomycin (triggered by hyperoxia), busulfan, cyclophosphamide. MTX. nitrosourea

• Other drugs: nitrofurantoin, sulfonamides, thiazides, amiodarone. INH. hydralazine, gold amio (10%; dose & duration depend.): chronic interstitial pneumonia -» ARDS; bx -» vacuolized M<j> w/ lamellar inclusions on EM; Rx: d/c amio, steroids

• Radiation (-» BOOP): oftentimes with sharply linear, non-anatomic boundaries

Idiopathic interstitial pneumonias (MPs) (ajrccm 2005:172:268)

• Definition: ILD of unknown cause: dx by clinical, radiographic and histologic features

• Idiopathic pulmonary fibrosis (IPF usual interstitial pneumonia (UIP); (ajrccm

2000:161:646): sx >12 mos; HRCT: peripheral, subpleural, basal reticular opacities, traction bronchiectasis & honeycombing. Rx: ? IFN-7 i mort. (nejm 2004:350 i2S:Oi«t 2005:128.203) NAC 600 tid slowed 1 lung fxn (nejm 2005:353.2229); 5-y mort. 80%

• Acute interstitial pneumonia (AIP. "Hamman-Rich syndrome"):sx 1-2 wks; HRCT:

ground glass w/ lobar sparing; Rx: ? steroids: 6-month mort. 60%

• Cryptogenic organizing pneumonia (COP, also called bronchiolitis obliterans w/ organizing pneumonia. BOOP. if cause known): prolif. granulation tissue in small bronchioles and inflammation of surrounding alveoli. Causes of BOOP: post-infxn. drugs (amiodarone. bleomycin), rheum, diseases. post-HSCT or XRT (Archwt 2001:161:158); sx <3 mos; HRCT: subpleural. peribronchial nodules or patchy consolidation; Rx: steroids; 5-y mort. <5%

• Desquamative interstitial pneumonia (DIP) & respiratory bronchiolitis-associated ILD

(RBILD): M<t» in alveoli in smokers age 30-50; RBILD milder form; sx wks-mos; HRCT: DIP w/ diffuse ground glass mid/lower lobes; RBILD w/ nodules, bronchial thickening, patchy ground glass; Rx: quit smoking, ? steroids; death rare

• Nonspecific interstitial pneumonia (NSIP): histologic mimic of CTDs & hypersens.;

cellular & fibrotic types; sx for mos-y, HRCT: symmetric basal subpleural homogenous ground glass or consolidation; Rx: steroids; 5-y mort. 10% (fibrotic t)

• Lymphocytic interstitial pneumonia (LIP): polyclonal B-cell infiltration of lung;sx >1 yr;

HRCT: diffuse ground glass, nodules, thin-walled cysts; Rx: steroids; prog unknown Environmental & occupational exposures (nejm 2000,341406)

• Pneumoconioses (inorganic dusts)

Coal worker's: upper lobe coal macules; may progress to massive fibrosis Silicosis: upper lobe opacities ± "eggshell calcification" of lymph nodes; t risk of TB Asbestosis: lower lobe fibrosis, calcified pleural plaques; T risk of mesothelioma Berylliosis: multisystemic granulomatous disease that mimics sarcoidosis

• Hypersensitivity pneumonitides (organic dusts): loose, noncaseating granulomas

Antigens:"farmers lung" (spores of thermophilic actinomyces);"pigeon fanciers lung" (proteins from feathers and excreta of birds);"humidifier lung" (thermophilic bacteria) Pathophysiology: immunologic rxn; either acute (6 h after exposure) or chronic

Collagen vascular diseases (E/y 2001:18:69*nqm 2006:3551655)

• Rheumatologic disease

Scleroderma: fibrosis in -67%; PHT seen in 10% of CREST Pts PM-DM: ILD & weakness of respiratory muscles; MCTD: PHT & fibrosis SLE & RA: pleuritis and pleural effusions more often than ILD

• Vasculitis (can p/w diffuse alveolar hemorrhage)

Wegener's granulomatosis (® c-ANCA) w/ necrotizing granulomas Churg-Strauss syndrome (0 c- or p-ANCA) w/ eosinophilia & necrotizing granulomas Microscopic polyangiitis (® p-ANCA) w/o granulomas Diffuse alveolar hemorrhage (DAH)

• CHF-like CXR appearance, but does not resolve w/ diuresis; ± hemoptysis, i Hct, T DlCO

• Goodpasture's syndrome DAH < RPGN; typically in smokers; © anti-GBM in 90%

• Idiopathic pulmonary hemosiderosis (IPH): a rare disease and dx of exclusion

• Other: ANCA $ vasculitis. SLE. PM. APLA. crack cocaine. HSCT. XRT

Pulmonary infiltrates w/ eosinophilia (PIE) - eos on BAL : periph. blood

• Allergic bronchopulmonary aspergillosis (ABPA): allergic reaction to Aspergillus

Criteria: asthma, pulm infiltrates (transient or fixed), skin rxn & serum precipitins to Aspergillus, t IgE to Aspergillus & total ( -1000),' eos. central bronchiectasis Rx: steroids • itraconazole for refractory cases (nejm 2000:342:756)

• Loffler s syndrome: transient pulmonary infiltrates f cough, fever, dyspnea, eos due to parasites (Ascariasis. hookworm. Slrongyloidcs) or drugs (nitrofurantoin, crack)

• Acute eosinophilic pneumonia (AEP): acute hypoxic febrile illness; Rx: steroids

• Chronic eosinophilic pneumonia (CEP):"photonegative" of CHF. typically in women

• Other: Churg-Strauss syndrome; hypereosinophilic syndrome Miscellaenous

• Pulmonary alveolar proteinosis (PAP): accumulation of surfactant-like phospholipids; male smokers; cough w/ white & gummy sputum; BAL milky fluid (nejm 2003:349:2527)

• Langerhans cell granulomatosis (LCG): affects young male smokers; cysts; PTX in -25%

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