12/7 Diffuse Infiltrative Disease - Scardella Flashcards
diffuse parenchymal lung diseases (DPLD)
heterogeneous group of noninfectious nonmalignant processes of lower respiratory tract that commonly result in:
- restrictive ventilatory impairment
- diffuse interstitial infiltrates
often progressive and/or fatal
5 types
clinical presentation of DLPD
most common sx: dyspnea on exertion, cough, abnormal CXR, physiological impairment
often assoc with another disease (esp CTD)
often positive “exposure” hx
functional and radiographic abnormalities
- reduced TLC, VC, FEV1, RV → reduced lung compliance
- airway resistance is NORMAL (normal FEV1/FVC)
- gas exchange ABNORMAL (decr DL CO, PaO2)
physical exam findings: DPLD
- crackles
- common: IPF (interstitial pulm fibrosis)
- rare: granulomatous lung disease
- skin changes
- joint deformities
- clubbing
- signs of cor pulmonale
major histopathological patterns of DPLD
- granulomatous process
- accumulation of T lymophocytes, macrophages, epithelioid cells organized into discrete structures (granulomas)
- derangement of normal tissue architecture
- interstitial inflammation and fibrosis
granulomatous processes
- sarcoidosis
- organic dusts
* hypersensitivity pneumonitis - inorganic dusts
- silica
- beryllium
- granulomatous vasculitis
- Wegener’s granulomatosis
- Churg-Strauss
sarcoidosis
etiology
features
at risk pops
extrapulmonary sarcoidosis
radiographic manifestation
dx and prognosis
treatment
unknown etiology (interplay of antigen, HLA class II molecules, T cell receptors)
non-caseating granulomas → organ dysfunction
at risk pops:
- Scandinavian pops, blacks 10x
- most common in 30s, 40s
extrapulmonary sarcoidosis
- ophthalmic granulomatosis
- peripheral adenopathy
- curaneous rash
- CNS involvement
- cardiac arrhythmias
- hepatitis
- hypercalcemia
radiographic manifestations
- bilateral hilar adenopathy (most common)
- types: diffuse reticular, reticulonodular, nodular
- multiple large nodules
- diffuse “alveolar” hemorrhage
- normal also poss
diagnosis and prognosis
- diagnosis of exclusion (no specific test that can ID it; have to rule everythign else out)
- most common outcome: spontaneous resolution without sequelae
- 10% severe fibrosis, permanent loss of lung fx
- 5% death
treatment
- treat for symptoms, NOT for anyone else
hypersensitivity pneumonitis
basics
3 forms
CXR findings
major predictor
aka extrinsic allergic alveolitis
- caused by repeated inhalation of finely dispersed antigens
- “antigens” = wide variety of organic particles (sources incl mammal/avian proteins, thermophilic bacteria, fungi, etc)
3 forms
-
acute: intermittent and intense exposure
- sx 4-8hr post exposure
- fever, chills, malaise, dyspnea, cough
- CXR: diffuse ground glass appearance or air-space consolidation
-
subacute: continual, low-level exposure
- dyspnea and fatigue
- unrecog’d/untreated → chronic
- CXR: fine nodular or reticulonodular pattern
-
chronic
- later form of subacute
- irreversible lung changes
- CXR: predominantly reticular pattern
- distribution involves mainly upper 2/3 of lungs
- in all forms: tachypnea and crackles!
big time predictor: exposure to known offending antigen (OR 38.8)
hypersensitivity pneumonitis
treatment
early dx and avoidance of antigen exposure
dust masks, ventilation, industrial hygiene
corticosteroids in acute disease (but long term efficacy not established)
silicosis
- most common pneunoconiosis worldwide
- attributable to inhalation of silicon dioxide (silica)
- develops slowly: 10-30yrs req from exposure to recog of disease
- two forms: simple and complicated
1. simple silicosis
- describes mildest, earliest form of disease
- asymptomatic or chronic cough
- CXR: upper zone distribution of small rounded opacities less than 10mm in diameter; “eggshell calcifications” around lymph nodes
- sx don’t correlate with CXR findings
- PFTs initially normal, but TLC decreases as number/density of opacities rises
- TB incidence incr by 2-30x
2. complicated silicosis (aka progressive massive fibrosis)
- occurs when smaller opacities coalesce
- sx range from minimal to severe dyspnea
- CXR: confluent nodules > 10mm
- nodules become confluent peripherally and migrate centrally
- PFTs: progressive deterioration
- progression in absence of further exposure
chronic beryllium disease
cant distinguish from sarcoidosis!
- non-caseating granulomas in lung parenchyma and hilar lymph nodes
- systemic disease with granulomas in all organs possible
- PFT and CXR findings: same as sarcoidosis
interstitial inflammation and fibrosis
chronic inflammatory process composed of AMs, fewer lymphocytes, PMNs, eosiophils, mast cells
- injury to alveolar walls with changes in epithelium
- thickening of alveolar walls with fibrosis
marked derangement of alveolar structures with loss of functioning alveolar-capillary units
causes:
- drugs (ex. chemo), radiation, inorganic dusts (asbestos)
- chemotx: bleomycin, cylophosphamide
- CV: amiodarone
- antimicrobial: nitorfurantoin
- collagen vascular diseases, pulmo hemorrhage syndromes, lymphocytic infiltrative disorders, eosinophilic pneumonias, idiopathic interstitial pneumonias, inherited diseases (tuberous sclerosis)
asbestos & asbestosis
once upon a time, in: cement products, insulation/fireproofing, reinforced plastic/rubber pdts, textiles, paper pdts, filters
asbestosis : pulmonary parenchymal fibrosis
- prevalence depends on duration and intensity of exposure
- low level exposure? latency between exposure and disease more likely
- radiologic disease can be static or progress (progression related to cumulative dose)
- sx: dyspnea on exertion, basal crackles, clubbing
- CXR: lower lobe linear opacities
- PFTs: restrictive pattern (decr TLC, VC) with decr in diffusing capacity
other complications
- pleural disease: plaques & fibrosis
- lung cancer (5x vs 100x in smokers)
- benign asbestox pleural effusion
- malignant mesothelioma (exposure in 50%, latent pd of 20-40yr)
idiopathic interstitial pneumonias
UIP
1. usual interstitial pneumonia
- most common (50-60%), onset in 60s, v high mortality rate (68%)
- repeated cycels of epithelial activation/injury by an unidentified agent → abnormal epithelial repair at site of injury
- leads to excessive fibroblastic proliferation → characteristic fibroblastic foci seen on lung biopsy
- “temporal heterogeneity” : see areas of both early injury/repair AND late collagen deposition
acute exacerbations of IPF (idiopathic pulmonary fibrosis)
acute deterioration in sx and gas exchange secondary to infection, PE, pneumothorax, HF
may require noninvasive support or mech ventilation
- if mech ventilation req, associated with poor prognosis
tx: empiric antibiotics and high dose prednisone
CXR key for IPF: honeycombing
IIP signs and sx
