Pneumoconiosis Flashcards
pneumoconiosis
the accumulation of mineral dusts inciting tissue reactions that range from minimal reversible stromal reactions to interstitial fibrosis that results in permanent scarring
silicosis
a chronic lung disease due to inhalation of crystalline silica (usually quartz)
characterized by progressive parenchymal nodules and pulmonary fibrosis
upper lobe disease
epidemiology of silicosis
most prevalent chronic occupational lung disease worldwide
risk is directly proportional to particle concentration, duration of exposure, and silica content of different rock types
Describe the common histologic features of pneumoconiosis
1) acellular hyalinized collagen
2) layered collagen
3) thick capsule
factors that increase dust deposition in the lung
exertion
younger age
close proximity to sources of dust
acute or chronic lung disorders
fast phase clearance
half-time of 3.0 +/ 1.6 hrs
mucociliary clearance
does not remove all particles deposited in the larger airways
slow phase clearance
half-time of 109 +/- 78 days
depends on lung scavenger cells (macrophages)
pathogenesis of mineral dust pulmonary toxicity
injury due to dust particle inhalation
silica engulfed by macrophages to form nodules
mitochondria - ROS/RNS and DNA damage
apoptosis and fibrotic response
scarring of the lungs
chronic silicosis
characterized by nodules that are typically located in the peribronchial regions with interstitial extension
common CXR findings of chronic silicosis
small 1-3 mm nodules
symmetrical bilateral upper lobes
calcified nodules
hilar LN with eggshell clacification
pulmonary function test for chronic silicosis
often normal early
later on will have - decreased lung volumes and diffusion capacity
eventual airway obstruction
progressive massive fibrosis
a state of silicosis where nodules expand and coalesce into large massis that can undergo necrosis
acute silicosis
characterized by diffuse fluid-filled alveolar spaces that consist of eosinophilic proteinaceous and surfactant-containing material
pathology of acute silicosis
alveolar proteinosis, poorly formed nodules, intersitial infiltrates
acute silicosis CXR
alveolar pattern - ground glass
HRCT of acute silicosis
“crazy paving” - ground glass + septal thickening
management of silicosis
avoidance
no established treatment - lung transplant
treat mycobacterial infections as silica impairs alveolar macrophages
“angel wing” appearance
the symmetrical appearance of PMF
coal worker’s pneumoconiosis
also called “black lung” or “antraco-silicosis”
due to chornic exposure to coal dust, graphite, and other forms of carbon
black nodules
carbon is less fibrogenic than quartz
pathology of coal workers’ pneumoconiosis
greater dust burden
black lung nodules (randomly arranged)
black lymph nodes
centrilobular emphysema
coal-laden alveolar macrophages
coal macules can develop into PMF if many coalesce
clinical manifestations of CWP
simple, complicated, and PMF
chronic bronchitis is a more prominent feature
an acute onset form of the disease does not occur
advanced disease can have cough, SOB, and cor pulmonale
Caplan’s Syndrome
simple CWP
most common and typically occurs after low-dose coal exposure for more than 20 years
relatively asymptomatic but can develop cough and sputum production
characteristic HRCT findings in CWP
focal emphysema
punctate opacities
subpleural nodules
PMF
cavitating masses
diffuse interstitial pulmonary fibrosis
bronchiectasis
PFT in CWP
restricted lung volumes
reduced DLCO
mixed restricted/obstructive defects
in PMF, severe mixed restriction and obstruction
not as bad as silicosis
also no cancer risk!
treatment of CWP
no established treatment
look out for complicating mycobacterial infections
asbestos-related diseases
asbestos naturally occurs in silicate fibers, ideal for construction
long latency of 15-40 years from exposure to disease
cause nonmalignant and malignant inflammatory pulmonary diseases
asbestos fiber types
serpentine and amphibole fibers
serpentine asbestos fibers
curly-stranded, curved structures
95% of insulation is chrysotile, which is a type of serpentine fiber
not as bad as amphibole fibers
amphibole asbestos fibers
straight, rod-like fibers
more harmful than serpentine fibers
amphibole hypothesis - crocidolite is especially more carcinogenic and fibrogenic
accumulate more readily in the distal lung parenchyma, not as effectively cleared
Describe the mechanism underlying free radical generation by asbestos fibers.
due to reactions occurring on surface of the mineral dusts
mitochondrial dysfunction and activation of AMs or neutrophils attempt to take upf fibers
coated with iron inside the macrophages and become ferruginous bodies
asbestos body is used to define coated fibers where the core fiber is asbestos
How does asbestos fibers proomte pulmonary toxicity?
induce AM mitochondrial H2O2 production via a Rac1-dependent mechanism
ROS production activates NALP3 inflammasomes that trigger inflammatory signaling
asbestos-induced pleural plaques
discreet collagenous material along parietal pleura of the mid-lower ribs and diaphragm
latency is greater than 20 years
prevalence varies with intensity of exposure
long fibers are retained in the parietal pleura and can block the stomata
fairly specific to asbestos exposure and rarely affects PFTs
clinical manifestations of asbestos exposure
benign asbestos pleural effusions (BAPE)
pleural plaques
rounded atelectasis
malignant mesothelioma
asbestosis
lung cancer
rounded atelectasis
a distinct form of pleural/parenchymal thickening that is characterized by its major radiographic inding, the “comet tail sign”
as pleural fibrosis progresses, it can entrap the underlying healthy lung and bronchovascular tissue
malignant mesothelioma
rare tumor caused by all forms of asbestos
no synergy with tobacco smoke
latency period of > 30 years
clinical manifestation of malignant mesothelioma
male predominant, insiduous onset
nonspecific symptoms such as fever, weight loss, night sweats, and fatigue
dyspnea, nonpleuritic chest pain, and cough may also occur
stain positive for vimentin, keratin, and calretinin
management of malignant mesothelioma
cisplatinum +/- pemextred -> 9-12 month survival
chemo, radiation, and surgery -> median survival 22 months
favorable prognostic signs of malignant mesothelioma
< 5% of total body weight loss
tumor confined to the ipsilateral pleura
epithelioid histology
good performance status
platelets < 400,000
age < 60
asbestosis
slowly progressive, diffuse pulmonary fibrotic process
present with exertional dyspnea
20 year latency period
pleural plaques present in 80-90%
similar IPF findings but with plaques
PFTs show decreased lung volumes and DLCO below normal
end-inspiratory bibasilar crackles, clubbing, and cor pulmonale
diagnosis of asbestosis
a reliable exposure history
an appropriate latency period
characteristic chest radiograph of HRCT interstitial abnormalities
reduced lung volumes and/or DLCO
end-inspiratory crackles
**unlike IPF, asbestosis is slowly progressive
What are the two most common causes of hard metal lung disease?
beryllium and cobalt
berylliosis
identical to sarcoid clinically, radiographically, and pathologically
an important early marker is the proliferation of T lymphocytes proliferating in the lung and the blood
up to 10 years of latency
PFT shows reduced volumes and DLCO
slow decline that can result in cor pulmonale
treatment for berylliosis
steroids are administered
elimination of further exposure
high correlation between berylliosis and lung cancer
cobalt-associated disease
airway obstruction that resembles occupational asthma
acute interstitial pneumonitis with features of hypersensitivity pneumonitis
chronic diffuse interstitial fibrosis
characteristic diagnostic feature is the presence of odd-appearing giant multinucleated cells
