Explain the pathogenesis of coal-workers' lung disease.
Particles are taken up by macrophages in alveoli. Particles are deposited in centrolobular zones and may be associated with fibrosis or centroacinar emphysema.
What is silicosis, and how does it present pathologically?
Inhalation of silica (sand-blasting, mining, stone cutting)
causes fibronodular lesions in the lung parenchyma. Particles taken up by macrophages, which release silica crystals and stimulate fibroblasts to produce collagen
**TB is a common complycation b/c silica-laden macrophages cannot effectively combat mycobacterial infections
Which lung diseases are related to exposure to asbestos?
- pulmonary fibrosis
- pleural fibrosis and pleural plaques
- lung cancer
- mesothelioma
Explain the pathogenesis of dyspnea caused by various mechanisms.
large airway obstruction . . . laryngospasm
small airway obstruction . . . bronciolitis, asthma
intra-alveolar obstruction . . . pneumonia, edema
alveolar septal lesions
destruction . . . emphysema
increase in thickness . . . intersitital fibrosis
collapse . . . atelectasis
CNS causes . . . apoplexy of respiratory centers
Compare the pathologic findings in wet drowning and dry drowning.
wet drowning: water prevents entry of air, death occurs within minutes
dry drowning: reflex laryngospasm closes glottis and prevents air/fluid
List four main pathogenetic mechanisms of ventilatory failure and explain how they affect respiration.
-
Neural control
depends on CO2 content
e.g. apoplexy
-
Respiratory muscles
striated muscles dependent on cranial/spinal nerves
e.g. polio, tetanus, MG, MD
-
Chest wall
can restrict expansion
e.g. kyphoscoliosis
-
Airways
alveolar hypoxia
cystic fibrosis, laryngospasm
depends on CO2 content
e.g. apoplexy
striated muscles dependent on cranial/spinal nerves
e.g. polio, tetanus, MG, MD
can restrict expansion
e.g. kyphoscoliosis
alveolar hypoxia
cystic fibrosis, laryngospasm
List common causes of acute respiratory distress syndrome.
Shock
- trauma
- burns
- acute cardiac failure
Pneumonia
- bacterial
- viral
Toxic lung injury
- toxic fumes
- cytotoxic drugs
- bacterial endotoxins
Aspiration of fluids
Describe the pathology of acute respiratory distress syndrome and explain its pathogenesis.
alveolar injury = initiating event in viral pneumonia or fumes
endothelial injury = initiating event in sepsis
regardless of initial injury, lesions are comprised of hyaline membranes, ruptured alveolar walls, and intra-alveolar edema
see pg. 185 in book
What are the possible outcomes of acute respiratory distress syndrome?
1/3 die within days
+
1/3 die of pneumonia and heart failure within weeks
+
1/3 recover
What is atelectasis, and what are its possible causes?
atelectasis is the incomplete expansion or collapse of alveoli.
- deficiency of surfactant
- compression of the lungs from outside
- resorption of air distal to bronchial obstruction
What are the most important neoplasms of the respiratory tract?
lung cancer + carcinoma of the larynx
Correlate the pathology of carcinomas of the larynx with clinical findings and prognosis of the disease.
* all are squamous cell
- linked with smoking and chronic alcohol
- rare <40 yrs
- can originate in any part of the larynx
- present as nodules and ulcerations of the mucosa
patients present relatively early with hoarseness, stridor. 75% 5yr survival.
How common is lung cancer?
Most common malignant disease of internal organs and leading cause of cancer death in the US
How is tobacco smoking related to lung carcinoma?
90% of patients with lung cancer are smokers!
Tobacco smoke has polycyclic hydrocarbons that initiate and promote malignant transformation of cells. Also contains procarcinogens.
Explain the histogenesis of various histologic types of lung carcinoma.
Columnar epithelium undergoes squamous metaplasia, which can progress to carcinoma in situ and invasive squamous cell carcinoma.
adenocarcinomas = mucous/ciliated cells
small-cell = neuroendocrine cells
large-cell = anaplastic stem cells
Compare hilar (central) and peripheral lung carcinoma.
Central = squamous, large-cell, small-cell
peripheral = adenocarcinomas
Where do lung carcinomas metastasize?
- Liver
- Brain
- Bone
- Adrenals
What are the clinical signs of lung cancer?
- bronchial irritation/obstruction
wheezing, dyspnea, hemoptysis
- local extension into the mediastinum or pleural cavity
atelectasis, dysphagia
- distant mets
HSM, neurologic symptoms, Addisons
- systemic effects
weight loss, anorexia, malaise
What are the common paraneoplastic syndromes caused by lung carcinoma?
PTH >> hypercalcemia
ACTH >> Cushing's
ADH >> hyponatremia
Compare pneumothorax and hydrothorax.
pneumothorax = air in the pleural cavity
hydrothorax = fluid in pleural cavity
Explain the pathogenesis of pleuritis.
Hallmark = exudate
bacterial pneumo >> fibrinous/purulent
viral >> serous
TB >> serous or fibrinous, NO PMNs
heart failure/edema >> transudate
What is mesothelioma?
rare malignant tumor of the pleura
*often r/t asbestos
What makes interstitial pneumonia unique?
Interstitial . . . inflammation affects the alveolar septa and does not result in exudation of PMNs into the alveolar lumen. Also viruses that cause interstitial pneumonia attach to respiratory epithelial cells >> cell necrosis = "reticular pattern" on x-ray
How is pneumonia diagnosed?
- x-ray
- sputum studies
- peripheral blood studies
What are some unique features of TB?
- acid-fast bacillus (Ziehl-Neelsen)
- TB does NOT attract PMNs, but forms granulomas
- Ghon complex = parenchymal focus and hilar lymph node lesion
- Ghon complex = central caseous necrosis surrounded by epithelioid cells, multinucleated giant cells, lymphocytes
What is the defnition of chronic bronchitis?
excessive production of tracheobronchial mucus causing cough and expectoration for at least 3 months during 2 consecutive years.
