USMLE Respiratory - Pathology
A cute respiratory distress syndrome...
1) What is pathophysiology?
2) What are the causes?
3) How is the diagnosis made?
4) What are the consequences?
5) What is management? - ANS-1) Pathophysiology: Alveolar insult =
pro-inflammatory cytokines released = neutrophil recruitment + release of toxins.
Formation of intra-alveolar hyaline membrane (arrows in A) and noncardiogenic
pulmonary oedema
2) Causes: Sepsis (common), aspiration, pneumonia, trauma, pancreatitis
3) Diagnosis: Diagnosis of exclusion with the following criteria (ARDS)
A - abnormal chest X-ray (bilateral lung opacities) - SEE B
R - respiratory failure within 1 week of insult
D - Decreased PaO2/FiO2
S - symptoms of respiratory failure are not due to HF/fluid overload
3) Consequences: Impaired gas exchange, ↓ lung compliance, pulmonary
hypertension
4) Management: Treat underlying cause. Mechanical ventilation: ↓ tidal volumes, ↑
PEEP
\Adenocarcinoma of the lung
1) What is the location?
2) What are the characteristics?
3) What is the histology? - ANS-Non-small cell
1. Location: Peripheral
2. Characteristics: Most common primary lung cancer. women. non-smokers.
Activating mutations include KRAS, EGFR, and ALK. Associated with hypertrophic
osteoarthropathy (clubbing)
3. Histology: Glandular pattern on histology, often stains mucin +ve (see B).
Bronchioalveolar subtype: grows along alveolar septa.
\Atelectasis (bronchial obstruction)
, 1) Are breath sounds increased, decreased or unchaged?
2) What is the percussion like?
3) What is the tactile vocal fremitus like?
4) Is there tracheal deviation? - ANS-1) Breath sounds: ↓
2) Percussion: Dull
3) Fremitus: ↓
4) Tracheal deviation: Toward side of lesion
\Bronchial carcinoid tumour
1) What is the location?
2) What are the characteristics?
3) What is the histology? - ANS-Non small cell
1. Location: Central or peripheral
2. Characteristics: Excellent prognosis; metastasis rare. Symptoms due to mass
effect or carcinoid syndrome.
3. Histology: Nests of neuroendocrine cells; chromogranin A +ve
\Bronchopneumonia
1) What are the typical organisms that cause this pneumonia?
2) What are the characteristics of this pneumonia? - ANS-1) Typical organisms: S.
pneumonia, S. aureus, H. influenzae, Klebsiella
2) Characteristics: Acute inflammatory infiltrates (see C) from bronchioles into
adjacent alveoli; patchy distribution involving more than 1 lobe (see D)
\Consolidation (lobar pneumonia, pulmonary edema)
1) Are breath sounds increased, decreased or unchaged?
2) What is the percussion like?
3) What is the tactile vocal fremitus like?
4) Is there tracheal deviation? - ANS-1) Breath sounds: Bronchial breath sounds, late
inspiratory crackles, whispering pectoriloquy
A cute respiratory distress syndrome...
1) What is pathophysiology?
2) What are the causes?
3) How is the diagnosis made?
4) What are the consequences?
5) What is management? - ANS-1) Pathophysiology: Alveolar insult =
pro-inflammatory cytokines released = neutrophil recruitment + release of toxins.
Formation of intra-alveolar hyaline membrane (arrows in A) and noncardiogenic
pulmonary oedema
2) Causes: Sepsis (common), aspiration, pneumonia, trauma, pancreatitis
3) Diagnosis: Diagnosis of exclusion with the following criteria (ARDS)
A - abnormal chest X-ray (bilateral lung opacities) - SEE B
R - respiratory failure within 1 week of insult
D - Decreased PaO2/FiO2
S - symptoms of respiratory failure are not due to HF/fluid overload
3) Consequences: Impaired gas exchange, ↓ lung compliance, pulmonary
hypertension
4) Management: Treat underlying cause. Mechanical ventilation: ↓ tidal volumes, ↑
PEEP
\Adenocarcinoma of the lung
1) What is the location?
2) What are the characteristics?
3) What is the histology? - ANS-Non-small cell
1. Location: Peripheral
2. Characteristics: Most common primary lung cancer. women. non-smokers.
Activating mutations include KRAS, EGFR, and ALK. Associated with hypertrophic
osteoarthropathy (clubbing)
3. Histology: Glandular pattern on histology, often stains mucin +ve (see B).
Bronchioalveolar subtype: grows along alveolar septa.
\Atelectasis (bronchial obstruction)
, 1) Are breath sounds increased, decreased or unchaged?
2) What is the percussion like?
3) What is the tactile vocal fremitus like?
4) Is there tracheal deviation? - ANS-1) Breath sounds: ↓
2) Percussion: Dull
3) Fremitus: ↓
4) Tracheal deviation: Toward side of lesion
\Bronchial carcinoid tumour
1) What is the location?
2) What are the characteristics?
3) What is the histology? - ANS-Non small cell
1. Location: Central or peripheral
2. Characteristics: Excellent prognosis; metastasis rare. Symptoms due to mass
effect or carcinoid syndrome.
3. Histology: Nests of neuroendocrine cells; chromogranin A +ve
\Bronchopneumonia
1) What are the typical organisms that cause this pneumonia?
2) What are the characteristics of this pneumonia? - ANS-1) Typical organisms: S.
pneumonia, S. aureus, H. influenzae, Klebsiella
2) Characteristics: Acute inflammatory infiltrates (see C) from bronchioles into
adjacent alveoli; patchy distribution involving more than 1 lobe (see D)
\Consolidation (lobar pneumonia, pulmonary edema)
1) Are breath sounds increased, decreased or unchaged?
2) What is the percussion like?
3) What is the tactile vocal fremitus like?
4) Is there tracheal deviation? - ANS-1) Breath sounds: Bronchial breath sounds, late
inspiratory crackles, whispering pectoriloquy
