Pulmonary pathology Flashcards
Bronchopneumonia with patchy areas of tan-yellow consolidation. Remaining lung is dark red because of marked pulmonary congestion.
What is this pathology, and what are some typical pathogens that cause it?
Bronchopneumonia. The lighter areas that appear to be raised on cut surface from the surrounding lung are the areas of consolidation of the lung. Typical bacterial organisms include: Staphylococcus aureus, Klebsiella, E. coli, Pseudomonas.
What is this pathology, and what is the typical patient who acquires this disease?
Bronchopneumonia. A bronchopneumonia is classically a “hospital acquired” pneumonia seen in persons already ill from another disease process.
Bronchopneumonia.
This is a lobar pneumonia in which consolidation of the entire left upper lobe has occurred. This pattern is much less common than the bronchopneumonia pattern. In part, this is due to the fact that most lobar pneumonias are due to Streptococcus pneumoniae (pneumococcus) and for decades, these have responded well to penicillin therapy so that advanced, severe cases are not seen as frequently. However, pneumoccoci, like most other bacteria, are developing more resistance to antibiotics. Severe pneumococcal pneumonia still occurs, even in young to middle aged persons (not just the very young and the very old) and has a mortality rate of 20%!
A closer view of the lobar pneumonia demonstrates the distinct difference between the upper lobe and the consolidated lower lobe. Radiographically, areas of consolidation appear as infiltrates.
Empyema is a collection of pus in the pleural space. The pleural surface left demonstrates thick yellow-tan purulent exudate and the pleural cavity is filled with purulent exudate. This is an empyema. Pneumonia may be complicated by a pleuritis. Initially, there may just be an effusion into the pleural space. There may also be a fibrinous pleuritis. However, bacterial infections of lung can spread to the pleura to produce a purulent pleuritis.
What is this pathology, what causes it, and name one pathogen that causes it most commonly.
Lung abscesses, one in the upper lobe and one in the lower lobe of this left lung. There are adjacent areas of tan consolidation with bronchopneumonia. An abscess is a complication of severe pneumonia, most typically from virulent organisms such as Staphylococcus aureus. Abscesses are often complications of aspiration, where they appear more frequently in the right posterior lung.
At the left the alveoli are filled with a neutrophilic exudate that corresponds to the areas of consolidation seen grossly with the bronchopneumonia. This contrasts with the aerated lung on the right of this photomicrograph.
At higher magnification can be seen a patchy area of alveoli that are filled with inflammatory cells. The alveolar structure is still maintained, which is why a pneumonia often resolves with minimal residual destruction or damage to the lung.
At high magnification, the alveolar exudate of mainly neutrophils is seen. The surrounding alveolar walls have capillaries that are dilated and filled with RBC’s. Such an exudative process is typical for bacterial infection. This exudate gives rise to the productive cough of purulent yellow sputum seen with bacterial pneumonias.
More virulent bacteria and/or more severe pneumonias can be associated with destruction of lung tissue and hemorrhage. Here, alveolar walls are no longer visible because there is early abscess formation. There is also hemorrhage.
At higher magnification, early abscessing pneumonia is shown. Alveolar walls are not clearly seen, only sheets of neutrophils.
Aspiration pneumonia. This more focal abscess containing a neutrophilic exudate as well as dark blue bacterial colonies suggests aspiration or hematogenous spread of infection to the lung. Aspirated material from the oral-pharyngeal region contains bacterial flora. Hematogenous spread of infection to lungs could occur from septicemia or from infective endocarditis involving the right side of the heart.
Aspiration pneumonia. There is a localized foreign body giant cell (multinucleated cells on left, formed from fused histocytes) response to the aspirated material (right) seen here at high magnification. Aspirated material may also produce inflammation from chemical irritation, as with gastric contents.
