Inflammation Case Studies


CASE 4: Acute pneumonia


Clinical History:

An 83-year-old woman experienced cough, fever, and shaking chills for two days prior to admission. Physical examination revealed rales in the right lung base. She was coughing up a small amount of yellowish sputum. Chest x-ray initially showed a right lower lobe infiltrate, but several days later showed infiltrates throughout the right lung. Sputum culture grew Streptococcus pneumoniae. (image 4.1 demonstrates the gross appearance of the lung, and images 4.2 through 4.4 illustrate the microscopic findings).
  1. How would you describe the gross appearance of the lung?

    2. Patchy areas of yellowish tan consolidation are present, consistent with bacterial pneumonia.

  2. What do you see in the alveolar spaces in the lung?

    3. The alveolar spaces are filled with an exudate containing numerous neutrophils along with some macrophages and pink strands of fibrin generated by the coagulation system initiated by the inflammatory process. Alveolar capillaries are congested and filled with RBC's.

  3. How would this differ from a causative agent such as influenza virus?

    4. Inflammation caused by viruses is typically interstitial and mostly composed of mononuclear cells. However, the damage done by viral inflammation in the lung can predispose to bacterial infection.

  4. What chemical mediators are responsible for fever?

    5. Interleukin-1 (IL-1) and tumor necrosis factor (TNF) are the mediators most associated with development of fever.

  5. What is the diagnosis?

    6. This is an acute pneumonia. Streptococcus pneumoniae is a bacterial organism that typically produces a lobar pattern of pulmonary involvement. A more virulent organism (usually seen in hospitalized patients) is Staphylococcus aureus which can cause abscess formation.