MEDizzy - A 68-year-old man has had worsening shortness of breath for

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Inflammation and Repair

A 68-year-old man has had worsening shortness of breath for the past week. On physical examination, his temperature is 38.3° C. On percussion, there is dullness over the left lung fields. Thoracentesis performed on the left pleural cavity yields 800 mL of cloudy yellow fluid that has a WBC count of 2500/mm3 with 98% neutrophils and 2% lymphocytes. A Gram stain of the fluid shows gram-positive cocci in clusters. Which of the following terms best describes the process occurring in his left pleural cavity?

ExplanationBacterial infections often evoke an acute inflammatory response dominated by neutrophils. The extravasated neutrophils attempt to phagocytose and kill the bacteria. In the process, some neutrophils die, and the release of their lysosomal enzymes can cause liquefactive necrosis of the tissue. This liquefied tissue debris and both live and dead neutrophils comprise pus, or purulent exudate. Such an exudate is typical of bacterial infections that involve body cavities. Another term for purulent exudate in the pleural space is empyema. An abscess is a localized collection of neutrophils within tissues. Chronic inflammation occurs when there is a preponderance of mononuclear cells, such as lymphocytes, macrophages, and plasma cells, in a process that has gone on for more than a few days—more likely weeks or months—or that accompanies repeated bouts of acute inflammation. Edema refers to increased cellular and interstitial fluid collection within tissues, leading to tissue swelling.