IPLab:Lab 1:Lung Abscess

Clinical Summary

This 67-year-old male with advanced colon cancer developed obstruction of the bowel and underwent palliative surgery to remove an 8-cm portion of colon containing the obstruction. During the surgery the patient had several episodes of hypotension. After surgery he did not regain consciousness and required ventilator support. Four days after surgery, the patient developed a fever and his white blood cell count was found to be 15,256 cells/mm³. Thus, he was started on broad-spectrum antibiotics. A chest x-ray demonstrated infiltrates in both lungs, which worsened over the next several days. His overall condition continued to deteriorate and he died 12 days after surgery.

Autopsy Findings

At autopsy, metastatic colon cancer was found throughout the abdominal cavity and invading into the liver. The lungs were markedly consolidated and had several focal abscesses that were 2 to 4 cm in diameter. Liquefied material poured out from inside these abscesses when the lungs were sliced.

Images

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  This is a gross photograph of the lungs from this case. Note the abscesses (arrows) especially in the lower lobes. The entire lung is consolidated.
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  This is a closer view of the lung from this case. In this section of upper lobe there are multiple areas of early abscess formation (arrows). Note the circumscribed whitish-tan lesions. These lesions are filled with white blood cells.
• 
  This low-power photomicrograph of lung from this case demonstrates one of the abscesses (arrows). Note that the material inside the abscess has been expelled.
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  This higher-power photomicrograph of lung demonstrates the edge of the abscess. Note the loss of material from the center of the abscess (1) and loose necrotic material that has not been expelled (2). This material is made up of inflammatory cells (primarily dead white blood cells) and necrotic lung tissue.
• 
  This is a low-power photomicrograph of lung tissue containing a large abscess. The center of the abscess contains necrotic debris (1) and there is a rim of viable inflammatory cells (arrows) surrounding this abscess.
• 
  This high-power photomicrograph demonstrates a small abscess (arrow) with a necrotic center.
• 
  This high-power photomicrograph shows the center of an abscess containing neutrophils and necrotic debris.
• 
  A high-power photomicrograph of lung from this case demonstrates a small abscess full of inflammatory cells (primarily neutrophils) (arrows). There is a bacterial colony in the center of this abscess (1).

Study Questions

• What factors predisposed this patient to pneumonia?

The patient had terminal cancer, had undergone a major surgery, and was on a ventilator. Any of these factors could have predisposed the patient to pneumonia. Also, being a patient in the hospital is itself a risk factor due to nosocomial infections.

• What causes abscesses to liquefy?

The proteolytic enzymes released by white blood cells digest the tissue and cause it to liquefy. The presence of bacteria accentuates the inflammatory response and the bacteria themselves can also release enzymes that digest the tissue.

• Had the patient lived, could these lesions have resolved?

If the patient had lived, the body could have eventually removed all of the necrotic and liquefied material. However, since there was loss of tissue and disruption of the basement membranes, many of the lesions would heal by scar tissue. So, the lung would never return to its original normal morphology and function.

Additional Resources

Reference

• eMedicine Medical Library: Empyema and Abscess Pneumonia
• Merck Manual: Lung Abscess

Journal Articles

• Brandenburg JA et al. Clinical presentation, processes and outcomes of care for patients with Pneumococcal pneumonia. J Gen Intern Med 2000 September; 15(9): 638–646.

Images

• PEIR Digital Library: Lung Abscess Images
• WebPath: Pulmonary Pathology Images

Related IPLab Cases

• Lab 3: Lung: Lobar Pneumonia
• Lab 3: Lung: Bronchopneumonia

Palliative surgery provides alleviation but is not curative.

A normal white blood cell count is 4000-11,000 cells/mm³.

An infiltrate is an accumulation of cells in the lung parenchyma--this is a sign of pneumonia.

Consolidation is the filling of lung air spaces with exudate--this is a sign of pneumonia.

An abscess is a collection of pus (white blood cells) within a cavity formed by disintegrated tissue.

An abscess is a collection of pus (white blood cells) within a cavity formed by disintegrated tissue.

In alcoholics, aspiration pneumonia is common--bacteria enter the lung via aspiration of gastric contents.