IPLab:Lab 3:Foreign Body Granuloma

Clinical Summary

This 21-year-old black male suffered a gunshot wound to his right chest. A thoracotomy revealed multiple bleeding points in the middle and lower lobe of the right lung and significant hemorrhage from an intercostal artery. A portion of the right middle lobe was removed. The patient's post-operative course was complicated by Gram-negative pneumonia and significant neurologic dysfunction, apparently the result of emboli from iliofemoral venous thrombosis. All were treated without sequelae.

Images

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  This is a low-power photomicrograph of lung and pleura. There is some hemorrhage in this tissue (arrows), probably the result of surgery or the gunshot wounds.

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  This higher-power photomicrograph demonstrates the small focal cellular lesions (arrows) found throughout the parenchyma of the lung.

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  A higher-power photomicrograph of these granulomas reveals that they surround blood vessels (note the red blood cells within the lumen) (arrow).

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  This is a photomicrograph of lung taken under light that is partially polarized to demonstrate the birefringent particles within the granulomas (1). Also, at this magnification one can better appreciate that these granulomas are adjacent to blood vessels (2).

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  This is a fully-polarized view of lung showing numerous birefringent particles.

Study Questions

• Compare and contrast the tissue reactions to carbon (anthracosis), talc, and silica. What factors are important in the pathogenesis of tissue injury due to these foreign materials?

Carbon is relatively inert and leads to little if any tissue damage.

Talc results in foreign body granulomas but these lesions are mild.

Silica can lead to severe fibrosis of tissues, especially the lung.

Factors important in tissue injury include:

• size of particles (for airborne particles the small size lets them get deep into the lung),
• solubility of material,
• cytotoxicity of material (e.g. silica reacts with free radicals and other chemical groups to cause membrane damage), and finally
• whether the materials can be phagocytosed and removed from the body or whether they damage leukocytes and cause the release of inflammatory mediators.

• What are the birefringent particles seen in the nodules adjacent to the vessels and how did they get there?

The material is talc, which is often used to "cut" street drugs. Intravenous injection of talc leads to some talc being deposited in tissues and initiating an inflammatory response.