CELL AND TISSUE INJURY II

Slide 8 [WinLab] [Mac] [WinHome]

An "Unknown"

• Spend a few minutes trying to figure out what's going on here. Basically, it's a process you've seen before.

• Begin by identifying the organ/tissue represented.

• Under the lowest power of the scope, identify the abnormal zone. Describe how the tissue elements in this abnormal zone differ from the normal.

• What is going on at the border between normal and abnormal?

• Put the elements of your description together into a diagnosis, i.e., the basic abnormality.

• What might have triggered the abnormality?

• Any ideas as to the possible clinical manifestations?

Slide 9 [WinLab] [Mac] [WinHome]

Lung: Cytomegalovirus Infection

This lung was obtained at autopsy of a 28-year-old patient with AIDS.

• What histologic features allow you to identify this tissue as lung?

• Note that the alveolar spaces do not appear “empty” (i.e., air-containing) as in normal lung. What can you identify in many of the alveoli? How would filling up the alveoli be manifested radiographically?

• Under relatively low power, you can readily identify cells infected with CMV. They are very large (“cytomegalo”) and contain huge intranuclear inclusions. The cytoplasm of some of these enlarged cells may also be seen to contain granular inclusions. The appearance of these cells is typical of CMV infection.

• In what other tissues might you see similar CMV-infected cells?

• What sorts of patients are at risk for developing clinically significant CMV infections?

• What sorts of subjects are commonly exposed to CMV?

• Is CMV a cytopathic or oncogenic virus?

Slide 10 [WinLab] [Mac] [WinHome]

Perianal Region: Condyloma

This specimen was trimmed from the region of the anus of a 28-year-old man. Clinically, the lesion had the appearance of a large, warty excrescence or mass.

• Note under low power that the tissue is arranged in coarse papillary projections. The squamous epithelium is much thicker than normal due to an increased number of cells, squamous cells stimulated to proliferate by infection with a papilloma virus (rather than being killed).

• A histologic “marker” for the presence or papilloma virus is so-called “koilocytosis”-- the presence of squamous cells with a peri-nuclear halo surrounding a slightly altered nucleus.

• Aside from condyloma, what sorts of lesions can be associated with infection by one or another strain of human papilloma virus?

• How are papilloma viruses spread from one subject to another?

Slide 11 [WinLab] [Mac] [WinHome]

Lung: Metastatic Calcification

This slide demonstrates calcium deposits in tissue. Low power examination of this section of lung reveals widespread basophilic deposits of calcium which differ somewhat in their texture…ranging from crystalline in the heavier deposits to granular in the less dense areas.

• In what structures are the calcific deposits?

• How do you account for their presence?

• What is the primary mechanism for metastatic calcification to occur? Dystrophic calcification?

• Other than the calcific deposits, what histologic abnormalities are present in this specimen?

Slide 12 [WinLab] [Mac] [WinHome]

Artery: Atherosclerosis (with dystrophic calcification)

These sections of arteries came from a 62-year-old hypertensive diabetic who had generalized lesions of this sort.

• Compare these cross-sections of arteries to your recollection of similar views of normal vessels -- first in terms of wall to lumen ratio. You’ll note that what was once lumen is markedly narrowed by atherosclerotic plaque consisting of amorphous material, cholesterol deposits, cells derived from the arterial media, and collagen produced by these cells.

• The extracellular crystalline deposits of cholesterol appear as “cholesterol clefts.” Why do these appear empty?

• Note the basophilic deposits of calcium within the plaques. These are dystrophic deposits. How do they qualify for this designation? Some of your sections may also contain calcium deposits in the arterial media. Dystrophic calcification of sclerotic arteries is a very common form of “pathologic calcification.” What are some other common sites for dystrophic calcification?

• What are the major consequences of atherosclerotic lesions of this sort?

Slide 13 [WinLab] [Mac] [WinHome]

Liver: Hemochromatosis

This section of liver is from a 46-year-old male who was found to have an enlarged, firm liver and diabetes mellitus. He was subsequently diagnosed as having hemochromatosis, an iron-overload disorder.

• How can you identify this section as liver? What is unusual about the architecture?

• Note the accumulation of brown granular pigment within hepatocytes, bile duct epithelium, macrophages, and connective tissue. This pigment is hemosiderin. Most of the stored material is intracellular, but there are also scattered extracellular deposits in the connective tissue. These are associated with occasional calcific deposits, and with multinucleated giant cells. Other than in hemochromatosis, under what conditions would you expect to encounter hemosiderin in tissues?

• Other brownish pigments that might be encountered in tissue include bilirubin, lipofuscin, and melanin. What are the origins of these? What test would identify a pigment as iron-containing hemosiderin?

• Can you account for the fact that patients with hemochromatosis are sometimes called “bronze diabetics”?

• What features characterize cirrhotic livers in general?