INFLAMMATION/HEALING II

Slide 19 [WinLab] [Mac] [WinHome]

An "Unknown"

Spend a few minutes trying to figure out what’s going on here. It’s a variation on a basis theme that you’ve already learned.

• Begin by identifying the organ represented.

• Under scanning power, describe what looks unusual about this tissue.

• On the higher power of your scope, describe the abnormalities in any one of the areas where the normal tissue seems to have disappeared. In the center of each of these areas there is abundant cellular debris with just enough viable cells left to identify the predominant cell population.

• In your slide, you should be able to find a large blood vessel containing a fibrin clot with many included clumps of leukocytes. At the edges of this clot there is evidence of organization (more about this later) and a scattering of chronic inflammatory cells. The same is true around many of the destructive lesions within the parenchyma.

• Can you imagine the gross appearance of this tissue? Can you devise a clinical scenario that might account for what you have seen on this slide?

Slide 20 [WinLab] [Mac] [WinHome]

Spleen: Granulomas (sarcoidosis)

• Under the scanning power you should be able to identify the splenic capsule. The usual architecture of red and white pulp, however, is replaced by multiple pink staining nodules, each with a surrounding blue halo of inflammatory cells. Closer inspection will reveal that each of these nodules consists of an aggregate of peculiar looking macrophages (“epithelioid” cells) and multinucleated giant cells. Each of these nodular masses is surrounded by a zone of lymphocytes.

• Why do these lesions qualify as granulomas? Compare these lesions to those seen in Slide 3 [WinLab] [Mac] [WinHome], noting similarities and differences.

• In what sorts of situations might you encounter granulomatous inflammation? How could you go about demonstrating the possible causative agents in granulomas?

Slide 21 [WinLab] [Mac] [WinHome]

Perivascular soft tissue: Foreign Body Granuloma

This specimen comes from a patient who had had a surgical procedure in the region many weeks before this specimen was obtained.

• Under scanning power you will note cross sections of a large vessel with adjacent scar tissue surrounding some very obvious fibrillar foreign material. Under closer inspection you will note that the clusters of fibrils are surrounded by scar and by a population of striking multi-nucleated giant cells. The propensity of these giant cells to surround and engulf foreign material is obvious. A scattering of other inflammatory cells is also present.

• What is the origin of these multi-nucleated giant cells?

• Would all foreign material evoke this type of response?

Slide 22 [WinLab] [Mac] [WinHome]

Colon: Organizing Fibrinopurulent Peritonitis

This specimen was obtained at autopsy of a patient who had a peptic ulcer which penetrated, leading to a soiling of the peritoneal cavity.

• Try to identify the various layers of the bowel wall. The peculiar appearance of the mucosa is largely due to postmortem autolysis (you will note no inflammation associated with the mucosal change).

• Direct your attention to the serosal surface, remembering that the normal serosa would consist of a flattened layer of mesothelium over a thin layer of connective tissue. In this case, the mesothelial layer has been destroyed and the outer surface of the colon is ensheathed in a layer of fibrin (the pink fibrillar material), and neutrophils, constituting a fibrinopurulent exudate.

• Between the fibrinopurulent exudate and the colonic wall is a zone of proliferating capillaries and fibroblasts with interspersed inflammatory cells. This is granulation tissue beginning to organize the exudate.

• What does the presence of the granulation tissue tell you about the age of the inflammatory process?

• Had the patient survived, what would the ultimate fate of the exudate be? What might be the sequelae and complications of this process in a surviving patient?

Slide 23 [WinLab] [Mac] [WinHome]

Vaginal Apex: Granulation Tissue

This specimen was obtained from a 38-year-old woman who had undergone a vaginal hysterectomy some weeks before. During a follow-up examination, a red nodule was noted at the apex of the vagina in the area of the healing incision. This slide represents that nodule.

• No normal tissue can be identified in this slide. The entire specimen is the result of the inflammatory and reparative process.

• The tissue in this instance is basically the same as that layer that you noted beneath the fibrinopurulent serosal exudate in the preceding slide. Basically the tissue consists of proliferating vessels of various sizes with diffusely interspersed fibroblasts. The pink intercellular material represents edematous ground substance in this immature connective tissue. There is a diffuse infiltrate of leukocytes including neutrophils, macrophages, lymphocytes, and especially prominent plasma cells. Be certain that you can identify each of these cell types.

• What is the significance to the patient of a lesion such as this in a healing incision?

Slide 24 [WinLab] [Mac] [WinHome]

Skin and Subcutis: Chronic Ulcer

This slide represents a non-healing scalp lesion from a 43-year-old man.

• Note under the scanning power of your microscope that the cutaneous surface is interrupted by a defect which penetrates deep into the tissue. Note, also, under the scanning power that there is a layer of exudate surfacing this defect with an underlying loose tissue and then an outer “shell” of dense fibrous tissue.

• Under the higher powers of your microscope note that the ulcer is lined by loose fibrinopurulent exudate, immediately beneath which is a zone of maturing granulation tissue (with various types of leukocytes), deep to which is a zone of relatively mature scar.

• How do you suppose the age of this lesion compares with those in the preceding two slides?

• This lesion is good example of chronic inflammation with evidence of advanced scarring as well as continued exudation. An inspection of the epidermal borders of the lesion will reveal attempted regeneration of the epithelium.

• Were this lesion finally to heal, what would be the sequence of histologic events and what would be the ultimate appearance?

Slide 25 [WinLab] [Mac] [WinHome]

Skin: Scar

This 27-year-old patient had a pigmented skin lesion biopsied which turned out to be a melanoma. The specimen in this slide represents a wider excision of the biopsied area a few weeks after the diagnosis was made. There is no remaining neoplasm, but a scar is evident.

• Under the scanning power of your microscope identify the epidermis and, at either end of the specimen some of the dermal appendages. Note that in the central portion of the specimen dermal appendages are absent and a dense connective tissue “replaces” the dermis. This is a scar. Note that the epidermis over the area of scar shows flattening of the normal rete ridge pattern seen towards the ends of the specimen. This is regenerated epidermis over the scar.

• Relate these histologic features to the gross appearance of the area.

• A quick glance at Slide 26 [WinLab] [Mac] [WinHome] will reveal an abnormal variation on this same theme. This specimen represents a large nodule which developed in a surgical incision. You will note from the shape of the lesion that this was a “knob” projecting from the skin surface, covered with an intact (regenerated ) epidermis. This is a keloid, actually a nodule of overgrown scar tissue. Under the higher power of your scope note the peculiar coarse, glassy collagen which accounts for the bulk of the keloid. What is the significance of such a lesion?

Slide 27 [WinLab] [Mac] [WinHome] shows another complication of healing, namely a traumatic or “amputation” neuroma. This was a nodule developing in a surgical scar. It consists of a tangle of regenerating peripheral nerve fibers and entrapped in dense collagen. What is the significance of such a lesion?