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File:IPLab6RA10.jpg|This is a high-power photomicrograph of another region with macrophages (right), fibrocytes (left), and occasional lymphocytes throughout the lesion.
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== Study Questions ==
* <spoiler text="What is pannus?">Inflamed and hyperemic synovium.</spoiler>
* <spoiler text="How common are rheumatoid nodules and what are they?">Rheumatoid nodules occur in 25% of patients with rheumatoid arthritis (RA). Rheumatoid nodules occur on pressure points (elbows, occiput, lumbosacral area, foot) and are composed of a central area of fibrinoid necrosis surrounded by a rim of epithelioid macrophages, lymphocytes, and plasma cells. The morphology of the rheumatoid nodule is similar to the tissue reaction seen in the joints.</spoiler>
* <spoiler text="The exact pathogenesis of rheumatoid arthritis (RA) is not known. What are some of the factors that are associated with RA?">Genetic susceptibility, exposure to a primary exogenous arthritogen, an autoimmune reaction within the synovial membranes, and release of cytokines that mediate joint damage.</spoiler>
* <spoiler text="What is rheumatoid factor?">IgM antibodies (perhaps originating from the joints) that are directed against the Fc portion of autologous IgG.</spoiler>
{{IPLab 6}}
[[Category: IPLab:Lab 6]]