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Wegener’s granulomatosis and microscopic polyangiitis

Video transcript
Voiceover: Wegener granulomatosis is a small vessel vasculitis. The vessels that are affected are isolated to the lung, the nasal passage, and really the entire tract down through the lung. The kidneys are affected. Really lung, and the tract, and the kidneys are affected in Wegener granulomatosis. Think about what happens if you damage anything along this tract along with the kidney. If you damage small blood vessels in the nasal passage, you may get bloody nasal discharge. If damage gets severe enough, you can cause disruption and deformity to the nose. It'll look like it's caved in. You'll get more of a curled nose. That's called saddle nose deformity. You may see other symptoms like chronic sinusitis. Constant inflammation in the sinuses causes this chronic pain and this blockage of sinuses due to swelling. You can really get problems in your trachea, so the windpipe itself may get constricted and it may become difficult to breathe so you have this collapsed trachea. Of course you might get bloody sputum, or bloody spit, or bloody coughing because because both your lungs are damaged. Remember, if it's a small blood vessel disease, there really isn't much in the way if it ruptures. Take a look. Here's a small blood vessel. These two lines represent the vessel wall. Blood cells pass through. If you rupture this wall, cells escape really readily. That's why you can get blood in your lungs, blood in your nose, and that sort of thing. Symptoms such as the saddle nose deformity and the collapsed trachea are from decreased blood to those tissues so they die. It's a necrotizing vasculitis. Cell death, that's what necrosis means. You also see this occurring in the kidney as well. This damage causes decreased filtering of the kidney. You may have blood volume increase because blood can't really get out and go through the filtration system, which is the renal system, the kidneys. You might see increased blood pressure and decreased urine output. Decreased urine because you're no longer filtering. This disease I like to remember with the letter C. In fact, I like to think Wecener's granulomatosis to really remember all of the symptoms that are involved. If you draw a big C on this body, you can remember that the nasal passage, the trachea, the bronchi, the lungs are all affected and the kidney is affected too. In fact I drew these little kidneys as a C so you can remember that too. You've got this lung, nasal passage, and and this entire tract and kidney involvement. Another important thing to note is the involvement of antibodies known as cANCA. ANCA stands for anti-neutrophilic cytoplasmic antibodies. Remember in vasculitis white blood cells are going haywire and releasing a lot of immune proteins that can cause damage. All this material is coming from inside of these white blood cells. It's important to note these white blood cells are known as neutrophils. These components come from the cytoplasm or in other words the inside of the neutrophils. It's from the cytoplasm of the neutrophils. B cells which are white blood cells responsible for the creation of antibodies see all this material and release a lot of antibodies. Along with cANCA, we also have another type of ANCA called pANCA. Basically they're responding to different components within the neutrophils. These immune proteins that are being released aren't just one type of protein. There's many different things that are released from inside of the cytoplasm of the neutrophil. Different types of antibodies, pANCAS or cANCAS, can be created. Ninety percent or more of patients are noted to have cANCA when they have Wegener's. This is a good way to test for somebody who has Wegener's. Using c as a mnemonic is also good for remembering the treatment. One of the treatments is corticosteroids. The other treatment is cyclophosphamide. These both act by inhibiting the immune system. They are the treatment for Wegener's granulomatosis. To diagnose Wegener's granulomatosis, you need to have evidence of cANCA and you also usually puruse a biopsy. What's a biopsy? It's when you take a cross section of a tissue, such as in the kidney, and look at it under a microscope. What do you see under the microscope? Under the microscope you'll see granulomas. Wegener granulomatosis. What's a granuloma? It's when you have white blood cells working together to form a circle or a sphere around something they think is foreign. It's a way to block off whatever this material is on the inside. When your immune system can't break it down or destroy it, it essentially hides it from the rest of the body and prevents it from escaping. This is known as a granuloma. That's real easy to remember because of the name Wegener granulomatosis. Aside from granulomas, in the kidney you can see the glomeruli being affected. What's a glomeruli? In the kidney, you have these little balls called glomeruli. You've got blood vessels that go around them. The glomeruli act as a filter to filter the blood. What happens in Wegener granulomatosis? The blood vessels in the glomeruli get really inflamed. This inflammation starts to affect the entire glomerulus so you see swelling. The swelling pushes the glomerular membrane and creates this crescent shape. Remember this is a glomerulus. This is how your kidney filtrates. You get this crescent shape. That is our other c that we can think of when we're talking about Wegener granulomatosis. On biopsy you can see crescent formation in the kidney. That's really a good mnemonic to remember Wegener's granulomatosis. Let's go ahead and actually move this further down so we can make room for this other disease. It's called microscopic polyangiitis. Many blood vessels are affected. It's microscopic so you want to think small vessel vasculitis just like Wegener's. Microscopic polyangiitis is different from Wegener's because you see pANCA instead of cANCA. Around 80 percent of the patients will have this pANCA. Why you get a different type of ANCA, anti-neutrophilic cytoplasmic antibody is really unknown. It's a good way to tell the difference between these two. Another great way to tell the difference is microscopic polyangiitis only affects the lungs and the kidneys. There is no nasal, or pharynx, or tracheal involvement. In other words no nasopharyngeal involvement. It's really confined down to the lungs and the kidneys. Lastly on biopsy there are no granulomas seen. Whereas in Wegener's, of course, you have granulomas if you remember the name, Wegener's granulomatosis. Those are ways you can differentiate between these two diseases when you're considering vasculitis for your diagnosis.