Systemic GVHD

A friend of mine with skin GVHD emailed me a good explanation of what "systemic" GVHD means:

"Systemic just means that his GVHD is effecting or can effect his whole body or "system". GVHD is capable of effecting your entire body and all your systems within it. Just because a person only manifests the disease in say their skin or mouth doesn't mean it isn't present or potentially having effects on other parts of his body. An example of this is that I have had little or no symptoms of gut GVHD, however when they recently did a biopsy of my stomach lining during a endoscopy, there were signs of GVHD present. This is a clear indication that the GVHD is "systemic" or system wide, though only problematic in my skin and connective tissues mostly. Essentially what I think the doctor is saying is that GVHD though only severe in his skin, is quite capable of having effects other ways and in other areas of his body. When you have GVHD you have it "system wide," even though it only perhaps is severe enough to show up in your skin or other more common places."