mass of petechiae or a rash?

i just woke up and found a 4x4 inch solid red mass on my lower leg. it looks like almost solid petichiae - but then again, it could be a rash? it isn't itchy, it is flat, and i'm up at an higher altitude than usual (over 5000 feet.). but i've been at this altitude before without this happening, in fact, i've been as high as 8000 feet in the last week or so. what's also odd about it - i had some scrapes on that area last week, and those areas which still have some minor scabs - are totally clear.
any ideas?

I sometimes wake up with a rash. I also live at a high altitude (Calgary) and the air tends to be very dry. It MAY be that you "itched" in the night and rubbed it without realising it.Just keep an eye on it and see if it gets worse. C

Oh, I've had that. Mine is about 4 inches by 2 inches, like a rectangle. Just above my ankle. Same thing here, red and almost looks like a rash but it's flat agains my skin and doesn't itch.I've had it a couple of times but it would always go away before the doc could see it. I don't live at a high elevation, I'm in Central Ohio. Here's a couple of things I've wondered about though. I was on NPlate and Rituxan at the same time, I stand on my feel ALOT! & I wear knee high trouser socks but roll them down around my ankles. Do you do any think like that?