Psoriasis usually shows up in early adulthood, around college age (as was the case for me). It can also appear in younger children or it might not manifest itself until well past the college years (remember the one thing you can safely predict about psoriasis: it’s unpredictable).
Usually psoriasis will appear gradually, affecting skin around the scalp and elbows. It seems like a harmless rash at first, like an allergic reaction. But from that point the skin will oftentimes worsen both in appearance and in general irritability. Affected areas of the skin can become any combination of swollen, itchy, red, dry, flaky or scaly.
Unfortunately scraping off the dead skin will not discourage the disease — this actually tends to exacerbate the situation, as scratched skin can become infected and thus even more inflamed.
When you start to suspect that something is wrong, you should probably make an appointment with your dermatologist to determine conclusively whether you have psoriasis so you can make purposeful, informed decisions from that point forward.