Hello! I'm a 22yo female. Vegetarian diet. Healthy weight. I'm not a smoker. I was on vacation to Cancun, Mexico 2 weeks ago, when I noticed a strange mark on my thumb. The mark is blotchy and has a brown/red color to it mostly brown though. It's shiny in some areas and looks like dry skin in other areas, however I use lotion everyday. It does not burn, sting, or itch, it doesn't look irritated nor infected, and it has never swelled up. There are no bumps to it. It feels more rough compared to the surrounding skin. I have looked into dermatitis, eczema, melasma, and phytophotodermatitis. I was sure it was phytophotodermatitis due to me being in the sun and I probably had a margarita or a beer with lime in it, however it never hurt and it never blistered. It's about 1.5-2 inches long and it varies in width anywhere from 1/8 of an inch to 1/2 of an inch. It does not bother me, I'm just curious if anyone has any thoughts what it may be?