Bruise-like ankles

My outer ankles are really dark. They look almost like bruises - a sort of purple-reddish color. They’ve looked this way a long time and they’re not sowllen and they don’t hurt, but my mom recently pointed it out to me. They’re a little dry. I’ve looked around but I really don’t know what it cpuld be. My best guess is that it’s caused by pressure when sitting criss cross apple sauce? I am fat - I do not say this disparagingly about myself, just a fact - so I wonder if that could be causing it - or some kind of hyperpigmentation? Really have no idea. Curious if any one else deals with this.