I used to have them as a kid, but thought they were gone completely. Exfoliating regularly prior to starting HRT made me realise that they might still exist, but you had to know about them in order to spot that. Queue in HRT and they're back, not quite as extreme as way back when, thank goodness, but visible to the world. Basically your upper skin becoming thinner seems to allow the pigment patches to shine through again. 🙂