Vulvar lichen sclerosus

Lichen sclerosus is a long-lasting skin disease that shows up mostly in the genital area. When it affects the vulva, the outer part of the female genitals, it's called vulvar lichen sclerosus. It's an inflammatory disease, meaning the skin stays irritated from the inside, and it's considered autoimmune: the body's own defenses turn against it by mistake. The affected skin gets thinner, which is called atrophy, and loses pigment, the substance that gives skin its natural color. That loss is called hypopigmentation.

Here's what happens underneath. The skin contains T lymphocytes, or T cells, a type of infection-fighting white blood cell, and they're already activated. They release cytokines, chemical messages that cells use to talk to each other. Those messages switch on fibroblasts, the cells that make collagen, the protein that gives skin its firm padding. But the collagen they turn out is altered, and it leads to fibrosis, tissue that's a lot like scar tissue. On top of that, there are fewer capillaries, the tiniest blood vessels that supply the skin.

You can actually see that change. Typically, it first shows up as a red patch with sharp edges, called erythema, which later turns into plaques, flat areas of changed skin that are thin and as white as ivory or porcelain. Think of a piece of fabric that's been washed over and over: it ends up thinner and paler than the rest of the garment. And what people feel most is itching, which is often worse at night.