This is unknown but local conditions have a role: not only does skin develop the disease after being transplanted into affected areas, but the disease goes away when the grafted skin is returned to a distant site.
The affected areas on the vulva, penis (Fig. 13.38), perineum and/or perianal skin show well-marginated white thin fragile patches with a crinkled surface. Itching can be severe, especially in women. The fragil-ity of the atrophic areas may lead to purpura and erosions. Scratching can cause lichenification, and diagnostic confusion.
Women are more commonly afflicted than men, but pre-adolescent girls and boys also can develop this problem. In girls, the white patches circling the vulva and anus take on an hourglass shape around the orifices.
As time goes on, scarring occurs. In adult women, the clitoral prepuce may scar over the clitoris, and the vaginal introitus may narrow, preventing enjoyable sexual intercourse. Scarring is rare in girls and boys; treatment may prevent it occurring in adults.
The sharply marginated white patches of vitiligo can afflict the vulva and penis but lack atrophy, and typical vitiligo may be found elsewhere on the body. Neurodermatitis may be superimposed upon lichen sclerosus after incessant scratching.
Biopsy is often unnecessary but the appearances are distinctive. The epidermis is thin, the basal layer shows damage, and the papillary dermis contains a homo-geneous pink-staining material and lymphocytes.
At first sight it might seem unwise to rub potent topical steroids onto atrophic thin occluded skin. Yet, treatment with potent topical steroids not only reduces itch, pain and misery, but also reverses hypo-pigmentation and atrophy by shutting down its cause. However, atrophy, striae and other complications can develop on untreated adjacent skin, if the medication spreads there. Ointments are preferable to creams. Only small amounts (15 g) should be dispensed. After a course of 8–12 weeks, weaker topical steroids can be used to maintain a remission.
As mentioned earlier, scarring can destroy anatomical structures and narrow the vaginal opening. Squamous cell carcinomas may develop in men as well as women. Any focal thickening needs a biopsy.