Description

• Lichen sclerosus (LS) is an uncommon chronic inflammatory mucocutaneous condition. LS shows a predilection for the anogenital area, most commonly affecting the vulva in women and the glans and foreskin in men.
• Extragenital lesions constitute about 15–20% of all cases of LS and usually involve the neck, shoulders, arms, and upper trunk. Rarely, other sites may be affected such as the oral mucosa, plantar surface, and nails.

Epidemiology

Incidence
LS is a rare entity. Occurs at all ages and in both genders, but a higher incidence is present in postmenopausal women (49% of cases are in women >50 years). Pediatric disease makes up 7–15% of all cases (1). The female to male ratio is between 3:1 and 10:1. It is more common in white patients than in those who are Hispanic or black.

Prevalence
The exact prevalence is unknown but is estimated to be between 0.1% and 0.3% among patients referred to a community-based dermatology department and 1.7% of patients in a general gynecology practice (1).

Etiology and Pathophysiology

• The etiology of LS is unknown. Some studies have shown a link between autoimmune diseases and LS in women. A study showed coexisting autoimmune disease in 30% of patients with LS compared to 10% with autoimmune disease in patients without LS (2).
• A recent study analyzed serum autoantibody profiles in patients with LS and compared them to healthy controls. Autoantibodies directed against specific skin protein and molecules such as extracellular matrix protein 1 (ECM1) were demonstrated in most patients with LS, making ECM1 a tentative target for autoimmune mechanisms in LS.
• Additionally, an autoimmune phenotype involving immunologic changes on the level of T and B cells and increased levels of TH1-specific cytokines with resultant dense T-cell infiltration and enhanced BIC/miR-155 expression has been observed.

Genetics
About 10% of patients with LS have relatives with the same condition, especially mother and daughter. Nevertheless, the pathogenetic relevance of these findings is uncertain. Oxidative changes in the DNA and TP53 mutations (tumor suppressor gene) have also been described, and the chromosome involved is the 17p13.1.

Risk Factors

Menopause, chronic friction and scratching (including being uncircumcised), trauma including radiation or urogenital surgical procedures or sexual abuse during childhood, and infections (vulvitis/urethritis) are considered risk factors for the development of LS.

General Prevention

No clear preventive methods are reported in the current guideline; however, early aggressive treatment may prevent disease progression.

Commonly Associated Conditions

20–30% of women with LS also have autoimmune diseases. Thyroid dysfunction is the most common (12–16%); inflammatory bowel diseases, pernicious anemia, alopecia areata, rheumatoid arthritis, morphea, and scleroderma have been associated with LS in women, whereas in men, conditions such as diabetes mellitus and atopic dermatitis commonly coexist with LS.