Background
Lichen sclerosus (LS) is a chronic inflammatory dermatosis that results in white plaques with epidermal atrophy. Lichen sclerosus has both genital and extragenital presentations. It is reported under a variety of other appellations such as lichen sclerosus et atrophicus (dermatological literature), balanitis xerotica obliterans (glans penis presentation), and kraurosis vulvae (older description of vulvar presentation). An increased risk of squamous cell carcinoma may exist in genital disease, but the precise increase in risk and what cofactors (human papillomavirus infection or prior radiotherapy) may be involved are not yet completely defined. In large series, genital presentations, both vulvar and penile, outnumber extragenital reports by more than 5:1.
Pathophysiology
Inflammation and altered fibroblast function in the papillary dermis leads to fibrosis of the upper dermis. Genital skin and mucosa are affected most frequently, but extragenital lichen sclerosus does occur, and even rare oral presentations are reported. Several studies have recently identified the presence of autoantibodies to the glycoprotein extracellular matrix protein 1 (ECM1).[1] This may be associated with histologic evidence of vasculitis in some cases and may lead to reduplication of the basement membrane in blood vessel walls.[2] The exact role of these antibodies and the changes seen in the microvasculature are currently under investigation.[3] The role that hypoxia and ischemia have in the initial cellular and vascular damage is supported by the finding of increased glut-1 and decreased vascular endothelial growth factor (VEGF) expression in affected skin.[4]
The effect of cell-mediated cytotoxicity has been better defined at the biochemical level.[5] Systemic disease or involvement of other organ systems, unlike scleroderma, is not described, although many more authors are describing lichen sclerosus and scleroderma as closely related entities; many cases of coexistent lichen sclerosus/scleroderma having been reported.
Epidemiology
Frequency
International
The population rate is unknown. Male genital lichen sclerosus is seen almost exclusively in uncircumcised or incompletely circumcised men and boys. The rate of circumcision in a given population would thus influence the rate in this subset.
Mortality/Morbidity
Lichen sclerosus has no associated increased mortality unless the patient develops a malignancy in the area. Cancer arising in extragenital presentations is described only rarely and may be coincident with other factors. Many pediatric cases will improve with puberty, although other expressions of vulvodynia may persist. In contrast, some authors suggest the rate of spontaneous resolution may be lower than 25%.[6] Extragenital cases and many genital cases are asymptomatic except for the cosmetic aspect or pruritus. Recalcitrant cases, especially those associated with erosion or progressive scarring, may result in severe sexual dysfunction.
Race
Lichen sclerosus, both genital and extragenital, has no known racial predilection. A genetic predisposition, based on family clustering, is apparent.[7]
Sex
The male-to-female ratio is 1:6, with female genital cases making up the bulk of reports.
Age
Up to 15% of cases are in children with the majority being vulvar presentations. A study of foreskins submitted after therapeutic circumcision for phimosis revealed many cases of unrecognized lichen sclerosus. Extragenital lichen sclerosus is rare in children.
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