Extragenital lichen sclerosus: A comprehensive review

Lichen sclerosus (LS) is a chronic inflammatory mucocutaneous disease of unknown aetiology. About 85% of total cases of LS are genital cases, while extragenital form is seen in only 15-20% of cases. Extragenital LS (EGLS) can occur simultaneously with genital form; however, in 6% of the cases, only extragenital form has been described. Genetic, autoimmune, infectious, environmental and hormonal factors are implicated in its aetiology. Extragenital LS presents as asymptomatic white opalescent papules, which cluster in plaques and slowly progress over time resulting in parchment-like skin usually involving upper trunk, neck and shoulders. Lesions are frequently accompanied by purpura/haemorrhagic spots. The relationship with morphoea has been a topic of debate. Association with several autoimmune diseases has been observed. Diagnosis is usually based on clinical and dermoscopic examination and further supported by histopathological findings. LS needs to be differentiated from several other dermatological conditions such as discoid lupus erythematosus, vitiligo, mycosis fungoides (hypopigmented variant), lichen planus, graft-versus-host disease and morphoea depending upon the stage of the disease. Generally, extragenital LS is believed to lack carcinogenic potential. However, case reports with possible malignant transformation have been described. In this article, the authors have described a concise review of the extragenital form of LS.