Clinical overview
Lichen sclerosus (LS) is a chronic, inflammatory, lymphocyte-mediated dermatosis with predilection for the anogenital region of women, particularly postmenopausal women but also prepubertal girls. It is the single most common cause of severe vulval itch in the older woman, the most under-diagnosed cause of postcoital bleeding, dyspareunia, and labial scarring, and — critically — carries a 4–5% lifetime risk of progression to differentiated vulval intraepithelial neoplasia (dVIN) and subsequent vulval squamous cell carcinoma. Every clinician examining a vulva should be able to recognise it, treat it adequately, and arrange long-term surveillance.
The chapter is a description of the pathology and how that pathology produces the clinical features. Management is summarised but the surveillance and malignant-potential elements are emphasised.
Core knowledge
Aetiology and pathogenesis
Multifactorial. Current model:
- Autoimmune basis — increased prevalence of other autoimmune diseases (thyroid disease, vitiligo, alopecia areata, pernicious anaemia). T-cell mediated damage to basal keratinocytes and basement membrane. Circulating autoantibodies (e.g., to extracellular matrix protein 1, ECM-1) in many patients.
- Genetic susceptibility — HLA associations (HLA-DQ7).
- Hormonal — typically a postmenopausal hypoestrogenic environment, although LS occurs in prepubertal girls and rarely in reproductive-age women.
- Local trauma — Koebnerisation (lesions developing at sites of injury, friction, scratching, episiotomy scar).
- Infection — Borrelia link investigated and discounted in most populations.
Histopathology (the diagnostic appearance)
The diagnostic biopsy pattern stacks hyperkeratosis, a flattened epidermis, hyalinised dermis, and lymphocytes.
Three classic layers visible on biopsy of a developed lesion:
- Hyperkeratosis with follicular plugging — thickened keratin at the surface.
- Atrophic epidermis with loss of rete ridges — epidermis is thinned and flattened.
- Subepidermal hyalinisation — a homogeneous, pale, eosinophilic band in the upper dermis ("pink zone").
- Lymphocytic infiltrate beneath the hyalinised band.
Early lesions may only show the lymphocytic infiltrate without the hyalinisation; biopsy timing matters. In long-standing disease, the architecture is so distorted that biopsy may yield only fibrotic tissue, but the diagnosis is then clinically obvious.
Clinical features explained by the pathology
