Can Lichen Sclerosus Occur Outside the Vulva?
Yes, lichen sclerosus can occur on extragenital sites in 15-20% of cases, though the anogenital region remains the predominant location in 85-98% of patients. 1
Anatomical Distribution Patterns
Anogenital Involvement (Primary Sites)
- Females: The anogenital area is affected in 85-98% of female patients, typically presenting in a characteristic "figure-eight" pattern involving the vulva and perianal regions 1
- Males: The disease affects the glans, foreskin, and frenulum in 57% of cases, with meatal involvement in 4% and urethral extension in 20% 2
- Critical distinction: Perianal disease is common in females but extremely rare in males—this is an important diagnostic feature 1, 2, 3
Extragenital Sites (15-20% of Cases)
The most common extragenital locations include: 1
- Upper trunk (most frequent extragenital site)
- Axillae
- Buttocks
- Lateral thighs
Rarer extragenital sites documented include: 1
- Mouth
- Face
- Scalp
- Hands
- Feet
- Nails
Clinical Appearance at Extragenital Sites
- Extragenital lesions present as porcelain-white plaques similar to genital lesions 1
- May demonstrate follicular dells and areas of ecchymosis 1
- Can be difficult to distinguish from morphoea (localized scleroderma) at extragenital sites 1
Critical Clinical Distinction: Malignancy Risk
Extragenital lichen sclerosus does NOT carry a risk of malignant transformation to squamous cell carcinoma. 1 This is a crucial difference from anogenital disease:
- Anogenital lichen sclerosus: 4-5% risk of progression to squamous cell carcinoma, requiring long-term surveillance 1, 3, 4
- Extragenital lichen sclerosus: No documented cases of malignant transformation 1
Important Clinical Pitfalls
Vaginal Involvement
- It is traditionally taught that lichen sclerosus does not affect the vagina (unlike lichen planus) 5
- However, rare cases of vaginal involvement have been documented, particularly in patients with severe vulvar disease, significant vaginal atrophy, or pelvic organ prolapse with chronic vaginal wall exposure 5
- Vaginal lichen sclerosus may be underdiagnosed and more common than previously recognized 5
Biopsy Recommendations
- Biopsy is mandatory for all suspected lichen sclerosus to confirm diagnosis and rule out squamous cell carcinoma, regardless of location 1, 4
- This is particularly critical for anogenital lesions given the malignancy risk 1
- Extragenital lesions should also be biopsied to distinguish from morphoea and other conditions 1