Track: Case Reports

Topic: Inflammatory Diseases

Abstract:

A 50-year-old female presented with a 4-year history of vulvar pigmented lesions and was referred to our department by her local gynecology clinic with suspicion of vulvar melanoma in situ. The patient has no significant past medical history. Physical examination revealed widespread, irregular, dark brown macules on both the skin and mucosa of the external genitalia. Areas of depigmentation were also observed on the affected skin. Skin biopsy of the pigmented lesion revealed a mild increase of melanocytes without atypia in the basal layer, melanin deposition in the basal layer keratinocytes, melanin incontinence just beneath the epidermis, and mild perivascular lymphocytic infiltration in the superficial dermis.

Pathological examination of the re-biopsy specimen revealed focal lichenoid reaction and very subtle sclerosis just below the epidermis, leading to a diagnosis of lichen sclerosus sine sclerosis. Subsequent follow-up over approximately nine years showed no significant changes.

Lichen sclerosus is a chronic cutaneous inflammatory condition, which presents with various features such as hyperkeratosis, epidermal atrophy, purpura, hyperpigmentation, and depigmentation to varying degrees. Although sclerosis is a key histopathological finding in the tissue diagnosis, certain cases lack histological evidence of sclerosis or exhibit very subtle sclerosis, a condition termed lichen sclerosus sine sclerosis. In cases like the present one, where widespread melanosis extends to the external genital mucosa without obvious sclerosis, differentiation from early vulvar melanoma in situ can be challenging and perplexing. Repeated biopsies and/or long-term observation aid in definitive diagnosis.

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Eri Katayama, MD