CPC11 A case of vulval melanosis and depigmentation

Abstract A 51-year-old lady was referred to the vulval clinic with new vulval pigmentation. She had a 20-year history of lichen sclerosus (LS), which she managed with clobetasol propionate ointment. She was perimenopausal, for which she had a hormone replacement therapy patch. On examination she had pigmentation at the superior aspect of the right labium minus and clitoral hood and a small pigmented papule on the left labium minus. There was also depigmentation on the right inferior labium minus and hyperkeratosis and depigmentation to the left labium minus. There was perianal depigmentation. Our clinical impression was of vulval melanosis, LS and possible coexisting vitiligo. Three 4-mm punch biopsies were required to confirm the diagnoses and rule out melanoma with regression. The first biopsy was taken from a pigmented patch on the right superior labium minus. Histological findings were of pigmentation more prominent towards the tips of the rete ridges. There were scattered melanophages in the superficial dermis and a mild chronic lymphocytic infiltrate. SOX10 immunohistochemistry (IH) showed normal density of cytologically bland basally orientated intraepidermal melanocytes, in keeping with melanosis and postinflammatory hyperpigmentation. The second biopsy, taken from hyperkeratosis on the right inferior labium minus, showed hyperkeratosis overlying a thin epidermis lacking any basal-layer pigmentation. There were no melanophages or inflammation. SOX10 IH showed complete absence of intraepidermal melanocytes, diagnostic of vitiligo. The third biopsy was taken from a pigmented papule within a depigmented patch on the left labium minus. In one half of the biopsy there was prominent homogenization of superficial dermal collagen, whereas in the other half were fairly numerous dermal melanophages. SOX10 IH showed almost complete absence of intraepidermal melanocytes in the first half of the biopsy, but normal numbers in the second half. Therefore the first half showed well-developed features of LS with overlying vitiligo, while the other half showed melanosis and postinflammatory hyperpigmentation. There was no evidence of dysplasia or malignancy in any of the biopsies. LS and vitiligo are both chronic autoimmune inflammatory dermatoses that can cause anogenital pigment loss. Overlap of these conditions affecting the vulva has been described in a case series of peri- and postmenopausal women and also in children. Vulval pigmentation presents a diagnostic challenge, as the features of vulval melanosis can overlap with those of melanoma. This unusual case of a patient with LS, vitiligo and vulval melanosis highlights the importance of taking multiple biopsies in vulval conditions with variable pigmentation to ensure accurate clinicopathological correlation.