We disagree with the conclusions reached by Egan et al1 regarding the malignant nature of the 2 described melanocytic proliferations found in the background of lichen sclerosus et atrophicus (LSA). We believe these proliferations represent vulvar melanocytic nevi with histological features frequently identified in genital skin. Their histological interpretation was further confounded by secondary alterations from the "coincidental" inflammatory dermatosis LSA.
Genital melanocytic nevi, particularly vulvar nevi, show histological features that in other sites could be interpreted as malignant melanoma (MM). Vulvar nevi show pagetoid upward migration of intraepidermal melanocytes in 80% of cases.2 Bridging of junctional nests with the formation of large confluent nests, mild cytologic atypia of intraepidermal melanocytes (enlarged melanocytes with increased cytoplasm), and lateral extension of the junctional component beyond the confines of the dermal melanocytic component are frequent findings in vulvar nevi and are shared with the so-called dysplastic melanocytic nevus; however, these
Carlson JA, Mihm MC. Vulvar Nevi, Lichen Sclerosus et Atrophicus, and Vitiligo. Arch Dermatol. 1997;133(10):1314-1315. doi:10.1001/archderm.1997.03890460140026