Melanoma
Melanomas are malignant tumors arising from pigment cells: melanocytes. They arise from the neural crest, a transitory embryological structure at the dorsal borders of the neural plate.
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Melanoma Sandra Ronger Savle
41.1 Clinical Presentation Melanomas are malignant tumors arising from pigment cells: melanocytes. They arise from the neural crest, a transitory embryological structure at the dorsal borders of the neural plate. Melanoma is the second most common malignancy of the vulva after squamous cell carcinoma, accounting approximately 10% of vulvar malignancies [1]. Vulvar melanoma accounts for approximately 1.4% of all body melanomas [2]. The Surveillance Epidemiology and End Results database of the US National Cancer Institute noted only 644 cases of vulvar melanoma from 1973 to 2003. The incidence of mucosal melanomas remains stable over the years, in contrast to cutaneous melanoma. It is 0.1 per 100,000 females per year [3]. Its incidence is increasing with age: the median age is 68 years. However, it may be diagnosed at any age with cases reported in girls as young as 10 and women as old as age 99. Malignant melanoma in children has been reported in lichen sclerosus, but it must be noted that junctional and compound nevi may be mistaken for malignant melanoma when they are superimposed on lichen sclerosus in children and adolescents [4]. There are six cases of melanoma on girls [5]. S. Ronger Savle (*) Department of Dermatology and Gynecology, Lyon 1 University and Centre Hospitalier Lyon Sud, Lyon, France
Family history of melanoma is noted in 15% of cases. Women are generally Caucasian and in the fifth to eighth decades of life. Compared with cutaneous melanoma, it has less marked difference in incidence across racial ethnic groups. Risk factors for development have not been identified. HPV, HSV, and polyomavirus have no role in the ethiopathogenesis. Unlike most cutaneous melanoma, ultraviolet radiation doses do not appear to play a role in the pathogenesis of vulvar melanoma. The etiology of vulvar melanoma is complex and multifactorial. From molecular genetic perspective, it more closely resembles acral lentiginous rather than cutaneous melanoma. KIT is the most commonly mutated gene found with sequence variants detected in up to 35% of vulvar melanomas [6]. More rarely, NRAS and BRAF mutations have been described [7]. Melanoma has high levels of chromosomal instability, with many copy number aberrations when comparing with Atypical melanocytic nevi of genital type (AMNGT) [8]. Chronic inflammation such as lichen sclerosus has been linked to vulvar melanoma, but this association is controversial [9]. Melanoma arises mainly in the clitoral area and labia majora, followed by labia minora and periurethral area. Sometimes a multifocal origin is observed. It may present as macules, papules, or nodules of irregular coloration, asymmetric borders, and diameter larger than 7 mm [10] (Fig. 41.1).
© Springer International Publishing AG, part of Springer Nature 2019 J. Bornstein (ed.), Vulvar Disease, https://doi.org/10.1007/978-3-319-61621-6_41
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Fig. 41.2 Melanoma in situ of the left labia minora
Fig. 41.1 Nodular melanoma. The prognosis is poor but the diagnos
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