Melanocytic Nevus
A common nevus represents only 2.3% of clinically pigmented vulvar lesions [1].
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Sandra Ronger Savle
36.1 Clinical Presentation 36.1.1 Common Nevus A common nevus represents only 2.3% of clinically pigmented vulvar lesions [1]. They are more likely noted in young patients, especially in premenopausal women. Common nevi appear at age of 28–33 years, whereas atypical melanocytic nevus of genital type (AMNGT) at the age of 17–26 years. Common nevi are asymptomatic and discovered incidentally during routine physical examination or self-examination. They present as symmetric macules or papules, ranging in color from pink to dark brown, black, or rarely blue. They are well-defined lesions, usually single, round to oval, and basically monochromatic. They can be acquired [2]. Their diameter is typically less than 1 cm (Figs. 36.1 and 36.2). They are often located on the labia majora, labia minora, and clitoral hood. Most vulvar nevi are compound or intradermal nevi, but other variants such as congenital, dysplastic, blue, and Spitz nevi have rarely been reported [2]. Nevus can appear on lesions with lichen sclerosus, making the diagnosis difficult [3].
S. Ronger Savle (*) Department of Dermatology and Gynecology, Lyon 1 University and Centre Hospitalier Lyon Sud, Pierre Bénite, Lyon, France
Sometimes a nevus could be asymmetric, with irregular colors. ABCDE criteria can’t be applied on mucosal areas like on cutaneous lesions (Fig. 36.3).
36.1.2 Atypical Melanocytic Nevus of Genital Type (AMNGT) An uncommon but distinctive melanocytic lesion presenting in the genital area of premenopausal women was first reported by Friedman and Ackerman in 1981. To reflect the often-worrying histologic features, which can suggest a diagnosis of melanoma, the term atypical melanocytic nevus of genital type was proposed by Clark et al. in 1998; this is frequently abbreviated to atypical genital nevus (AGN) [4]. AMNGT may be regarded as a melanocytic nevus with site- specific features and atypia similar to atypical acral nevi, flexural nevi, nevi from the breast, or conjunctival nevi. The precise incidence of AGN is unclear, but it represents approximately 10% of all pigmented lesions and 5% of melanocytic nevi in the genital area [5]. It is most often found in the vulva of premenopausal women, and more than 50% of patients are younger than 20 years. Moreover, a personal or familial history of dysplastic nevi or melanoma may be found at increased rates in patients with AMNGT.
© Springer International Publishing AG, part of Springer Nature 2019 J. Bornstein (ed.), Vulvar Disease, https://doi.org/10.1007/978-3-319-61621-6_36
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Fig. 36.1 (a) Intradermal nevus on the left labia majora. (b) The dermoscopy shows a globular pattern
The clinical appearances are often atypical, with hyperpigmentation and increased lesion size of up to 2 cm in diameter (median, 5.9 mm). It may present as a macule or a papule. They are often black, with different colors. The ABCDE criteria can’t be applied because they may be positive on melanoma lesions, and on AMNGT, and on a nevus. They are lo
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