Vulva, vagina & female urethra
Melanocytic lesions
Dysplastic nevi
Author: Sarah Strickland, M.D.
Last author update: 1 August 2016
Last staff update: 6 September 2023 (update in progress)
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Dysplastic nevi [title]
Table of Contents
Essential features | Terminology | Epidemiology | Sites | Clinical features | Diagnosis | Prognostic factors | Case reports | Treatment | Clinical images | Microscopic (histologic) description | Microscopic (histologic) images | Virtual slides | Positive stains | Differential diagnosis | Additional referencesCite this page: Strickland S. Dysplastic nevi. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/vulvadysplasticnevi.html. Accessed September 26th, 2023.
Essential features
- Sporadic or part of dysplastic nevus syndrome
- Phenotypic marker of patients at increased risk of melanoma
- Individual nevi rarely progress to melanoma (Histopathology 2010;56:112, Arch Dermatol 2003;139:282)
Terminology
- Also called atypical nevus, nevus with architectural disorder, Clark nevus
Epidemiology
- Relatively rare at genital sites compared to other melanocytic lesions (J Cutan Pathol 1987;14:87)
- Typically becomes clinically apparent at puberty and more predominant in people younger than 30 - 40 years; however can occur at any age
- Can have eruptive dysplastic nevi in organ transplant adults or children following completion of chemotherapy and in HIV+ patients (Hautarzt 2002;53:524, An Pediatr (Barc) 2006;65:260, Dermatology 2002;205:174, Arch Dermatol 1989;125:397)
Sites
- Any site; no predilection for anogenital skin
- At sites with minimal sun exposure (breast, buttocks) and sun exposed areas
- Genital lesions arise mainly on labia majora, labia minora, clitoris
- May occur on perineum, pubic region, male genitalia
Clinical features
- Dysplastic nevus is a histopathologic term
- The following features have been described in dysplastic nevi (Arch Dermatol 1978;114:732, JAMA 1997;277:1439, Med J Aust 1997;167:191):
- > 5 mm in diameter
- Flat or containing a flat component
- Variable, irregular pigmentation
- Irregular or asymmetric outline
- Indistinct borders
- Clinically common nevi (< 5mm, uniformly pigmented, symmetric, distinct margins) often have 1 - 2 histologic features of dysplastic nevi (J Am Acad Dermatol 1990;22:275)
- Poor correlation between clinical atypia and histologic dysplasia (J Am Acad Dermatol 2001;45:77)
Diagnosis
- Biopsy / excision and histological examination
Prognostic factors
- Melanoma risk is higher for persons with dysplastic nevi having higher grades of atypia (Mod Pathol 2003;16:764, J Am Acad Dermatol 1990;22:727)
Case reports
- Three patients (21, 27 and 30 years) with dysplastic genital nevi (Obstet Gynecol 1991;78:968)
Treatment
- Excision
Clinical images
Images hosted on other servers:
Examples of dysplastic nevi
defined based on clinical criteria
Microscopic (histologic) description
- Basilar proliferation of atypical melanocytes which must extend at least three rete ridges beyond the dermal component
- Lentiginous or epithelioid cell pattern proliferation
- Elongation and bridging of the rete ridges
- Variable cellular atypia
- Concentric eosinophilic or lamellar fibroplasia
- Lymphocytic infiltrate
- Vascular ectasia
Microscopic (histologic) images
Images hosted on other servers:
Low magnification micrograph of a dysplastic nevus
Intermediate magnification micrograph of a dysplastic nevus
High magnification micrograph of a dysplastic nevus
Virtual slides
Images hosted on other servers:
Dysplastic nevus
with severe superficial
melanoma
Dysplastic nevus
with slight cytologic
atypia
Dysplastic nevus
with inflammation
and regression
Positive stains
- Ki67 is higher in dysplastic nevi than common nevi (Appl Immunohistochem Mol Morphol 2007;15:160)
Differential diagnosis
- Atypical melanocytic nevus of genital type:
- Large, variably sized juncional nests with prominent retraction artifact or cellular dyscohesion
- Nondescript pattern of dermal fibrosis
- Underlying “mushroom shaped” dermal component with maturation
- Melanoma:
- Asymmetric
- Irregular thickening and thinning of the epidermis
- Uniform cytologic atypia
- Increased pigment incontinence
- Lack of maturation of cells in the dermis
- Dermal mitotic figures
- Pagetoid proliferation of melanocytes
Additional references
