Vulva & female urethra
Squamous tumors and precursors
Squamous intraepithelial lesion (LSIL / HSIL)

Topic Completed: 1 August 2016

Revised: 10 October 2019

Copyright: 2003-2019,, Inc.

PubMed Search: Usual type vulvar intraepithelial neoplasia

Sarah Strickland, M.D.
Page views in 2019: 8,926
Page views in 2020 to date: 465
Cite this page: Strickland S. Squamous intraepithelial lesion (LSIL / HSIL). website. Accessed January 24th, 2020.
Essential features
  • Squamous cell carcinoma precursor lesion of the vulva
  • Distinct oncogenic pathway compared to differentiated type vulvar intraepithelial neoplasia (dVIN)
  • The 2015 International Society for the Study of Vulvovaginal Disease (ISSVD) classifies vulvar squamous intraepithelial lesions as follows:

  • The 2014 World Health Organization Classification of Tumors of the Vulva classification is as follows:
    • Low grade squamous intraepithelial lesion (LSIL)
    • High grade squamous intraepithelial lesion (HSIL)
    • Differentiated type VIN
  • Epidemiology
    • Younger women (30 - 50 years)
    • Risk factors include HPV infection, smoking, immunosuppression, history of genital herpes and increased number of sexual partners
    • Rate has increased over the last three decades while rate of vulvar squamous cell carcinoma has stayed relatively stable (J Reprod Med 2000;45:613, Obstet Gynecol 2006;107:1018)
    • Labia majora, labia minor and posterior fourchette are most frequent sites
    • May also affect clitoris, mons pubis, perineal and perianal areas
    • Human papillomavirus (HPV) driven process (high risk subtypes HPV 16 and 18 are most common)
    Clinical features
    • Vulvar biopsy: optimally a punch or small incisional biopsy taken from the edge of the lesion including a small piece of normal tissue (Crit Rev Oncol Hematol 2008;68:131)
    Prognostic factors
    • Local excision, imiquimod, cidofovir, photodynamic therapy or laser ablation
    Clinical images

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    Various images

    Microscopic (histologic) description
    • Hyperkeratosis and parakeratosis
    • Acanthosis with club shaped rete ridges
    • Disorientation of the cells above the basal cell layer with variable extension to the surface
    • Nuclear clumping with mitotic figures
    • Intact basement membrane
    • Variable extension into skin appendages
    Microscopic (histologic) images

    Images hosted on other servers:
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    Vulvar Intraepithelial Neoplasia III

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    VIN III H&E stains

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    Vulvar epithelium

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    uVIN 3 basaloid type

    Solitary usual VIN lesion

    Virtual slides

    Images hosted on other servers:
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    Vulvar intraepithelial neoplasia, usual type,
    with low grade dysplasia (VIN 1)

    Positive stains
    • p16: diffuse, strong, cytoplasmic and nuclear band-like pattern
    • Ki67: extends into upper two thirds of the epithelium
    Negative stains
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