Table of Contents
Essential features | Terminology | Epidemiology | Sites | Etiology | Clinical features | Diagnosis | Prognostic factors | Treatment | Clinical images | Microscopic (histologic) description | Microscopic (histologic) images | Virtual slides | Positive stains | Negative stains | Differential diagnosis | Additional referencesCite this page: Strickland S. Squamous intraepithelial lesion (LSIL / HSIL). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/vulvaVIN.html. Accessed December 12th, 2019.
Essential features
- Squamous cell carcinoma precursor lesion of the vulva
- Distinct oncogenic pathway compared to differentiated type vulvar intraepithelial neoplasia (dVIN)
Terminology
- The 2015 International Society for the Study of Vulvovaginal Disease (ISSVD) classifies vulvar squamous intraepithelial lesions as follows:
- Low grade squamous intraepithelial lesion (LSIL) (vulvar LSIL, flat condyloma or HPV effect)
- High grade squamous intraepithelial lesion (HSIL) (vulvar HSIL, VIN usual type)
- Differentiated type VIN (J Low Genit Tract Dis 2016;20:11)
- 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)
Sites
- Labia majora, labia minor and posterior fourchette are most frequent sites
- May also affect clitoris, mons pubis, perineal and perianal areas
Etiology
- Human papillomavirus (HPV) driven process (high risk subtypes HPV 16 and 18 are most common)
Clinical features
- Multifocal and multicentric
- Pruritus, dysuria, pain, ulceration
- 20% asymptomatic but abnormal self examination
- White or erythematous macules or papules
- Can coalesce to form verrucous plaques and can be pigmented
- Multicentric intraepithelial or invasive squamous neoplasia of cervix, vagina or anus in 25 - 66% (J Pediatr Adolesc Gynecol 2004;17:45, Cancer 1995;75:2879, Obstet Gynecol 2006;108:1361, Br J Cancer 2009 Jul;101:27)
Diagnosis
- 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
- Low risk (3 - 5%) of malignant transformation after treatment (Gynecol Oncol 2005;97:645, Obstet Gynecol 2005;106:1319)
- Risk factors for malignant progression include advanced age, radiotherapy and immunosuppression (Gynecol Oncol 1988;31:154)
- Can progress to basaloid or warty squamous cell carcinoma
- Small percentage undergo spontaneous regression (Gynecol Oncol 2005;97:645,Obstet Gynecol 2000;96:470)
- Recurs in 13 - 36% (Cancer 1984;54:1429, Obstet Gynecol 1994;84:741, Gynecol Oncol 1995;56:276, J Reprod Med 1986;31:808)
- Studies are conflicting on if positive surgical margins are a risk factor for recurrence (Gynecol Oncol 2005;97:645, Obstet Gynecol 2005;106:1319, Int J Gynecol Cancer 2002;12:490, Obstet Gynecol 1999;93:633)
Treatment
- Local excision, imiquimod, cidofovir, photodynamic therapy or laser ablation
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
Virtual slides
Positive stains
Negative stains
Differential diagnosis
- Lichen sclerosus
- Squamous cell hyperplasia
- Pseudoepitheliomatous hyperplasia
- Inflammatory / infectious / dermatologic disorders: seborrheic keratosis, psoriasis, lichen planus, spongiotic dermatitis, lichen simplex chronicus
- Differentiated VIN with a basaloid pattern
- Extramammary Paget disease
- Melanoma
- Verrucous carcinoma
Additional references
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