A squamous intraepithelial lesion (SIL) is a human papillomavirus (HPV)-associated precancerous squamous epithelial cell lesion of the lower genital tract. [1] SIL is an umbrella term that encompasses intraepithelial lesions that occur at various anatomic locations, such as the cervix, vagina, vulva, or anus. According to the College of American Pathologists (CAP) and the American Society for Colposcopy and Cervical Pathology (ASCCP), these lesions can be classified as either low-grade squamous intraepithelial lesions (LSIL) or high-grade squamous intraepithelial lesions (HSIL). [2] The Bethesda system, an established system for reporting cervical and vaginal cytology, uses HSIL and LSIL to categorize cytologic abnormalities found on the cervix. [3]
Squamous intraepithelial lesions are a cytologic interpretation most commonly identified on Pap smear for cervical cancer screening. A finding of SIL warrants further evaluation to establish a histologic diagnosis. [4] Additional procedures, such as a colposcopy or biopsy of the cervix, vagina, or vulva, may be performed to confirm the diagnosis. [5]
