Objective: This study aimed to investigate the optimal depth of vulvar intraepithelial neoplasia (VIN) and involved skin appendages to provide evidence for treatment.
Methods: The study retrospectively enrolled and analyzed the clinical characteristics of all VINs in the obstetrics and gynecology department of a university hospital from January 1, 2019, to December 30, 2021. The study further explored the thickness of epithelium and skin appendages of 285 women with low-grade VIN (VIN 1) and 285 women with high-grade VIN (VIN 2/3).
Results: The study included 1,474 VINs: 1,139 (80%) VIN 1 and 335 (20%) VIN 2/3 cases. The VIN 1 and VIN 2/3 groups showed a significant difference in HPV infection (P<0.01) but not in cytology (P=0.499). The majority (89.90%, 1,325) of the cases occurred in one area of the vulva, whereas 10.11% had multifocal areas. VIN commonly occurred on the posterior fourchette (76.85%), labia majora (11.61%), and labia minora (9.92%). The VIN 2/3 groupreported a significantly higher positive rate for concurrent Cervical and Vaginal intraepithelial neoplasia (160 of 285) compared with the VIN 1 group (321 of 953) (P=0.000). The involved epithelial thicknesses in VIN 2/3 and VIN 1 were 0.69±0.44 and 0.49±0.23 mm, respectively, both greater than their noninvolved epithelial thickness (0.31±0.19 and 0.32±0.10 mm, p<0.001 and p<0.001, respectively). In circumstances of appendage involvement, VIN thickness was 1.98±0.64 mm.
Conclusions: VIN thickness was generally ≤1 mm for the superficial lesions in non-hairy areas. Lesions extending onto hairy areas were about 3 mm, destroying involved skin appendages.