Diagnostic Utility of Acetic Acid-induced Acetowhite Change in Suspected Penile Intraepithelial Neoplasia

Introduction: Penile intraepithelial neoplasia (PeIN) is a premalignant lesion with clinical features that often overlap with benign inflammatory dermatoses. Although biopsy remains the diagnostic gold standard, topical acetic acid application producing an acetowhite reaction is sometimes used to aid clinical assessment. This study evaluated the diagnostic utility of acetic acid-induced acetowhite change in identifying penile dysplasia or PeIN. Methods: A retrospective observational cohort study was conducted at a tertiary penile cancer referral centre. Consecutive patients referred with suspicious erythematous penile lesions between September 2022 and September 2025 who underwent both topical acetic acid application and penile biopsy were included. Acetowhite responses were categorised as negative, mildly positive, or strongly positive based on contemporaneous clinical documentation. Histopathological diagnosis from biopsy specimens served as the reference standard. The association between acetowhite response and histological outcome was assessed using chi-squared analysis. Results: Fifty-two patients were included. Histopathology demonstrated benign findings in 34 patients, PeIN in 10, mild dysplasia in 1, and moderate-severe dysplasia in 7. Acetowhite change was observed across both benign and dysplastic lesions. No significant association was identified between the presence or degree of acetowhite change and histologically confirmed dysplasia or PeIN (p = 0.686). Conclusion: Acetic acid-induced acetowhite change did not reliably predict the presence of penile dysplasia or PeIN. These findings suggest that acetic acid testing has limited diagnostic utility in the assessment of suspicious penile lesions and should not influence decisions regarding biopsy, which remains essential for accurate diagnosis regardless of the response to acetic acid application.