A 32-year-old woman undergoes cervical screening as part of routine health check-up in a tertiary centre in Delhi. Pap smear shows atypical squamous cells of undetermined significance (ASCUS). HPV testing is positive. Which is the most common HPV type associated with cervical intraepithelial neoplasia (CIN)?

Explanation

## HPV Types and CIN Risk Stratification **Key Point:** HPV-16 is the most common high-risk HPV type associated with CIN and cervical cancer, accounting for approximately 50–60% of all cervical cancers and a significant proportion of CIN lesions. ### HPV Classification by Oncogenic Potential | HPV Type | Risk Category | Association with CIN/Cancer | Prevalence in Lesions | |----------|---------------|----------------------------|----------------------| | HPV-16 | High-risk | Most common in CIN-2/3 and invasive cancer | 50–60% of cancers | | HPV-18 | High-risk | Associated with adenocarcinoma | 15–20% of cancers | | HPV-31, 33, 45 | High-risk | Less common than HPV-16/18 | 5–10% combined | | HPV-6, 11 | Low-risk | Benign warts, minimal CIN risk | <1% of cancers | **High-Yield:** HPV-16 and HPV-18 together account for ~70% of cervical cancers. HPV-16 is the single most oncogenic type and the strongest predictor of progression from CIN-1 to CIN-3. ### Clinical Significance **Clinical Pearl:** In a woman with ASCUS and positive HPV, HPV-16 positivity carries the highest risk of underlying CIN-2/3 or cancer and warrants immediate colposcopy and biopsy, whereas HPV-18 and other high-risk types also require colposcopy but may have slightly lower immediate progression risk. **Mnemonic:** **HR-HPV (High-Risk)** = 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68. Of these, **HPV-16 is #1** in frequency and oncogenic potential. **Warning:** Do not confuse HPV-6 and HPV-11 (low-risk types causing benign genital warts) with high-risk types. These are NOT associated with CIN progression. [cite:Park 26e Ch 3]