Human Papillomavirus Infections

Human Papillomavirus Infections - Viral Villain Intro

• Virus: Human Papillomavirus (HPV)
  • Structure: Double-stranded DNA (dsDNA), non-enveloped.
• Transmission:
  • Direct contact (skin-to-skin).
  • Indirect contact (fomites).
  • Sexual contact.
• Key HPV Types & Associations:
  • Low-risk (cutaneous & genital warts/condyloma acuminata): e.g., 6, 11.
  • High-risk (cancers: cervical, anogenital, oropharyngeal): e.g., 16, 18, 31, 33.
• Pathogenesis:
  • Infects basal keratinocytes of stratified squamous epithelium.
  • Oncogenic potential (high-risk types) linked to viral proteins E6 and E7.

    ⭐ High-risk HPV E6 protein targets p53 (tumor suppressor protein) for degradation, and E7 protein inactivates retinoblastoma protein (pRb).

Human Papillomavirus Infections - Common Wart Parade

• Common cutaneous manifestations of HPV infection, varying by type and location.

⭐ The presence of thrombosed capillaries (black dots) is a characteristic feature of plantar warts (Verruca plantaris).

Human Papillomavirus Infections - Risky Regions

• Anogenital Warts (Condyloma Acuminata)
  • Cauliflower-like lesions.
  • Commonly HPV 6, 11.
  • 
• Koilocytes
  • Pathognomonic cytological feature: perinuclear halo, nuclear atypia (raisinoid nucleus).
• Oncogenic Potential
  • Cancers: Cervical (most common), vulvar, vaginal, penile, anal, oropharyngeal.
  • Primarily HPV 16, 18; also 31, 33, 45.
  • E6 gene product → p53 degradation.
  • E7 gene product → pRb inactivation.
• Laryngeal Papillomatosis
  • Benign tumors in larynx.
  • HPV 6, 11.
  • Common in children (vertical transmission during birth).

⭐ Koilocytic atypia, characterized by a perinuclear vacuole and an irregular, enlarged nucleus, is a histological hallmark of HPV infection.

📌 Mnemonic (Oncogenic HPV types): 16 and 18 can cause Cancer (Cervical).

Human Papillomavirus Infections - Warding Off Warts

• Diagnosis: Primarily clinical.
  • Acetic acid test: Acetowhitening (subclinical genital lesions).
  • Biopsy: If uncertain, unresponsive, or malignancy suspected.
  • HPV DNA tests: Cervical cancer screening, high-risk type ID.
• Treatment Modalities: Choice depends on wart type, location, size, number, patient preference, and immune status.

• Prevention:
  • HPV Vaccines (e.g., Gardasil 9: types 6, 11, 16, 18, 31, 33, 45, 52, 58). Recommended ages for vaccination.
  • Cervical cancer screening (Pap smear, HPV testing).

⭐ Imiquimod is an immunomodulator that acts as a Toll-like receptor 7 (TLR-7) agonist, stimulating innate and cell-mediated immune responses against HPV.

High‑Yield Points - ⚡ Biggest Takeaways

• HPV types 6 & 11 primarily cause anogenital warts (condyloma acuminata).
• HPV types 16 & 18 are high-risk oncogenic types, linked to cervical and other SCCs.
• Koilocytes on microscopy (perinuclear halo, wrinkled nucleus) are pathognomonic.
• Common warts (verruca vulgaris) frequent on hands; plantar warts on soles; flat warts on face.
• Treatment options include topical podophyllin/imiquimod, cryotherapy, and salicylic acid.
• Prophylactic HPV vaccination is crucial for preventing infections with major oncogenic types_