Pathology Lecture 3: Epithelial Pathology I

Benign HPV-related Lesions

• Human papillomavirus (HPV) is a double-stranded DNA virus that infects skin or mucosa, exhibiting tropism for squamous epithelium.
• There are over 130 HPV types, with more than 30 types known to infect the oral mucosa.
• Most infected individuals are asymptomatic and lack clinically evident disease.

Low-Risk HPV Types

• HPV types 6, 11, 13, 32, 40, 42, 43, 44, 54, 55, 61, 62, 64, 67, 69, 70, 71, 72, and 81 are considered low-risk.

High-Risk HPV Types

• HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68, and 73 are associated with malignant transformation.

HPV Vaccines

• Quadrivalent vaccine (Gardasil) targets HPV types 6, 11, 16, and 18.
• Bivalent vaccine (Cervarix) targets HPV types 16 and 18.

Oral HPV Infection

• Oral HPV infection is present in approximately 5% to 12% of normal, healthy individuals.

Pathogenesis of HPV

• In normal-appearing skin or mucosa, the virus may remain in a latent state within the nuclei of basal epithelial cells in low numbers.
• In lesional epithelium, the virus is present in increased copy numbers within various epithelial cell layers.

Squamous Papilloma

• Squamous papilloma is a benign papillary or verruciform mass resulting from HPV-induced proliferation of stratified squamous epithelium.
• HPV types 6 and 11 are associated with low virulence and infectivity rate, accounting for 3% of all oral lesions.
• Clinical features include:
  • Soft, painless, usually pedunculated, exophytic nodule with numerous fingerlike surface projections.
  • White, slightly red, or normal in color, depending on the amount of surface keratinization.
  • Typically solitary, with a maximum size of about 0.5 cm, with little or no change thereafter.
• Histopathologic features include:
  • Proliferation of keratinized stratified squamous epithelium arranged in fingerlike projections with fibrovascular connective tissue cores.
  • Keratin layer is thickened in lesions with a white clinical appearance, and the epithelium typically exhibits a normal maturation pattern.
• Treatment and prognosis:
  • Conservative surgical excision is recommended.
  • No reported malignant transformation, continuous enlargement, or dissemination to other parts of the oral cavity.

Verruca Vulgaris (Common Wart)

• Verruca Vulgaris is a focal, benign, HPV-induced hyperplasia of stratified squamous epithelium.