Epidermodysplasia Verruciformis

Clinical and Pathological Features

Genetic Cause and Pathogenesis

• Key gene mutations (EVER1/TMC6 and EVER2/TMC8):
  • Most cases of EV are inherited in an autosomal recessive pattern. Homozygous or compound heterozygous mutations in EVER1 or EVER2 (on chromosome 17q25) are the leading cause.
  • Mechanism: The EVER1 and EVER2 proteins form a complex with the zinc transporter ZnT1 in the endoplasmic reticulum to regulate intracellular zinc (Zn²⁺). Without this complex, cells lose the ability to suppress HPV transcription factors, allowing the virus to replicate freely in keratinocytes.
• Selective cell-mediated immune defect: Antibody (humoral) responses are normal, but the T-cell-mediated response against EV-HPV types is defective.
• EV-HPV types:
  • HPV types characteristic of the disease: HPV-5, 8, 9, 12, 14, 15, 17, 19–25, 36, 38, 47 and 50.
  • Of these, HPV-5 and HPV-8 have the highest oncogenic potential and are found in more than 90% of cSCCs in EV patients.
• Acquired EV: Occurs in people with severe immunosuppression, such as HIV/AIDS, organ transplant recipients or those on long-term immunosuppressive drugs.

Clinical Features

Skin lesions usually begin in childhood (ages 5–11), with two types often seen together:

• Flat wart-like lesions (verruca plana-like):
  • Flat, slightly raised papules with a smooth or faintly velvety surface, pink-red, skin-colored or pale gray (2–6 mm).
  • Concentrated on the backs of the hands, forearms, face and neck.
• Tinea versicolor-like lesions (pityriasis versicolor-like):
  • Light brown, café-au-lait or pinkish-gray hypopigmented patches covered with fine scale.
  • Found mainly on the trunk (chest, back, abdomen) and lower legs.
• Malignant transformation:
  • Begins at ages 30–50 on chronically sun-exposed skin (face, forehead, neck, backs of the hands).
  • EV papules and plaques progress to actinic keratosis (AK) > Bowen disease (cSCC in situ) > invasive cSCC, or to basal cell carcinoma (BCC).

Histopathology

• Hyperkeratosis and acanthosis: Mildly thickened stratum corneum and a hyperplastic epidermis.
• Distinctive blue-gray keratinocytes (pathognomonic EV cells):
  • The spinous and granular layers contain swollen keratinocytes with abundant, characteristically pale blue-gray cytoplasm.
  • Nuclei are enlarged and slightly hyperchromatic with irregular outlines, and there are many abnormal keratohyalin granule clumps.
• No marked inflammatory infiltrate: Only a light lymphocytic infiltrate in the upper dermis, reflecting the lack of an immune response to clear the virus.

Differential Diagnosis and Immunohistochemistry (IHC)

Our Approach to EV

At Haute-Derma, our EV management rests on strict prevention and conservative intervention:

• Rigorous photoprotection: Because sunlight (UV) is the key trigger that turns EV lesions into squamous cell carcinoma, strict sun protection from childhood is vital.
• Regular cancer screening with skin mapping and dermoscopy: Each papule and patch on exposed skin is monitored so that any sign of malignant change is caught as early as possible.
• Avoiding destructive treatment of benign lesions: Because EV lesions cover the whole body, it is neither possible nor advisable to burn or cut out every benign papule. Treatment focuses on lesions that have become precancerous or cancerous.

How We Diagnose Epidermodysplasia Verruciformis at Haute-Derma

• Clinical exam and family history: We note widespread flat wart-like or tinea versicolor-like lesions present since childhood and ask about parental consanguinity or relatives with similar lesions.
• High-resolution dermoscopy:
  • Benign EV lesions: a brown-gray pseudo-network and small, evenly spaced dotted vessels on a pink background.
  • Signs of malignant change: thick scale, a strawberry pattern, irregular glomerular vessels, or areas of ulceration or firm infiltration.
• Skin biopsy (punch biopsy):
  • Essential to confirm the diagnosis by finding keratinocytes with pale blue-gray cytoplasm.
  • Any lesion on exposed skin that looks suspicious for cancer is biopsied as part of ongoing follow-up.
• HPV typing by PCR and gene sequencing: Confirms high-risk HPV-5/8 and screens for EVER1/EVER2 mutations.

Specialized Treatment Options at Haute-Derma

There is currently no cure for the underlying genetic defect in EV, so treatment focuses on controlling lesions and preventing skin cancer:

• Comprehensive UV protection: Broad-spectrum sunscreen (UVA/UVB, SPF 50+, PA++++), sun-protective clothing, and strict avoidance of sun exposure between 10 a.m. and 4 p.m.
• Systemic retinoids:
  • Acitretin / isotretinoin: Oral retinoids normalize keratinocyte differentiation, flatten lesions and suppress the growth of malignant tumors. Low-dose maintenance is used in severe cases.
• Topical immunomodulating therapy:
  • Imiquimod 5% cream: Triggers local interferon production to help control viral replication.
  • Topical cidofovir: An antiviral that helps reduce HPV load.
• Destructive treatment for precancerous and cancerous lesions:
  • Ultrapulsed CO2 laser / Mohs surgery: For actinic keratoses, Bowen disease or squamous cell carcinoma (cSCC) arising in EV.
  • Photodynamic therapy (PDT): Clears widespread precancerous lesions on the face and neck.