Penile intraepithelial neoplasia

What is penile intraepithelial neoplasia?

Penile intraepithelial neoplasia is a rare pre-cancerous disease of the outer skin layer (epidermis) of the penis.

Other names for penile intraepithelial neoplasia include:

• Squamous intraepithelial lesion
• Erythroplasia of Queyrat
• Bowen disease of the penis
• In-situ squamous cell carcinoma of the penis
• PIN.

How is penile intraepithelial neoplasia recognised?

The diagnosis is often delayed, because penile intraepithelial neoplasia may resemble other conditions such as balanitis, candidiasis, dermatitis, and psoriasis.

Lesions are single or multiple, red plaques on the glans or inner aspect of the foreskin. They may have a smooth, velvety, moist, scaly, eroded, or warty surface.

The following signs and symptoms may occur:

• Redness and inflammation
• Itching
• Crusting or scaling
• Pain
• Ulcers
• Bleeding
• In the late stages, discharge from the penis, difficulty pulling back foreskin, or difficulty passing urine

Images of penile intraepithelial neoplasia

Who is at risk of penile intraepithelial neoplasia and what causes it?

Uncircumcised males over 50 years of age are most at risk of getting penile intraepithelial neoplasia, although it may rarely occur in younger men.

Penile intraepithelial neoplasia is associated with:

• Chronic infection with high-risk human papillomavirus (HPV) types. HPV-16 is the most common type identified [see Sexually acquired human papillomavirus]
• Chronic skin disease, especially lichen sclerosus and lichen planus
• Smoking
• Immune suppression by medications or disease
• Chronic irritation by urine, friction or injury to the penile area.

If left untreated, 10–30% of cases develop into invasive squamous cell carcinoma (cancer) of the penis.

What is the treatment for penile intraepithelial neoplasia?

Skin biopsy should be performed to confirm the diagnosis, as it may resemble other forms of chronic balanitis. A biopsy is also essential to rule out invasive squamous cell carcinoma, which requires more aggressive treatment.

It is important to maintain good genital hygiene. Penile intraepithelial neoplasia can be treated in several different ways. Multidisciplinary care may be necessary.

• 5-fluorouracil cream
• Imiquimod cream
• Cryotherapy
• Curettage and cautery
• Laser vaporisation
• Photodynamic therapy
• Radiotherapy
• Excision
• Interferon alpha

Mohs micrographic surgery appears to be highly effective and the surgical treatment of choice in severe or recurrent cases of penile intraepithelial neoplasia.

The disease recurs in 3–10% of patients, so close follow-up is necessary to ensure a complete cure.

Partners of patients with penile intraepithelial neoplasia should be screened for other forms of intraepithelial neoplasia caused by human papillomavirus in the anogenital area (cervical, vulval and anal cancer).

Many national immunisation programmes now include a vaccine against the causative human papillomaviruses HPV-16 and 18. Vaccination of boys and young men should be included, to reduce the risk of developing HPV-related penile intraepithelial cancer in the future. Men with penile intraepithelial neoplasia are sometimes treated with HPV vaccination; its efficacy in this situation is unknown.