Bowenoid papulosis

Clinical features

• Multiple (often 4 to 30+) small (2–10 mm) pigmented brown to violaceous papules with a smooth or velvety surface.
• Distribution: penile shaft and glans (men); vulva, perianal area (women); perianal in both sexes.
• Median age 25–35; both sexes; sexually active patients.
• Usually asymptomatic; occasional itch or soreness.
• Frequently misdiagnosed as warts (condyloma acuminatum), seborrhoeic keratoses, naevi or melanoma.

Differential diagnosis

• Anogenital warts (condyloma acuminatum) — usually verrucous, skin-coloured to white, less pigmented, low-risk HPV (6, 11).
• Vulvar / penile intraepithelial neoplasia (VIN, PeIN) — usually fewer, larger, less pigmented lesions; behaves more aggressively. The histological line between bowenoid papulosis and HPV-driven uVIN/PeIN is blurred — the distinction is largely clinical (multifocal small papules in a young patient = bowenoid papulosis; large solitary plaque in older patient = VIN/PeIN).
• Erythroplasia of Queyrat — solitary or few large red velvety plaque on glans of older uncircumcised man.
• Bowen's disease — solitary scaly plaque on sun-exposed or anogenital skin of older adult.
• Pigmented seborrhoeic keratosis, melanocytic naevus — clinical mimics.

Diagnosis

• Punch biopsy of representative lesion(s).
• Histology indistinguishable from Bowen's disease — full-thickness keratinocyte atypia with mitoses at all levels — but in a multifocal anogenital field of a young adult.
• p16 strongly diffuse positive (HPV-driven); high-risk HPV typing (especially HPV-16) supports diagnosis.
• Examine the entire anogenital area, oral mucosa and assess for cervical disease in women.
• HIV testing in selected patients.

Management

• Conservative — many lesions regress spontaneously over months to years, particularly in young patients with intact immunity.
• Topical 5% imiquimod (3 nights/week for 12–16 weeks) — clearance in 50–80%.
• Topical 5-fluorouracil — alternative.
• Cryotherapy, curettage, electrocautery, CO₂ laser — for selected larger/persistent lesions.
• Surgical excision reserved for atypical, suspicious or refractory lesions.
• Counsel about sexual transmission, condom use and partner examination.
• Cervical cytology and HPV screening for the patient and female partners.
• HPV vaccination — primary prevention for partners and unaffected individuals; may reduce recurrence in treated patients.

Prognosis

Excellent — most cases regress or are cleared with conservative treatment. Progression to invasive squamous cell carcinoma is uncommon in young immunocompetent patients (<5% in older cohorts); modern series including older patients and HIV-positive or otherwise immunocompromised cohorts report progression rates of 10–15%. Long-term surveillance (annual review and prompt biopsy of any persistent or atypical lesion) is appropriate, particularly in immunocompromised patients.