Perianal genital warts

Last revised by Joshua Yap on 12 May 2023

Perianal genital warts, also known as condyloma acuminata (singular: condyloma acuminatum), are a complication of human papillomavirus (HPV) infection. They are diagnosed clinically and are usually painless and benign, but can rarely undergo malignant transformation into squamous cell carcinoma.

70% of cases of genital warts occur in people aged between 20-39 years old 3.

  • other sexually transmitted infections: e.g. chlamydia, gonorrhea

  • high number of sexual partners, especially for men who have sex with men

  • HIV

  • smoking

Genital warts are a clinical diagnosis. In unclear scenarios (e.g. large lesions), PCR genetic testing of samples can confirm the diagnosis. Histological analysis of biopsies can help differentiate these from other anogenital lesions.

Genital warts are usually painless lesions that occur in the anogenital region, but can occur orally and on the hands and feet. Rarely, they can present with bleeding, pain, and pruritus.  

Genital warts are caused by human papillomavirus (HPV) infection, which is the most common STI in the world affecting up to 13% of the human population 1. 40 strains of HPV are known to affect the anorectal regions. Strains 6 and 11 most commonly cause genital warts 2, whereas strains 16 and 18 are at high risk of developing malignancy.

Their appearance can vary but they are usually raised, thickened epithelial lesions that can be sessile, plaque-like, pedunculated, and rarely cauliflower shaped when malignant 5

The affected tissue displays hyperkeratosis and acanthosis. Genital warts have distinctive cells called koilocytes.  

Imaging is an ancillary tool used in cases of large genital warts that may be hard to differentiate from more sinister lesions and mimics on clinical assessment alone. Ultimately, histopathology will clarify the matter.

In malignant transformation, CT can be used to determine the presence of distant metastases.

In cases of large lesions, MRI may aid in identifying the extent of involvement of adjacent structures. Involvement of the anal sphincter may alter the surgical approach 6.  

In malignant transformation, lymphoscintigraphy can be used to determine sentinel lymph node involvement.

Uncomplicated genital warts often resolve spontaneously. For those struggling with the aesthetic and psychological impacts of warts topical ointments such as Imiquimod and Podophyllotoxin can speed recovery 2.

For refractive warts, cryotherapy and surgical excision can be undertaken.

Surgery is the mainstay for warts that have undergone malignant transformation but have not metastasized 7. If there is metastasis, palliative systemic chemoradiotherapy can be given 8.

Rates of recurrence are high, especially for warts that have undergone malignant transformation, as getting clear resection margins is difficult 6

A rare malignant complication of anorectal genital warts is verrucous carcinoma of the anus, also known as giant condyloma acuminatum or Buschke-Löwenstein tumor. This is a type of squamous cell carcinoma. 

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