Bowen’s Disease of the Penis
A 65-year-old man presented with an asymptomatic lesion on his penis. The lesion had been present for 6 years and had exhibited no change. He had been previously treated with topical antifungals and topical corticosteroids including ketoconazole cream and desonide ointment without benefit.
Examination revealed discrete erythematous and slightly raised plaques with dry adherent scale located on the glans and shaft of the penis. A biopsy showed squamous cell carcinoma in situ (Bowen’s disease) of the penis. The patient preferred a non-surgical approach and therefore imiquimod 5% cream was used. The cream was applied twice a week for 5 weeks, at which point it was discontinued because some erosions had developed. Three weeks later there was no clinical evidence of residual Bowen’s disease, and no recurrence has been noticed during the next 2 years of follow-up.
Bowen’s disease is a superficial squamous cell carcinoma in which cancer cells are confined to all layers of the epidermis but have not yet invaded the dermis. Bowen’s disease of the penis, also referred to as erythroplasia of Queyrat, is seen almost exclusively in uncircumcised men. The exact etiology is unknown, but several studies have linked this disorder to human papillomavirus infection.1
Aggressive therapy is especially important in genital lesions as this area has a higher rate of invasion and metastasis. Treatment options for Bowen’s disease of the penis include cryotherapy, curettage, laser ablation, surgical excision, and Mohs surgery. However, if a less invasive approach is desired, topical imiquimod 5% cream and 5-fluorouracil are additional options.2,3 These can be used as stand-alone treatment or as an adjunct to other therapies.
Imiquimod is an immune response modulator that acts on the toll-like receptor (TLR) 7. It is thought that TLR-7 induces interferon-α, which enhances Th1 cell-mediated antitumor activity, macrophages, and cytokines.4 Imiquimod is currently FDA approved for the treatment of actinic keratosis, superficial basal cell carcinoma, and genital warts. However, several case series and cohort studies of Bowen’s disease of the penis have achieved an average complete response rate of 70% with no recurrence. Treatment was usually started at 5 times a week and continued for 4 to 6 weeks, but the frequency can be reduced if an adequate inflammatory response is achieved.5,6
Imiquimod can cause significant inflammation as an expected therapeutic response. On the glans penis, a severe inflammatory response may cause edema resulting in urethral obstruction. For this reason, we proceeded cautiously by starting out treatment just twice a week. If there is no significant response after a few weeks, the frequency of application can be increased. ■
References:
1.Rubin MA, Kleter B, Zhou M, et al. Detection and typing of human papillomavirus DNA in penile carcinoma: evidence for multiple independent pathways of penile carcinogenesis. Am J Pathol. 2001;159(4):1211-1218.
2.Shimizu I, Cruz A, Chang KH, Dufresne RG. Treatment of squamous cell carcinoma in situ: a review. Dermatol Surg. 2011;37(10):1394-1411.
3.Taliaferro SJ, Cohen GF. Bowen’s disease of the penis treated with topical imiquimod 5% cream. J Drugs Dermatol. 2008;7(5):483-485.
4.Wenzel J, Uerlich M, Haller O, Bieber T, Tueting T. Enhanced type I interferon signaling and recruitment of chemokine receptor CXCR3-expressing lymphocytes into the skin following treatment with the TLR7-agonist imiquimod. J Cutan Pathol. 2005;32(4):257-262.
5.Mahto M, Nathan M, O’Mahony C. More than a decade on: review of the use of imiquimod in lower anogenital intraepithelial neoplasia. Int J STD AIDS. 2010;21(1):8-16.
6.Shabbir M, Minhas S, Muneer A. Diagnosis and management of premalignant penile lesions. Ther Adv Urol. 2011;3(3):151-158.