Introduction Bowenoid papulosis is a form of penile intraepithelial neoplasia associated with the oncogenic human papilloma virus (HPV) strains 16, 18, 31 and 33. It occurs in young sexually active patients and has a low risk of progressing to invasive squamous cell carcinoma.

Case report The patient was a 31 year old chinese male who presented with a 3 month pruritic rash over his glans penis. Previous treatment with hydrocortisone cream had caused more lesions to appear and was stopped.

On examination, there were multiple erythematous discrete papules over the glans penis and a cluster of papules at the inner prepuce. A skin biopsy was consistent with bowenoid papulosis showing a thickened epidermis with full thickness atypical keratinocytes with loss of normal polarity. A band like infiltrate of lymphocytes, plasma cells and eosinophils was present within the dermis. The rest of his sexually transmitted infection screen including syphilis serology and human immunodeficiency virus tests were negative.

He was started on topical imiquimod three applications per week and noted complete clearance of the prepuce lesions after two weeks, with flattening of the lesions on the glans. All lesions were noted by the patient to have cleared after four weeks of imiquimod use, and only post inflammatory hyperpigmentation was noted at his review after six weeks. Minimal side effects were noted by the patient except for transient itch.

Discussion We report our first case of penile bowenoid papulosis responding to imiquimod monotherapy, and is the 5th reported case to date. Our case demonstrates one of the most rapid clinical clearance within six weeks, after only four weeks of imiquimod application. Other treatment modalities like electrocurrettage, 5-fluorouracil or topical interferon have all been associated with recurrence. Immunomodulatory treatment for this condition appears safe and efficacious, with the added convenience of being patient administered.