Eruptive keratoacanthoma and squamous cell carcinoma complicating imiquimod therapy: response to oral acitretin.

An 87-year-old woman with eruptive keratoacanthomas complicating recent imiquimod therapy is presented. Lesions developed both at and distal to the treatment site. She responded well to 8 weeks of oral acitretin with resolution of most lesions and no recurrence at 6 months post treatment. A remaining lesion was excised and found to be a well-differentiated squamous cell carcinoma. Keratoacanthoma and squamous cell carcinoma should be considered in any patient developing rapidly growing keratotic nodules in association with recent imiquimod therapy. The aetiology and treatment of eruptive keratoacanthomas is briefly discussed.