Lentiginous Melanoma In Situ Treatment With Topical Imiquimod: Need for Individualized Regimens

M elanoma in situ, lentiginous type (LM), is a precursor lesion for invasive malignant melanoma, lentiginous type (LMM). Already the most prevalent subtype of in situ melanoma, LM has been shown to be increasing in incidence. Currently, nonsurgical patients with LM have no treatment alternative but irradiation and so must endure the associated adverse effects of this treatment. In addition, recurrence following standard therapies is unacceptably high (8%-20%). For these reasons, a new effective therapy for LM that provides local control, prevents progression to LMM, and decreases morbidity and mortality is clinically desirable. Small studies have reported successful treatment of LM with imiquimod, 5%, cream. The present case series highlights 15 LM lesions in 14 patients treated with topical imiquimod. Histologic tissue specimens obtained before, during, and after treatment were evaluated to assist in directing patient management and in providing objective posttreatment histopathologic response.