Topical imiquimod immunotherapy in the management of lentigo maligna

Abstract

Melanoma in situ of the lentigo maligna (LM) type is a precursor lesion of LM melanoma. It most commonly occurs in elderly individuals, on the head and neck. Although surgical excision is recommended, this may not be practical for large lesions at cosmetically sensitive sites. In addition, histological changes commonly extend beyond the clinical margins of the lesion. This study describes the use of imiquimod 5% cream as topical immunotherapy in the management of lentigo maligna. Twelve patients (average age 63 years, 10 female), of biopsy-proven facial LM were treated with topical imiquimod, three times a week for 6 weeks. In the absence of an inflammatory response, patients were asked to apply the treatment daily. Seven showed clearance of the LM clinically and histologically. A further three patients showed clearance histologically with persisting pigmentation due to dermal melanin and melanophages. Thus, 10 of 12 patients cleared with no relapse after a median follow-up of 6 months. Two patients failed to respond to imiquimod and their lesions were treated with surgical excision. Imiquimod was well tolerated, except in three patients who experienced an intense inflammatory response. Two of these also developed secondary infection. Imiquimod 5% cream appears to offer a potential noninvasive method for the treatment of lentigo maligna.