A two‐stage treatment of lentigo maligna using ablative laser therapy followed by imiquimod: excellent cosmesis, but frequent recurrences on the nose

DEAR EDITOR, Lentigo maligna is the most common subtype of melanoma in situ, with a rapidly growing incidence. It typically arises in chronically sun-exposed skin of elderly individuals. Estimates of the lifetime risk of lentigo maligna progressing to lentigo maligna melanoma vary from 2 2% to 4 7%. The primary treatment goal is complete eradication of the lesion with prevention of recurrences. Surgical excision is the recommended treatment. As lentigo maligna occurs mainly in the head and neck region, important secondary goals are to minimize functional and cosmetic deformities. In large facial lesions or in elderly patients, alternative nonsurgical treatments, or even a wait-and-see policy, may be considered. Our department has introduced a novel treatment combination of ablative laser therapy followed by 6 weeks of topical imiquimod 5% application. Lentigo maligna lesions were first treated with ablative laser therapy with margins of 2–3 cm of adjacent skin to remove the large bulk of atypical melanocytes. The epidermis and superficial papillary dermis were ablated with either 2940-nm erbium-doped yttrium aluminium garnet laser or 10 600-nm CO2 laser. End points of the laser treatment were complete pigment clearance and visible punctuate bleeding. After laser treatment, patients started daily application of imiquimod 5% cream on the erosive skin for 5 days a week for 6 weeks. This topical Toll-like receptor 7 and 8 agonist induced an inflammatory immune response to clear any residual atypical melanocytes. The degree of inflammation was assessed at regular intervals, and depending on the local inflammatory reaction the frequency was increased to twice daily, or reduced to 3 days a week. Potential flu-like symptoms caused by imiquimod were counteracted by 1 g of paracetamol 1–2 h before and 6–8 h after application of imiquimod cream. In our previous publication we reported the absence of recurrences in 12 patients after a mean follow-up of 22 months, with good-to-excellent cosmetic results. We have now reviewed 35 patients who were treated in a similar fashion and present the recurrence rates and patient satisfaction of this cohort, including the long-term follow-up results of the original cohort. All patients with histologically proven lentigo maligna, who had undergone ablative laser therapy followed by imiquimod, between 2008 and 2014, were retrospectively identified. Data collected included age, sex, anatomical site of the lesion, histopathological results, treatment details (laser device, duration and dosing regimen of imiquimod cream), follow-up