Change in lentigo maligna score assessed by in vivo reflectance confocal microscopy after 1 month of imiquimod treatment for lentigo maligna management

BACKGROUND:Treatment of lentigo maligna (LM) is challenging because of the potential functional and esthetic surgical sequelae. Imiquimod has been proposed as a treatment for LM. Reflectance confocal microscopy (RCM) is a noninvasive method for the diagnosis of LM and margin assessment. OBJECTIVES:To compare the overall LM score (LMS) assessed by RCM before and 1 month after the start of imiquimod treatment compared to placebo and to define the immunohistochemical (IHC) profile of responders to imiquimod. METHODS:A controlled randomized study was conducted. Forty patients underwent RCM examination with calculation of the LMS at baseline and after 1 month of treatment. An IHC analysis of excised tissues was performed. RESULTS:The 1-month LMS was significantly lower in patients treated with imiquimod compared to those treated with placebo (P < .001). The criteria in the imiquimod-treated patients that demonstrated significant decrease were nonedged papillae; large, round pagetoid cells; atypical cells at the dermoepidermal junction; and follicular location of atypical cells. IHC analysis showed a higher level of interferon gamma in the resected specimens of patients responding to imiquimod (P = .04). LIMITATIONS:Sample size was small. CONCLUSION:Assessing the LMS by RCM was useful to monitor LM response to imiquimod accurately.