Clinical features associated with the invasive component in lentigo maligna of the head and neck: A retrospective study of 175 cases.

BACKGROUND: Lentigo maligna (LM) can develop into lentigo maligna melanoma (LMM) with risk of metastatic dissemination. LMM may be underestimated on the basis of the initial biopsy. The invasion may affect both the therapeutic options and the prognosis. OBJECTIVES: To identify the clinical features associated with invasive forms of LM and factors associated with its recurrence. METHODS: A retrospective, single-centre study of consecutive LM and LMM histologically confirmed and treated by surgery between 2009 and 2014. RESULTS: In total, 175 patients with LM/LMM were surgically treated in our establishment. In men, lesions were more likely to be in the "peripheral zone" (41.8%), while in women they were seen more often in the "central zone" (P=0.001). In multivariate analysis, only the peripheral zone was found to be associated with a risk of invasion (P=0.008). The rate of recurrence was 9% and lesions were more likely to be primary LMM (P=0.0006) excised with clear margins. CONCLUSION: The treatment of choice in LM with non-clear margins must be re-excision, especially for lesions situated in the peripheral zone. Close follow-up is recommended due to risk of recurrence, even in the case of clear margins.