Locally Recurrent Lentigo Maligna and Lentigo Maligna Melanoma: Characteristics and Time to Recurrence After Surgery

BACKGROUND Various studies have reported local recurrence (LR) rates after surgical treatment of lentigo maligna (LM) and lentigo maligna melanoma (LMM). However, the time to LR of LM/LMM is not currently known, as few studies report time to LR and have long-term follow-up. OBJECTIVE To define time to LR in LM/LMM after surgical treatment, and to describe features of observed LR. MATERIALS AND METHODS Retrospective single-center study of consecutive patients presenting with locally recurrent LM/LMM. RESULTS Six hundred forty-nine cases of LM/LMMwere reviewed; 29 (21 LM, and 8 LMM) of 41 locally recurrent cases had original histology reports and were included. The mean time to LR was 57.5 months (range 7-194). For cases presenting as primary LM, LR was also in situ in 14/21 (67%) of cases. Seven of 21 LM recurred as LMM. Of the 8 primary LMM, 3/8 (37.5%) presented with subsequent LMM and all were slightly deeper on re-excision. CONCLUSION The mean time to LR of LM/LMM is at least 57.5 months, underscoring the importance of long-term follow-up. Seven of 21 LM recurred as invasive disease, but the lack of development of LMM from LM in most recurrent cases confirms LM is slowly progressive.