Lentigo Maligna Treated With Microscopically Controlled Surgery: A 194‐Patient Retrospective Study

ABSTRACT Background Further studies are required to support the clinical value of paraffin‐embedded microscopically controlled surgery (MCS) in lentigo maligna (LM) and lentigo maligna melanoma (LMM). Methods This is a retrospective observational study to review histologically confirmed LM and LMM cases treated definitively and exclusively with paraffin‐embedded MCS, specifically, staged excision, with at least ≥ 6 months follow‐up if recurrence was absent. Results One hundred and ninety‐four patients were eligible for inclusion, with a median age of 72.5 years. Most cases were primary tumors (82%). Tumors were predominantly located on the face (167, 86.1%), especially on the cheek (73, 37.6%). Most of the cases were LM (141, 72.7%). LMMs had a median Breslow thickness of 0.48 mm and were mainly T1a (38, 71.7%) (8th edition of the AJCC staging system). Dermoscopy was routinely utilized to delineate the tumor border prior to surgery, and in 29 cases (15.0%), Wood's lamp was also employed. All patients achieved negative margins with paraffin‐embedded MCS. After a global median follow‐up of 34 months, seven patients (3.6%) had LR. LRR was higher in LMM (4/53, 7.5%) than LM (3/141, 2.1%) ( p = 0.09). The restricted mean survival time (RMST) at 36 months was 36.0 months for LM and 34.9 months for LMM. LMM patients tended to have LR earlier—on average, 1.1 months sooner in the first 36 months than LM patients ( p = 0.13). Given the low number of events ( n = 7), multivariable survival modeling was not used to prevent unstable or overfitted estimates. Conclusions Paraffin‐embedded MCS provides accurate margin control and low LRR for LM and LMM. image