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

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.