Pre-surgical mapping of recurrent lentigo maligna of the face with handled confocal microscopy: a useful tool to downstage surgical repair

Lentigo maligna (LM) poses significant management challenges when recurrent, owing to post-surgical scarring and subclinical tumor extension that limit reliable clinical margin assessment. In this prospective, single-center study, we evaluated the impact of handheld reflectance confocal microscopy (HH-RCM) on pre-surgical margin delineation and surgical outcomes in patients with recurrent facial LM. Adults previously treated with complete surgical excision of facial LM who developed a histologically confirmed recurrence at the same anatomical site within 24 months were enrolled. Recurrent LM was defined as a new lesion arising after a disease-free interval and confirmed by biopsy or excision. Patients were managed either with HH-RCM-guided margin mapping (n = 21) or with standard clinical and dermoscopic assessment alone (n = 33). In the HH-RCM group, tumor margins were systematically mapped using a standardized adhesive tape technique to delineate the outermost confocal extension of LM prior to surgery. Surgical margins were verified by permanent-section histopathology in all cases. The primary outcome was the rate of invasive reconstruction, while secondary outcomes included post-clearance defect size and local recurrence at 12 months. Complete margin clearance in a single surgical stage was achieved more frequently in the HH-RCM group (85.7%) compared with the clinical group (60.6%). HH-RCM mapping resulted in significantly smaller surgical defects (mean diameter 1.7 +/- 0.6 cm vs. 2.4 +/- 0.8 cm; p < 0.01) and a reduced need for invasive reconstructive procedures (28.6% vs. 60.6%; p = 0.009). Local recurrence rates at 12 months were low and comparable between groups (4.7% vs. 6.1%). HH-RCM-guided margin mapping improves surgical planning in recurrent facial LM by enabling precise delineation of subclinical tumor extension, allowing more conservative resections and reducing reconstructive burden without compromising short-term oncologic control.