WEDNESDAY, March 5, 2025 -- Handheld reflectance confocal microscopy (HH-RCM) is promising for detecting subclinical lentigo maligna (melanoma; LM/LMM), according to a study published in the March issue of the Journal of the European Academy of Dermatology & Venereology.

Yannick S. Elshot, from the Netherlands Cancer Institute in Amsterdam, and colleagues examined the effects of presurgical mapping using HH-RCM in 117 consecutive LM/LMM cases from 2015 to 2023. The diagnostic accuracy of HH-RCM in detecting subclinical LM was examined. Margin and follow-up outcomes were compared to those of a historical cohort of 94 patients (2003 to 2014).

The researchers found that in 60 percent of cases, subclinical LM was detected by HH-RCM. The mapping procedure resulted in modified management in 33 patients (27 percent), most consisting of limited surgery with adjuvant imiquimod or imiquimod monotherapy (15 and 14 patients, respectively). The remaining 84 cases underwent HH-RCM-assisted surgery. In 96.5 percent of patients, histological margins were cleared, with a median histological margin of 3.0 mm, which was significantly higher than in the historical cohort (81 percent; margin of 2.0 mm). For detecting the extent of subclinical LM, the sensitivity was 94 percent and the specificity was 84 percent. For detection of LMM, the negative predictive value was 94 percent; 75 percent of the initially missed LMM were identified during the HH-RCM mapping procedure. The local recurrence rate was 1.6 percent compared with 25 percent in the historical cohort.

"Our findings support the efficacy of HH-RCM for precisely identifying surgical margins, reducing recurrence rates, and detecting subclinical LMM," the authors write. "This allows for an informed selection of patients suitable for nonsurgical treatment."