Reflectance confocal microscopy slashes needless excisions

Adding reflectance confocal microscopy (RCM) to dermatoscopy significantly reduces excision of benign lesions without missing aggressive melanomas, according to a prospective real-world study published in JAMA Dermatology.

“The main finding is that the systematic use of confocal microscopy on suspicious lesions can reduce the excision of benign lesions almost 50%—without significant loss of melanoma and zero loss of thick melanoma,” said lead author Giovanni Pellacani, MD. He is a professor of dermatology at Sapienza University of Rome in Italy.

Investigators randomized a total of 3165 patients seen at 3 dermatology referral centers between January 2017 and December 2019 to standard care (clinical and dermatoscopic evaluation) with or without adjunctive RCM (VivaScope 1500; VivaScope GmbH).

Among 2392 excised lesions, investigators identified 572 melanomas (23.9%), with an overall number needed to excise (NNE) of 4.2.¹ Adjunctive RCM detected 278 melanomas, versus 294 for usual care. However, RCM showed almost twice the positive predictive value (33.3) of usual care (18.9), and a benign-to-malignant ratio of 1.8:1, versus 3.7:1 for usual care. Additionally, RCM reduced NNE by 43.2% (3.0 versus 5.3 for standard care), exceeding a predetermined cost-effectiveness threshold of a 30% reduction in unnecessary excisions that was determined by a previous study.²

Among 1583 patients assigned to RCM, investigators sent 45.5% for immediate excision. Among 853 lesions referred for digital dermatoscopic follow-up (DDF), 15 (1.8%) proved to be melanoma. However, more than half of these tumors were melanoma in situ, and no melanomas found at DDF were thicker than 0.5 mm.

“We were expecting good results,” said Pellacani. “We were very happy to achieve the absence of thick melanomas in the monitoring group, and to have only 1.8% of lesions referred to follow-up being diagnosed as melanoma later on.” In clinical practice, he added, around 4% of lesions referred for DDM typically are diagnosed as melanoma.

“Instead of referring to excision any kind of lesion you consider to be suspicious for melanoma,” Pellacani said, “you may get a noninvasive real-time biopsy with confocal microscopy, saving surgery, scars, and morbidity to the patient.”

RCM can help dermatologists decide which lesions really require excision, he said. “It is evident that with confocal microscopy, you have much higher accuracy, incrementing both sensitivity and specificity.”

European guidelines recommend dermatoscopy for diagnosing all pigmented and non-pigmented lesions (Level A) and suggest that RCM can be used for further evaluation of clinically or dermatoscopically equivocal lesions (Level C).³ “This study increases the evidence of its utility in melanoma diagnosis.” Every dermatologist in Italy uses a dermatoscope, he said, and RCM is readily available throughout Europe, with most major skin-cancer centers offering the technology.

As a next step, investigators are compiling precise, real-life data on the cost-effectiveness of RCM. “It is effective and safe,” he said. “The next question is, how much can you save using this technology? Is this economically convenient?” At press time, Pellacani and colleagues had completed comparative research with multiple RCM systems. These findings may reach publication later this year.

Simultaneously, the investigators are exploring how a handheld RCM probe (VivaScope 3000, VivaScope GmbH) could increase sensitivity of melanoma diagnosis, especially in challenging situations such as patients with dysplastic mole syndrome or facial macules.

The standalone RCM system used for the present study maps lesions through a mosaic process. The handheld probe allows quicker examinations, Pellacani said, but it cannot construct mosaics of large fields of view. “It is a bit less precise, but we believe it is a good tool for screening, to identify equivocal lesions.” Presently, investigators are reviewing their data for possible publication in 2023.

Disclosures:

Pellacani reports no relevant conflicts of interest.

References:

1. Pellacani G, Farnetani F, Ciardo S, et al. Effect of reflectance confocal microscopy for suspect lesions on diagnostic accuracy in melanoma: a randomized clinical trial [published online ahead of print, 2022 Jun 1]. JAMA Dermatol. 2022;10.1001/jamadermatol.2022.1570. doi:10.1001/jamadermatol.2022.1570

2. Pellacani G, Pepe P, Casari A, Longo C. Reflectance confocal microscopy as a second-level examination in skin oncology improves diagnostic accuracy and saves unnecessary excisions: a longitudinal prospective study. Br J Dermatol. 2014;171(5):1044-1051. doi:10.1111/bjd.13148

3. Garbe C, Amaral T, Peris K, et al. European consensus-based interdisciplinary guideline for melanoma. Part 1: Diagnostics - Update 2019. Eur J Cancer. 2020;126:141-158. doi:10.1016/j.ejca.2019.11.014