CHICAGO – The future looks bright for to rule out malignancy, Ann M. John, MD, asserted at the annual meeting of the American College of Mohs Surgery.
Dr. Ann M. John
“With the advent of dermoscopy, dermatologists were able to elucidate both benign and malignant patterns to help further guide their decision to biopsy or not. This increased diagnostic accuracy of suspicious lesions by 30%, while reducing the benign to malignant ratio of biopsies performed from 18:1 to 4:1. However, there are still lesions that are equivocal on dermoscopy, as we all know, and for this, there’s reflectance confocal microscopy,” observed Dr. John, of Robert Wood Johnson Medical School, New Brunswick, N.J.
RCM is a device technology that’s been cleared by the Food and Drug Administration since 2008 for the imaging of clinically suspicious lesions. It employs laser scanning to assess the light-scattering properties of cells in the epidermis and dermis, generating images with resolution comparable to histology.
RCM took a back seat initially while American dermatologists were gradually coming to embrace dermoscopy, which their European colleagues had done years earlier. Now, with the availability of handheld RCM for use in the dermatology clinic, expect RCM to assume a growing role in daily practice.
To illustrate the power of RCM as a diagnostic aid, she presented a single-center retrospective study of 1,189 clinically suspicious skin lesions that were equivocal on dermoscopy and then assessed using RCM with 1 year of subsequent patient follow-up. Overall, 155 lesions were deemed positive for cancer or atypia by RCM, while 1,034 were determined to be benign. Of those 155, 46 lesions were considered false positives because of their benign appearance on histologic inspection of the biopsy sample. Only 2 of the 1,034 lesions identified as negative by RCM proved to be false negatives on the basis of clinical changes within 1 year.
The overall sensitivity and specificity of RCM was 98.2% and 99.8%, respectively, with a positive predictive value of 70.3% and a negative predictive value of 99.8%.
The entire RCM procedure takes a skilled technician 15-20 minutes per lesion. As a practical matter, other investigators have estimated that RCM results in a cost savings of about $308,000 per million health plan members per year by reducing the need for biopsies (Dermatol Clin. 2016 Oct;34[4]:367-75).
In addition to evaluating clinically suspicious lesions, other situations in which RCM offers practical value include its use directly before the first cut during Mohs surgery in order to determine the margins of atypia; ex vivo imaging of Mohs margins, which has been shown to be comparable with frozen sections in accuracy but takes only one-third of the time; and imaging of biopsied lesions in order to determine the diagnosis relatively quickly, Dr. John noted.
She reported having no financial conflicts regarding her study.