Advanced Imaging System Investigated for Faster Diagnosis of Skin Cancers

Biopsies of nonmelanoma skin cancers (NMSC) were analyzed in a new study using 2-photon fluorescence microscopy (TPFM), and this technology proved highly effective and accurate at diagnosing cancers that included basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).

The study findings were published online recently in JAMA Dermatology.

This ability to provide point-of-care diagnoses has potential to improve on the current standard of care, conventional histology, which is paraffin section histologic analysis that can take days or weeks. In addition, there is potential for TPFM to better treatment with Mohs microscopic surgery, according to an accompanying editorial.

In the study, 29 freshly excised biopsy specimens were immediately imaged using TPFM at Rochester Dermatologic Surgery between October 2019 and August 2021.

“The imaged biopsies were subsequently submitted for paraffin histology to produce coregistered images,” the investigators wrote. Among these, 12 pairs made up the training set, 15 pairs made up a masked evaluation, and 2 were excluded because they could not be coregistered.

The investigators’ primary objective was “to demonstrate that TPFM imaging of NMSC can occur within minutes of obtaining biopsies and provide similar histological features to those of conventional histology and evaluate TPFM diagnostic performance with respect to conventional histology,” with the goal of someday providing same-day diagnosis and treatment.

For BCC, following a dermatopathologist’s review of the evaluation set, there was a 93.3% accordance rate, indicating an identical diagnosis was made with TPFM compared with the usual paraffin histology of hematoxylin and eosin. This analysis also had ratings of 100% for sensitivity (95% CI, 48%-100%), specificity (95% CI, 69%-100%), and accuracy (95% CI, 78%-100%).

With SCC, the results for sensitivity and accuracy were slightly lower, but still positive, while specificity was again 100% (95% CI, 54%-100%). Sensitivity was 89% (95% CI, 52%-100%) following TPFM and accuracy was 93% (95% CI, 68%-100%).

Overall, for its utility in diagnosing NMSC across all samples, TPFM demonstrated sensitivity, specificity, and accuracy results of 93% (95% CI, 66%-100%), 100% (95% CI, 3%-100%), and 93% (95% CI, 68%-100%), respectively.

All of the patients whose samples were used had presented for Mohs microscopic surgery.

“The results of this comparative effectiveness pilot study suggest that TPFM captures histological characteristics of NMSC that are present in conventional histology,” the study researchers concluded, “which reveals its potential as a rapid, point-of-care diagnostic alternative that does not need extensive sample preparation or retraining for image evaluation.”

They note that their findings indicate great potential for NMSC diagnosis, but additional investigation is needed to validate their findings. These studies should include review by more than 1 dermatopathologist, expand the number of biopsies analyzed, incorporate benign dermatologic conditions “that are representative of typical clinic populations,” and assess using TPFM in nonbiopsy workflows.

Reference

Ching-Roa VD, Huang CZ, Ibrahim SF, Smoller BR, Giacomelli MG. Real-time analysis of skin biopsy specimens with 2-photon fluorescence microscopy. JAMA Dermatol. Published online September 7, 2022. doi:10.1001/jamadermatol.2022.3628