Diagnostic accuracy of two-photon fluorescence microscopy in Mohs surgery of basal cell carcinomas

Mohs surgery has excellent outcomes but is time-consuming due to the use of intraoperative frozen sections. Two-photon fluorescence microscopy (TPFM) is a slide-free technique that generates H&E-like histology images in fresh tissue specimens in real-time which could accelerate treatment.

To determine the accuracy of TPFM with H&E coloring for the evaluation of basal cell carcinoma on Mohs specimens.

Frozen section analysis and TPFM images were acquired from 133 specimens following completion of Mohs surgery for basal cell carcinoma. Two Mohs surgeons who had not previously seen TPFM histology evaluated the TPFM images. Their evaluations (TPFM read) were compared to a consensus frozen section analysis (frozen section analysis read) graded by a dermatopathologist and separate Mohs surgeon.

The average sensitivity and specificity were 93.8% and 82.2%, respectively. If specimens that were discordant due to section plane differences or tissue fragments from frozen sectioning are excluded, average sensitivity and specificity improve to 95.0% and 94.3%, respectively, which is a truer measure of the diagnostic accuracy.

This study evaluated agreement between histology after conclusion of surgery.

Mohs surgeons can interpret H&E colored TPFM images with comparable accuracy to frozen sections on Mohs margins taken for basal cell carcinoma with minimal training.