Sensitivity and specificity for detecting basal cell carcinomas in Mohs excisions with confocal fluorescence mosaicing microscopy

Recent studies have demonstrated the ability of confocal

fluorescence mosaicing microscopy to rapidly detect basal cell carcinomas

BCCs directly in thick and fresh Mohs surgical excisions.

Mosaics of confocal images display large areas of tissue with high

resolution and magnification equivalent to 2, which is the standard

magnification when examining pathology. Comparison of mosaics to

Mohs frozen histopathology was shown to be excellent for all types of

BCCs. However, comparisons in the previous studies were visual and

qualitative. In this work, we report the results of a semiquantitative

preclinical study in which 45 confocal mosaics are blindly evaluated

for the presence or absence of BCC tumor. The evaluations are made

by two clinicians: a senior Mohs surgeon with prior expertise in interpreting

confocal images, and a novice Mohs fellow with limited experience.

The blinded evaluation is compared to the gold standard of

frozen histopathology. BCCs are detected with an overall sensitivity of

96.6%, specificity of 89.2%, positive predictive value of 93.0%, and

negative predictive value of 94.7%. The results demonstrate the potential

clinical utility of confocal mosaicing microscopy toward rapid

surgical pathology at the bedside to expedite and guide surgery.