Fluorescence imaging for the demarcation of basal cell carcinoma tumor borders

Basal cell carcinoma (BCC) is a common malignancy accounting for 80% of all nonmelanoma skin cancers. Mohs micrographic surgery (MMS) is considered superior to alternative treatments, but the procedure is time consuming and costly. Alternative simpler techniques to facilitate accurate tumor demarcation are therefore in demand. Fluorescence imaging following application of 5-aminolevulinic acid is a noninvasive diagnostic technique that gives rapid information about the superficial extent of the skin tumor.

To ascertain whether fluorescence imaging improves the clinical tumor border assessment by investigating the consistency between tumor size determination by MMS, clinical assessment, and fluorescence imaging.

Eighteen patients with histologically verified nodular BCCs on the face scheduled for MMS were included in the study. The night before the surgical procedure, 5-aminolevulinic methyl ester cream was applied to the lesion. The following morning, tumor borders were determined clinically (clinical size), after illumination with Wood's light (fluorescence size), and by the tumor defect left on the skin surface following removal of the MMS specimen (Mohs size).

The median tumor sizes were 93.05 mm2 (Mohs size), 61.05 mm2 (clinical size), and 72.75 mm2 (fluorescence size). The interclass correlation coefficients between Mohs size and fluorescence size was 0.984 and Mohs size and clinical size was 0.752.

Tumor border estimation by fluorescence imaging and clinical assessment underestimate the genuine tumor size determined by MMS; however, the fluorescence size showed a higher degree of consistency with the Mohs size than did the clinical size.