Intraoperative use of spectroscopic detection of protoporphyrin IX from oral 5‐aminolevulinic acid on basal cell carcinoma and squamous cell carcinoma during Mohs surgery

Abstract

Background and Objective Photodynamic diagnosis (PDD) using 5‐aminolevulinic acid (5‐ALA) has been used as an in vivo presurgical diagnostic tool for detecting occult tumor borders of ill‐defined basal cell carcinomas (BCCs), especially before Mohs micrographic surgery (MMS). However, most techniques reported in the literature involve gross examination or various digital detection systems to observe the amount of red light fluorescence after topical application of 5‐ALA. This study aimed to conduct a preliminary examination on the accuracy of intraoperative use of PDD by spectroscopic detection from oral 5‐ALA to identify tumor fluorescence from the peritumoral surgical pieces of tissue. Materials and Methods Qualitative evaluation of fluorescence spectroscopic detection was performed on 77 specimens from 13 patients with high‐risk BCC and 10 patients with high‐risk squamous cell carcinoma (SCC). All patients were orally administered with 5‐ALA preoperatively. The excised specimens were intraoperatively evaluated by scanning of the fluorescence spectrum. Results were compared with those of histopathology. Results Overall sensitivity and specificity were, respectively, 100% and 84.3% for spectroscopic detection. Although the negative predictive value was 100%, the positive predictive value was not sufficiently high for BCC (20%) nor for SCC (62.5%). Conclusion Fluorescence spectroscopic detection is as a step towards a possibly useful technique for decreasing the number of excisions in MMS. In its current state, however, it has no substantial clinical advantage. Lasers Surg. Med. 46:132–139, 2014. © 2013 Wiley Periodicals, Inc.