Fluorescence investigations to classify malignant laryngeal lesions in vivo

Background. The extent of surgical resection for malignant laryngeal lesions influences voice quality. An instrument to estimate histopathologic grading of dysplasia in vivo may spare normal tissue without increasing the risk of local failure. Methods. Laryngeal lesions (N = 39; 21 after administration of delta-aminolevulinic acid (ALA)) were investigated with laser-induced fluorescence, and the results correlated to histopathologic grading in 4 groups: non/mild dysplasia (I), moderate dysplasia (II), severe dysplasia/cancer in situ (III), and carcinoma. Results. At 337-nm excitation, there were differences in the fluorescence ratio I(431)/I(390) between groups I/III and carcinoma. Following 405-nm excitation, /(500 nm) group I differed significantly from group III and cancer. The sensitivity for the fluorescence method was 89%, and the specificity was 100%. Conclusions. There are differences in the in vivo tissue fluorescence between tissue with different gradings of dysplasia and carcinoma.