Fluorescence staining of laryngeal neoplasms after topical application of 5-aminolevulinic acid: Preliminary results

Background and Objective: The prognosis of patients suffering from laryngea l carcinomas can be improved by early diagnosis. Exact demarcation of tumor margins could contribute to an optimum preservation of the larynx. Therefo re, the aim of the present study was the evaluation of 5-aminolevulinic aci d (5-ALA)-induced protoporphyrin IX (PPIX) fluorescence as a new diagnostic procedure for the detection of laryngeal cancer. Study Design/Materials and Methods: Sixteen patients with suspected maligna ncies of the larynx received 0.6 wt% 5-ALA-NaCl solution by means of a medi cal nebulizer. After a period of 1-2 hours, the patients underwent microlar yngoscopy under white light and fluorescence illumination (lambda(ex) = 375 -440 nm). A quantitative analysis of the fluorescence contrast between neop lastic and surrounding tissue was performed using an optical multichannel a nalyzer. Results: Carcinoma, carcinoma in situ, and dysplasia showed red fluorescenc e that could be attributed to the 5-ALA-induced formation of PPIX. The surr ounding normal tissue exhibited autofluorescence in the green spectral rang e, which was greatly reduced within the tumor. The results of macroscopic r ed fluorescence staining were correlated with the histologic diagnosis. Conclusion: According to these preliminary results, the presented method se ems to be a promising adjunct diagnostic procedure for the early identifica tion of malignant neoplasms ill the larynx. The aim of further investigatio ns is the assessment of sensitivity and specificity and an evaluation of fl uorescence-guided laser resections of laryngeal cancer. Lasers Med. Surg. 2 5:414-420, 1999. (C) 1999 Wiley-Liss, inc.