Effectiveness of indirect autofluorescent laryngoscopy in the diagnosis of cancerous and precancerous lesions of the larynx

ABSTRACT

Autofluorescent diagnostics are based on the ability of oxidized flavin mononucleotide [FMN] in normal cells to emit green fluorescence when exposed to blue light. Neoplastic cells have significantly lower concentrations of FMN and do not emit green fluorescence. Autofluorescent endoscopy is designed for early, accurate and minimally invasive diagnostics for laryngeal pathology. The aim of the present study was to evaluate the diagnostic potential and limitations of this imaging technique in comparison to laryngomicroscopy. In our investigation we used the System of Autofluorescent Endoscopy [SAFE 1000] designed by Pentax. We examined 32 patients using the SAFE 1000 system, and then all of the patients underwent indirect laryngomicroscopy [LMS]. In LMS, a biopsy was taken, and the diagnostic sensitivity of these two methods was compared according to the pathohistological diagnosis. For statistical evaluation we used Fisher's exact test. Comparable to indirect autofluorescence images, normal laryngeal mucosa showed a typical green fluorescence signal. Moderate and high epithelial dysplasia, carcinoma in situ and cancer displayed a diminished green fluorescence. False negative results were related to extreme hyperkeratosis. According to our results, the presented technique seems to be a promising diagnostic tool for the early detection of laryngeal cancer and its precursor lesions. It has the ability to give information about the nature of laryngeal lesions without devastation of the tissues. We believe that autofluorescent endoscopy in addition to laryngomicroscopy gives a more accurate diagnosis of laryngeal pathology than laryngomicroscopy alone