Utility of Acridine Orange Fluorescence Microscopy in Cytodiagnosis of Oral Lesions

Abstract

Introduction: Oral exfoliative cytology is a reasonably effective technique for rapid initial evaluation of suspicious lesions. Exfoliated cells obtained from saliva, lavage or scrapings are ideally stained with Papanicolaou stain. Acridine orange stain imparts nuclear and cytoplasmic fluorescence in malignant cells which have increased nuclear activity. This cytochemical property can be utilized for diagnosis of cancer. Aim: The aim was to determine utility of Acridine Orange (AO) fluorescence microscopy as a rapid and easier method for oral cytodiagnosis as compared to Papanicolaou stain. Materials and Methods: The study group included a total of 50 cases, 25 cases clinically suspicious of malignancy (Group I) and 25 non suspicious cases, e.g., inflammatory lesions etc., (Group II) in both sexes, aged > 40 years. The control group comprised 5 individuals in the age group of 20 years and above, without any clinically observable lesions. Scrapings were obtained from oral mucosa, stained with AO and Pap stains, visualised with fluorescence and light microscopy, respectively, and results were compared & analysed statistically. Results: AO staining: Amongst 25 cases in group I, 18 were confirmed as Squamous Cell Carcinomas (SCC) on histopathology. Sixteen out of 18 confirmed cases (88.89%) showed greenish yellow nuclear fluorescence with brownish red cytoplasmic fluorescence. In group II, 18 cases showed too little fluorescence to be labelled as positive with limited nuclear details which were hence counted as negative for fluorescence. Papanicolaou staining: In group I, 13 out of the 18 confirmed cases (72.22%) were positive for malignancy. In group II, only one case was false positive for malignancy and the rest were negative. The differences between the two groups were compared using Chi-square test. A p value of less than 0.05 was considered statistically significant. Conclusion: AO stain reliably demonstrated malignant cells based on differential fluorescence – a cytochemical criterion. Thus, AO proved to be more sensitive than Papanicolaou staining for diagnosing malignancies. Hence, it can be used for screening and early detection of potentially malignant lesions.

Keywords

• exfoliative cytology
• fluorescent stain
• oral cancer