A Cyto-histopathological Analysis of Oral Mucosal Lesions: with Special Reference to Clinical and Flow Cytometrical Findings

Abstract

In order to evaluate the diagnostic accuracy of exfoliative cytology (EC) in oral mucosal lesions (OML), we studied it and compared with histopathology, clinical findings and flow cytometrical analysis (FCMA). Two hundred and seventy five smear cases were obtained from 40 normal tissue samples (control) and OML ; leukoplakia (187), exophytic epithelial tumor or verrucous carcinoma (EET or VC) (8) and oral squamous cell carcinoma (OSCC) (40). As for FCMA, the DNA and proliferative indices (D.I. and P.I.) of all cases including the misdiagnoses were calculated. In leukoplakia without dysplasia, the accuracy rate of EC diagnosis was 70.0%, while leukoplakia with dysplasia was 26.7% for mild, 47.6% for moderate, and 84.2% for severe cases, respectively. All EET were misdiagnosed by EC, while OSCC had a 100% accuracy rate. The sparsity of atypical cells, which mostly contributed to the discrepancy in EC diagnosis of the under-diagnostic cases. Erythema, ulcers, Candida, nodular outgrowths and increased number of atypical cells that contributed to the over-diagnostic cases. The mean D.I. of leukoplakia without dysplasia was 1.8,while mild, moderate and severe dysplasias were 2.2, 3.5 and 3.9, and EET or VC and OSCC were 4.3 and 4.5, respectively. The P.I. values also showed the same tendency. Overall, 96 cases were cytologically misdiagnosed where 64 cases were under-diagnosed and 32 cases were over-diagnosed. Exact evaluation was made by flow cytometry (FCM) in 77 of 96 misdiagnostic cases (80.2%) of EC. Accurate diagnosis of OML especially oral epithelial dysplasia by clinical and cytological findings is still difficult to achieve. Mild and moderate dysplasias had lower accuracy rate compared to severe and OSCC cases. Main problems for under-diagnosis of dysplasia include limited number of atypical cells and for over-diagnosis include clinical and cytological findings. The FCMA of leukoplakia without dysplasia and mild dysplasia were significantly close, while EET or VC cases were closer to OSCC results. FCM gave significant results for all EET or VC cases. The authors conclude that FCM, though not a replacement for standard cytological examination or biopsy, would help to lessen the subjective evaluation of OML and in establishing strategies and follow-up protocols for patients with dysplasias and EET or VC. Our studies suggest that combination of EC and FCM is very useful in the evaluation of misdiagnostic cases.