Reflectance confocal microscopy (RCM)-based criteria for progression of lower-lip squamous cell carcinoma: A prospective study

Background: Actinic cheilitis (AC) presents as a diffuse clinical-histopathological alteration throughout the lower lip. Objectives: To analyze AC lesions using reflectance confocal microscopy (RCM) and evaluate criteria for the early diagnosis of incipient squamous cell carcinoma (SCC). Methods: This prospective study comprised cases of clinically diagnosed AC. RCM was performed over the entire extension of the lower lip. The sites that showed the highest degree of morphological alteration by RCM, according to established criteria for AC and SCC, were biopsied. The RCM findings and histopathology were correlated to establish the precise and early diagnosis of SCC. Results: A total of 61 cases that had been clinically diagnosed with AC were included. The RCM findings that correlated independently with SCC were: nonedged papillae (sensitivity 84% and specificity 88%, p < 0.0001, and OR 42), cell-filled papillae (sensitivity 82% and specificity 93%, p < 0.0001, and OR 71.3), inflammation (sensitivity 68% and specificity 68%, p = 0.0163, and OR 4.8), large and roundish cells in the lamina propria (sensitivity 65% and specificity 100%, p < 0.0001, and OR infinity), and nests in the lamina propria (sensitivity 54% and specificity 100%, p < 0.0001, and OR infinity). An independent histopathological analysis classified the cases as partial epithelial dysplasia (25 cases, 41%) and SCC (36, 59%), and in 57 cases (94%), the results agreed with the categorization that was rendered by the RCM exam. Conclusions: RCM can be used to monitor AC cases, guide the biopsy site, and identify the early progression of AC to SCC with good sensitivity and specificity.