Avaliação dos critérios diagnósticos da ceratose actínica através da microscopia confocal a laser

Abstract

The diagnosis of actinic keratosis (AK) is based primarily on clinical examination and eventually confirmed by histopathological analysis (HA), indicated in doubtful cases or refractory to treatment. The challenge is to establish the correct diagnosis through a minimally invasive evaluation, despite limited clinical-pathological agreement, especially regarding the degree of epidermal involvement and diagnosis of early squamous cell carcinoma (SCC). The objective of this study is to validate the analysis of AK by reflectance confocal microscopy (RCM), a non-invasive imaging method, with cellular resolution, that allows longitudinal follow-up of lesions, which enables a more detailed assessment of treatment response and a comparison between different therapeutic options. For this validation, the aim is to determine the relevant parameters for RCM evaluation, compared to HA, by calculating the sensitivity (S), specificity (E), positive (PPV) and negative (NPV) predictive values of each criterion found in AK. Through clinical examination, 25 AKs were selected for dermoscopy, RCM and shaving excision for HA. Statistical analysis was performed by hypothesis tests (McNemar for binary variables and Wilcoxon for continuous variable). There was no significant difference between RCM and HA for 5 of the 6 parameters analyzed. Statistically relevant criteria were: parakeratosis (p-value 0.4449690; S 90%; PPV 78.26%), hyperkeratosis (p-value 0.28821313; S 87.5%; E 100%; PPV 100%; NPV 25%), dyskeratosis (p-value 0.617075; S 85.71%; E 75%; PPV 94.74%; NPV 50%), atypia of spinous layer keratinocytes classified as mild, moderate or severe (p- 0.145032), and inflammation in epidermis (p-value 1.000000; S 75%; E 20%; PPV 78.95%; NPV 16.67%). RCM could not adequately measure inflammation in dermis (p-value 0.013328), despite good sensitivity (68%) and PPV (100%). RCM proved to be an effective method for AK diagnosis, with cellular resolution comparable to HA, with the advantage of a noninvasive approach, free of histological artifacts. The validation of keratinocyte atypia classification in 3 degrees, associated with the presence or absence of other 4 criteria, constitutes a potentially useful tool for further studies that address evolutionary comparisons of the same AK lesion over time, in a numerical and objective manner.