Contribuição de características morfológicas e imuno-histoquímicas para o diagnóstico de lesões serrilhadas colorretais.

Abstract

INTRODUCTION: In the past 30 years, there has been an increase in knowledge of serrated lesions of colorectum and their relationship with recently described molecular pathways. Despite the recent update of morphological criteria and nomenclature changes, the diagnosis of serrated lesions remains a challenge, what justifies the investigation of additional tools that can contribute to the diagnostic. OBJECTIVES: To apply the 2019 WHO classification to a sample of colorectal serrated lesions based on diagnostic, morphological and immunohistochemical characteristics; correlate morphological characteristics and patterns of expression of ANXA10, MUC1, BRAF, MLH1 and Ki-67, with the diagnoses of colorectal serrated lesions in the sample; to propose the use of a score to be applied to the diagnostic of sessile serrated lesions; and to compare conventional adenomas with serrated lesions in relation to diagnostic, clinical-epidemiological, morphological and immunohistochemical characteristics. MATERIAL AND METHODS: 172 colorectal polyps (serrated and conventional) were analyzed, and morphological characteristics were verified according to the new WHO classification and immunohistochemical expression of BRAF, ANXA10, MLH1, MUC1 and Ki-67. RESULTS: It were identified 108 serrated polyps and 64 conventional adenomas (CA). Most of the serrated polyps occurred in patients between 50 and 70 years (p = 0.016) and 50% of the sessile serrated lesions (SSL) was identified in the right colon (p<0.0001). Regarding morphological alterations, the presence of base crypt dilation, crypt irregularity and distal luminal serration were the most frequent characteristics in SSL. Cytoplasmic eosinophilia, pencilated nuclei and ectopic crypts were the main characteristics of traditional serrated adenomas. BRAF expression was observed in about 57.1% of hyperplastic polyps (HP) and 79.2% of SSL, 54.8% of HP and 89.6% of SSL showed positivity for ANXA10 and no expression was observed in CA (p<0.0001). Localization in the right colon, BRAF and ANXA10 expression showed increased chances of the diagnostic of a SSL (OR: 9.6; OR: 5.0 and OR: 24.2 - p=0.0005, 0.006 and 0.0002), which allowed the elaboration of a score with values from 0 to 9 and sensitivity and specificity of 66.67% and 83.33%, when considered 4 as a cutoff point. CONCLUSION: Distal luminal serration and irregularity of 03 or more crypts were the most frequent characteristics in SSL. The majority of PH showed serration in the proximal third, without crypt irregularity. BRAF expression was more frequent in HP and SSL and most SSL exhibited ANXA10 expression above 50%. The use of BRAF and ANXA10, together with the location of the lesion, may be an additional tool for the diagnosis of serrated lesions.