Relação entre o tempo de fixação e a presença de artefatos de retração que simulam invasões linfovasculares em neoplasias malignas humanas

Abstract

Malignant neoplasms are one of the main causes of death worldwide and represent a major challenge for global public health. As important as understanding the mechanisms involved in the development and progression of neoplasms is assertive diagnosis, which is essential for effective treatment of the disease. Lymphovascular invasion (LVI) is an important prognostic marker in the staging of malignant neoplasms, playing a critical role in assessing the cancer’s aggressiveness and metastatic potential. The presence of neoplastic cells inside lymphatic and/or blood vessels is considered a high-risk indicator for metastatic dissemination, directly influencing therapeutic decisions. The histological technique of obtaining paraffin sections with subsequent hematoxylin-eosin (HE) staining is the most widely used in routine pathology for the histopathological analysis of malignant neoplasms. Fixation is a critical step in the proper preparation of these samples to ensure the preservation of tissue morphology and consequent diagnostic accuracy, a condition that also depends on the technical ability and experience of the pathologist, as well as variations in the morphological particularities of the neoplastic tissue. Therefore, this study investigates the impact of chemical fixation times with formaldehyde for 6, 48 and 72 hours in malignant neoplasms of the breast (n=3), colon (n=3) and uterus (n=3) in order to identify whether there is interference in the interpretation of differentiating empty spaces between the stroma and parenchyma as being retraction artifacts (RA) or lymphovascular invasions, during the histopathological evaluation of three pathologists. The invasion pattern of the lesions was also analyzed and correlated with the fixation time and the appearance of these artifacts. The results showed that retraction artifacts are common in histological slides made using the paraffin technique for histopathological analysis of malignant neoplastic samples, with a high percentage of doubts in the differentiation between RA and ILV, reinforcing the need for further studies. Formaldehyde fixation times of 6 and 72 hours showed better results in terms of morphological integrity and the presence of artifacts mimicking lymphovascular invasion, with 6 hours being the most appropriate time for colonic and uterine tissues with an expansive invasion pattern. In breast lesions, the 6-hour time was not enough to adequately preserve the tissue, highlighting the influence of the infiltrative invasion pattern in this type of sample. The study recommends expanding the discussion on pre-analytical and analytical factors, invasion patterns, histological types and the molecular and cellular bases of malignant neoplasms, with a view to reducing errors and improving the reproducibility of results.