Tumoral and Parenchymal Morphological Assessment in Liver Metastases of Colorectal Carcinoma: Micrometastasis, Peritumoral Lymphocytes, Tumor Budding and Differentiation are Potential Prognostic Factors

Introduction: Various potential prognostic histopathologic factors for colorectal carcinoma liver metastasis have been proposed. However, there is still no consensus on pathological reporting of colorectal carcinoma liver metastasis resection materials. The aim of this study was to investigate the relation between selected tumoral and parenchymal histopathologic features and prognostic factors for better characterization and prognostic prediction of the patients with colorectal carcinoma liver metastasis. Methods: Hematoxylin-eosin stained slides from 100 patients who underwent hepatic resection were evaluated. Pathologic characteristics; including number of tumor nodules, largest tumor size, status of surgical margin, tumor distance to closest margin, tumor necrosis, the presence of tumor capsule, tumor differentiation, perineural and lymphovascular invasion, micrometastasis, tumor budding, peritumoral lymphocytic infiltrate and parenchymal features including steatosis, steatohepatitis, lobular inflammation, confluent necrosis, hepatocyte ballooning, portal inflammation were assessed. For 49 patients who were treated with preoperative chemotherapy, tumor regression grade and chemotherapy-related parenchymal changes such as sinusoidal damage, venous obstruction, nodular regenerative hyperplasia, steatosis and steatohepatitis were also evaluated. Results: The presence of lymphovascular invasion (p < 0.001), micrometastasis (p=0.004), absent or mild peritumoral lymphocytic infiltration (p =0.013), high tumor budding score (p=0.033) and moderate/poor differentiation (p=0.022) were significantly associated with shorter overall survival. Lymphovascular invasion (p < 0.001) was an independent predictor of mortality in multivariate analysis. Conclusions: We conclude that tumor differentiation, lymphovascular invasion, micrometastasis, peritumoral lymphocytic reaction and tumor budding score are potential prognostic histopathological features and candidates for inclusion in pathology reports of colorectal carcinoma liver metastasis resections.