Clinicopathological Features Of Colorectal Invasive Micropapillary Carcinoma And Its Relationship With Lymph Node Metastasis

Objective1. To investigate the clinicopathological features and immunohistochemical phenotypes of colorectal adenocarcinoma with invasive micropapillary carcinoma (IMPC) component.2. To investigate the relationship between colorectal adenocarcinoma with invasive micropapillary carcinoma (IMPC) component, lymphovascular invasion, and lymph node metastasis.Methods1. HE staining and immunohistochemistry staining were used to observe the clinicopathological features and immunohistochemical phenotypes in11cases of colorectal adenocarcinoma with invasive micropapillary carcinoma (IMPC) component.2.131cases of colorectal adenocarcinoma with invasive micropapillary carcinoma component were evaluated by HE staining and immunohistochemical staining. The main pathological features, percentage of IMPC component, lymphovascular invasion, and lymph node metastasis were assessed, and compared to296cases of conventional colorectal adenocarcinoma.Results1. In the11cases of IMPC,6were males and5were females. The age ranged from26to83years (median61, average59.3).9tumours located in rectum and2located in the junction of descending and sigmoid colon. The maximum diameter of the tumours ranged from1.5cm to6.5cm.6tumours showed ulcerating shape and5tumours showed ulcerated fungating shape. Microscopically, all the carcinomas were mainly composed of atypical cells arranged in micropapillary structures.5of them are purely invasive micropapillary carcinoma.There were lymphatic invasion and venous invasion in all cases. Regional lymph nodes revealed metastases in all cases. During the operation, metastases to the liver in3cases, peritoneal dissemination in1case, and metastases to the left inguinal lymph nodes in1case were detected.6months after operation2patients died.8months after operation IMPC metastased to the uterus in1case and4months later the patient died.36months after operation IMPC metastased to the liver in1case.6-38months after operation4patients survival with free tumours.4patients were lost in follow-up after operation. 2. The maximum diameter of the tumors of the IMPC group was significantly lower than the conventional group. The degree of differentiation, the lymph node metastatic rate, the average number of metastatic lymph nodes, and the number of cases with lymphovascular tumor emboli were all significantly higher in the IMPC group (P=0.000).The rate of distant metastasis at operation was higher in the IMPC group (14.50%) compared to the conventional group (10.81%) even though statistical significance was not observed (P=0.278). In IMPC group, as the IMPC component increased, the rate of lymph node metastasis also showed an increasing trend. in the proportion of components in the entire tumor, the rate of render the apparent increasing trend. The rate of lymph node metastasis were53.04%、67.74%and85.51%in conventional group, adenocarcinoma with≤10%IMPC component and adenocarcinoma with>10%IMPC component respectively; The difference was statistically significant(P=0.000).Conclusion1. Colorectal adenocarcinoma with invasive micropapillary carcinoma (IMPC) component is a highly malignant carcinoma. The IMPC component must be considered in the differential diagnosis with tumor thrombi in the lymphatic and venous, metastatic carcinoma.2. Compared to conventional colorectal adenocarcinomas, the colorectal carcinomas with IMPC component show a significantly higher rate of lymphovascular invasion, lymph node metastasis and distant metastasis. The percentage of IMPC component in colorectal adenocarcinoma is significantly correlated to the rate of lymph node metastasis. Therefore, the presence of IMPC component and degree of tumor differentiation are predictor factors of lymph node metastasis.