Colorectal Micropapillary Adenocarcinoma: Molecular Mechanisms and Clinical Implications.

Colorectal micropapillary adenocarcinoma (CMPA) is a rare and highly aggressive subtype of colorectal cancer with high metastatic potential and the proportion of CMPA to the entire tumor ranged from 5 to 80% but was usually less than 30% of the entire lesion. Its distinctive histological features and molecular mechanisms have rendered it a subject of current research. CMPA is characterized by the arrangement of micropapillary structures, which is frequently associated with high invasiveness of lymphatic and blood vessels, thereby significantly increasing the risk of metastasis to lymph nodes and distant organs. At the molecular level, mutations in genes such as KRAS, BRAF, and TP53 enhance tumor invasiveness by modulating signaling pathways and promoting epithelial-mesenchymal transition. Furthermore, the tumor microenvironment(TME) of CMPA exhibits a higher mesenchymal component and a lower content of tumor-infiltrating lymphocytes (TILs), which is strongly associated with poor patient prognosis. During the diagnostic process, immunohistochemical markers such as CK20, CDX2, and TP53 play a crucial role in the identification and classification of CMPA. At present, surgical resection remains the primary treatment for CMPA. However, its high recurrence rate and propensity to metastasize indicate the necessity for further research into more effective targeted and immunotherapeutic options. Future studies should focus on the molecular mechanisms, immune microenvironmental properties, and individualized treatment strategies for CMPA, with the objective of improving clinical outcomes for patients.