Abstract: Gastrointestinal invasive micropapillary carcinoma (GIMPC) is a rare subtype of adenocarcinoma in the gastrointestinal tract. Compared with conventional adenocarcinomas, GIMPC is more progressive, and its outcome is rather unfavorable. Immunohistostaining of Mucin 1/epithelial membrane antigen is evident on the stromal-facing surface of clusters of neoplastic cells. A broad differential diagnosis, including the papillary adenocarcinoma, the conventional adenocarcinoma with multiple lymphovascular invasion, metastic micropapillary carcinoma, and tumor buds, should be considered. GIMPC is distinct from conventional adenocarcinoma in terms of morphology, immunophenotype, and biological behavior. It is highly aggressive and exhibits poor prognosis.