Colorectal adenocarcinoma with enteroblastic differentiation: a clinicopathological study of five cases

Aims Colorectal adenocarcinoma with enteroblastic differentiation (CAED) is a rare malignancy, and its clinicopathological characteristics have not yet been fully elucidated. This study aimed to elucidate the clinicopathological features of CAED through immunostaining of enteroblastic lineage markers alpha-fetoprotein (AFP), glypican-3 (GPC3), and spalt-like transcription factor 4 (SALL4). Methods and results We identified five CAED cases (0.3%) from 1666 colorectal carcinomas, analysed the clinicopathological characteristics and performed immunostaining for AFP, GPC3 and SALL4. Three patients were male and two were female. All cases were located in the sigmoid colon or rectum. Histologically, all cases showed adenocarcinoma composed of cuboidal or columnar cells, with clear cytoplasm resembling the primitive gut; one case exhibited a partial hepatoid pattern. The depth of invasion was T2 and T3 in two and three cases, respectively. Lymphatic/venous invasion was found in all cases (100%), lymph node metastases in four of five cases (80%) and distant metastases in three of five cases (60%) (liver, two cases; lung, one case). Two patients died as a result of their disease during follow-up. Immunohistochemically, SALL4 and GPC3 were each positive in four of five cases, whereas one case with a hepatoid component was positive for AFP. All three CAED cases with distant metastases were GPC3-positive. Conclusions CAED was frequently located in the sigmoid colon or rectum, showed aggressive behaviour, such as lymph node metastasis and distant metastasis, and had a dismal prognosis. In addition, CAED was immunoreactive to AFP, GPC3 or SALL4, indicating that these markers may be characteristic of CAED.