Hepatoid adenocarcinoma of the colon: a rare case report and review of the literature

Hepatoid adenocarcinoma is a rare subtype of adenocarcinoma, which usually occurs in the stomach. The occurrence of this adenocarcinoma in the colon is even less common. Herein, we presented an extremely rare case of hepatoid adenocarcinoma in the colon. The patient was a 54-year-old male, who had hematochezia for three months. Enteroscopy detected a mass in his transverse colon. No mass was detected in the patient's liver by ultrasound scan. Histologically, tumor cells were observed to form solid-cell nests or cords. The tumor cells were polygonal, with abundant eosinophilic or clear cytoplasm, which mimicked hepatocytes. The tumor cells had marked atypia, with an active mitotic index, and large nucleoli. Necrosis was common in the tumor tissues, and focal hemorrhage was observed. Immunostaining showed expression of CK and GPC-3 in the tumor cells. The tumor cells were negative for CK7, CK20, CDX-2, hepatocytes, synaptophysin, and carcinoembryonic antigen (CEA). The Ki-67 index was 80%. As such, the tumor was diagnosed as hepatoid adenocarcinoma according to the clinical, microscopic and immunostaining findings. The patient underwent surgery and chemotherapy and had no recurrence at the four-month follow-up. Hepatoid adenocarcinoma in the colon is extremely rare and needs to be differentiated from metastatic hepatocellular carcinoma to improve patient clinical outcomes.