Hepatoid Adenocarcinoma of the Rectum With Liver Metastasis in Patient With Ulcerative Colitis

Abstract

Hepatoid adenocarcinoma (HA) is a rare malignant tumor of extrahepatic origin that morphologically and immunophenotypically resembles hepatocellular carcinoma. We report a case of a 38-year-old Caucasian male with 13 year history of ulcerative colitis who initially presented to an outside facility with three months of diarrhea, mild abdominal pain, and ten-pound weight loss. Outpatient colonoscopy revealed severely ulcerated rectosigmoid mucosa with necrotic features and he was transferred to our facility for further workup of presumed ischemic colitis. CT abdomen showed a large, 8.1 x 9.4 x 6.6 cm hepatic mass with portal vein thrombus and rectosigmoid thickening. Liver protocol MRI did not demonstrate characteristic contrast washout seen in hepatocellular carcinoma (HCC). Alpha-feto protein (AFP; 15,523 ng/mL) and carcinoembryonic antigen (CEA; 20.3 ng/mL) were elevated. The patient subsequently underwent triple phase CT which was also not consistent with HCC. Scrotal ultrasound to rule out a primary testicular malignancy was negative; however, human chorionic gonadotropin (beta hCG) was elevated, increasing the concern for extragonadal yolk sac tumor. The patient underwent liver biopsy and repeat colonoscopy with rectal biopsies. Histologic morphology and immunophenotype from both specimens were consistent with hepatoid adenocarcinoma. Given these findings a diagnosis of hepatoid adenocarcinoma of the rectum with hepatic metastasis was made. The patient was subsequently started on palliative FOLFOX chemotherapy. Hepatoid adenocarcinoma is a rare malignant tumor of extrahepatic origin whose features mimic those of hepatocellular carcinoma. Most cases have been reported as arising in the stomach, though HA has also been described in the small and large intestines, lung, ovary, uterus, bladder, pancreas, and gallbladder. HA is often metastatic at time of diagnosis and carries a poor prognosis. Most cases of HA arising in the intestines have been described in patients with inflammatory bowel disease, who are known to be at increased risk of developing adenocarcinoma of the GI tract. Hepatoid adenocarcinoma should be considered in the differential diagnosis of malignant lesions in the IBD patient.Figure: A. A liver core biopsy low power image depicting diffuse infiltration of the tissue by carcinoma. B &C. High power images reveal a mixed hepatocellular/trabecular and glandular architecture composed of cytologically atypical eosinophilic cells vaguely resembling atypical hepatocytes. Immunohistochemistry (not shown) exhibits positive staining for pankeratin, cdx-2, polyclonal CEA, monoclonal CEA, alpha-fetoprotein, glypican-3, SALL-4, and focal positivity for CK20, and is negative for CK7, HepPar-1, Vimentin, CD31, and CD34.