PAT4 Hepatoid adenocarcinoma of the colon: A case presentation. (Pathology).

PAT4 HEPATOID ADENOCARCINOMA OF THE COLON: A CASE PRESENTATION. Shawn B. Jackson, MD, Jorge M. Abdallah, MD, and Cristian I. Robiou, MD. East Carolina University, Brody School of Medicine, Pitt County Memorial Hospital, Greenville, NC.

Hepatoid adenocarcinoma (HAC) is an exceedingly rare tumor. It is often found in the gastrointestinal tract, particularly in the stomach. Adenocarcinoma with hepatoid differentiation has also been reported in the colon, bladder, gallbladder, lung, uterine cervix, pancreas, and ovary. We describe the case of a 55-year-old man with a history of atherosclerotic cardiovascular disease with atrial fibrillation/flutter who presented with progressive lower extremity numbness, diplopia, and ataxia for three-to-five weeks before admission. A paraneoplastic syndrome was considered as a possible cause, and an abdominal CT scan showed a mass in the ascending colon and lymphadenopathy. Multiple other lesions in the liver, lungs, and bone marrow were also found. An MRI of the brain later showed an 8 mm midbrain lesion consistent with an ischemic event. A right hemicolectomy specimen had an ulcerofungating, circumferential tumor in the ascending colon, measuring 5.5 cm in greatest dimension. Microscopically, the tumor has i nfiltrating borders, forming solid nests, trabeculae and cords. The tumor cells showed hepatoid features including moderate amounts of finely granular eosinophilic cytoplasm and round nuclei with prominent nucleoli. No adjacent adenomatous changes were found. The neoplasm invaded to the serosal surface. Nineteen of nineteen lymph nodes were involved with metastatic tumor and there were additional mesenteric deposits. Special stains revealed intracytoplasmic mucin in many tumor cells as well as diffuse positivity with monoclonal and polyclonal CEA; the latter with a focal cannalicularlike pattern. Strong granular cytoplasmic reactivity for [alpha]-1 antitrypsin was also present; however, an alpha feto-protein stain was negative. Due to this histologic appearance and pattern of staining, this tumor was best diagnosed as HAC.

A biopsy taken from one of several small liver nodules at the same time showed carcinoma with a similar histologic appearance. The patient has responded well to treatment with ironotecan (Captosar, CPT-11) with reduction of liver, lung, and bone metastases and disappearance of his paraneoplastic syndrome. In a case of HAG metastatic to the liver, a diagnosis of primary hepatocellular carcinoma must be considered. The diagnosis of colonic HAC depends on the presence of a mixture of morphological and immunohistochemical features of hepatocellular carcinoma and adenocarcinoma. HAC characteristically carries a very poor prognosis and tends to metastasize to the liver with extensive venous invasion.