S2962 Hepatoid Adenocarcinoma - A Rare Malignancy

Abstract

INTRODUCTION: Hepatoid adenocarcinoma (HAC) is a rare subtype of gastric cancer. It histologically resembles hepatocytes and can produce alpha fetoprotein (AFP). We present a case of HAC with metastasis to the liver, thus mimicking a hepatocellular carcinoma (HCC). Clinical history and immunohistochemical stains are the key to diagnosis. CASE DESCRIPTION/METHODS: We report a 67-year-old male with a history of hypertension who presented to the hospital with epigastric abdominal pain, nausea, and vomiting that was progressively worsening for the past 4 months. Physical exam was remarkable for mild epigastric tenderness with palpation. Laboratory tests showed a hemoglobin of 9.5 gm/dL with iron studies consistent with iron deficiency anemia. The AFP, CA 19-9, and CEA were normal. CT showed extensive mural thickening of the stomach with extensive mediastinal and retroperitoneal lymphadenopathy as well as a hypo-enhancing mass in the left lobe of the liver measuring 3.3 × 3.2 × 2.7 cm. There were no exam, lab, or imaging findings suggestive of chronic liver disease. We performed an upper endoscopy which revealed a large fungating, infiltrative and ulcerated circumferential mass involving the gastric body and fundus. Multiple biopsies were taken which showed fragments of gastric mucosa infiltrated by a poorly differentiated neoplasm. Immunohistochemical stains supported hepatoid differentiation of the neoplasm. Specifically, CK19 and B72.3 stains favored HAC over HCC. Liver biopsy was subsequently performed and showed a similar histologic appearance. Thus, the patient was diagnosed with stage IV HAC with metastasis to the liver. He was followed up by oncology as an outpatient and started on FOLFOX chemotherapy. DISCUSSION: HAC of the stomach with metastasis to the liver can be difficult to diagnose as it can mimic HCC. Our case is even more unusual in that the AFP was normal, although this does not exclude either HAC or HCC. Unfortunately, HAC is an aggressive cancer that carries a poor prognosis. Like in our case, many are diagnosed at an advanced stage and there are no guidelines for the optimal chemotherapy regimen. Since our patient’s AFP levels were normal, he can only be monitored by interval imaging. Fortunately, our patient had excellent baseline functional status, which will hopefully improve his outcomes and tolerance to treatment. With HAC, clinical context and specialized immunohistochemical stains must be considered to make the correct diagnosis and prevent delay in treatment.Figure 1.: Endoscopic picture of Antrum with Mass.Figure 2.: Endoscopic picture of Endoscopy of the body of the stomach.Figure 3.: Endoscopic picture of the Fundus.