Hepatoid adenocarcinoma arising from heterotopic pancreas of the ileum: A case report

Abstract

Introduction: Hepatoid adenocarcinoma (HAC) is a rare neoplasm with a striking morphologic similarity to hepatocellular carcinoma. The most common sites of HAC are the stomach, lung, and pancreas.

Case report: Here we report a rare case of HAC arising from the heterotopic pancreas (Heinrich type II) in the ileum with lymph node metastasis. A 56-year-old man was admitted to our hospital presenting with bloody stools under no obvious predisposing causes. The colonoscopy and the gastroscopy showed no pathological findings. A computed tomography scan showed an intussusception of ileum. Then partial resection of ileum was performed with end-to-end anastomosis and appendectomy. Histopathological examination showed a malignant transformation of heterotopic pancreas (Heinrich type II) in the ileum. We made the diagnosis of HAC based on clinical pathological features and immunochemical staining. The patient received chemotherapy and died 9 months later.

Conclusion: To our best knowledge, this is the first reported case of HAC originated from a heterotopic pancreas in the ileum. The clinical pathological features and immunochemical staining are important for correct diagnosis of HAC.

Figure 1

Abdominal CT scan of HAC arising from heterotopic pancreas in the ileum. A, CT scan showed an equal density nodule sized about 2.5 cm × 1.8 cm located on the proximal ileum (indicated by red arrow). B, We found no obvious enhancement in the contrast (indicated by red arrow). C, The edge of the ileum was smooth and clear, and we found no malignant sign, but 1 enlarged lymph node (about 1.7 cm × 1.1 cm) on the mensentery (indicated by red arrow). CT = computed tomography, HAC = hepatoid adenocarcinoma.

Figure 2

Histological and immunohistochemical analysis of HAC arising from the heterotopic pancreas in the ileum. A, The solid nests and trabecular structure mimicked the pattern of hepatocellular carcinoma of polygonal atypical cells, with eosinophilic cytoplasm and round-to-oval nuclei. B and C, At 1 edge of the tumor, pancreatic tissues were clearly defined with ducts and acini, and islet cells were absent, diagnosed as Heinrich type II heterotopic pancreas. There was merging of heterotopic pancreas with HAC. D, HepPar1-diffuse cytoplasmic staining of the tumor cells. E, CK7-diffuse cytoplasmic and membranous staining of the tumor cells. F, Villin-focal cytoplasmic staining of the tumor cells. A, D–F = magnification ×200, B = magnification ×40, C = magnification ×100. CK7 = cytokeratin 7, HAC = hepatoid adenocarcinoma, HepPar1 = hepatocyte paraffin 1.