Mixed pancreatic hepatoid carcinoma: A surgical case report and literature review.

Background: Hepatoid carcinoma (HC) is a rare type of malignant tumor that shared similar features of morphology and immunohistochemistry with hepatocellular carcinoma (HCC). Pancreatic HC exists as either pure or mixed type. Mixed pancreatic HC is extremely rare, with only a few cases reported in the literature to date. Because of the rarity of mixed pancreatic HC, its clinical features including incidence, characteristics, and prognosis remain unclear. We herein report a case of a 49-year-old man who was diagnosed with mixed pancreatic HC with neuroendocrine differentiation and was treated with pancreaticoduodenectomy and adjuvant chemotherapy. We also review the existing case reports in literature.

Presentation: A 49-year-old man was admitted to our hospital after a chronic abdominal pain in the upper right quadrant. Abdominal ultrasound revealed only one low-density retroperitoneal mass measured at 20 × 48mm in size in the pancreatic-duodenal junction, whereas contrast-enhanced computed tomography (CT) revealed three lymphatic neoplasms measured at 28 × 22 × 30 mm, 27 × 33 × 38 mm and 22 × 35 × 48 mm in size in the retroperitoneal pancreatic-duodenal junction. Ultrasound-guided tumor biopsy was performed. Pathological reading of tumor biopsy suspected of Paraganglioma/pheochromocytoma. Laparotomic retroperitoneal tumoral resection and lymphadenectomy was then performed. Histological reading was lymphatic metastasis of primary pancreatic hepatocellular carcinoma with neuroendocrine differentiation, which were immunohistochemically positive for CKAE1/AE3, Hepatocyte paraffin 1, Chromogranin. After three weeks of the first surgery, the patient was assigned with Positron Emission Tomography - Computed Tomography (PET-CT) before adjuvant chemotherapy, revealing a low-density high-metabolism mass, 26 × 28 mm in size within the parenchyma of pancreatic head. Laparotomic pancreaticoduodenectomy and standard lymphadenectomy was performed to resect one mass, which revealed the same immunohistology features with the first mass. The patient was followed up with FOLFIRINOX protocol, and after 12 cycles, there was no evidence of postoperative recurrence.

Discussion: There are few reported cases describing pancreatic hepatoid carcinoma, especially mixed form with other histological associated component. Neuroendocrine differentiation is the majority associated component with 62.5% of all cases of mixed - type form.

Conclusion: Primary pancreatic hepatocellular carcinoma with neuroendocrine differentiation was rare, biopsy and immunohistochemistry appeared with high diagnostic value in this case. The prognosis of pancreatic HC depends on the extent and tumor eradication, and in this case we recorded no postoperative complications and no recurrence in the 6-month follow-up period.