A case of pancreatic ductal adenocarcinoma with enteroblastic, neuroendocrine, and squamous differentiation with p53 overexpression and loss of Rb expression.

introductionHerein we report a case of an extremely rare pancreatic adenocarcinoma with enteroblastic differentiation (AED), an underrecognized histological subtype. Moreover, the tumor was mixed with a neuroendocrine carcinoma (NEC), which is also a rare malignancy in the pancreas. CASE PRESENTATION: The patient was an elderly male who was incidentally diagnosed with a 35 mm-sized pancreatic head tumor and underwent pancreatoduodenectomy. Histopathologically, the tumor was composed of four different types: conventional ductal adenocarcinoma, AED, NEC, and squamous cell carcinoma. Interestingly, p53 overexpression and loss of Rb expression, which are characteristic findings of NEC, were observed in all components. He had been received adjuvant chemotherapy after the surgery, however, he died of bath-related cardiac arrest 14 months after surgery. DISCUSSION: In the stomach, AED, a carcinoma resembling fetal gut epithelium, is a rare but established subtype and is considered a related entity of hepatoid carcinoma (HAC). However, gastric AED and HAC differ to some extent. In contrast to the stomach, extragastric AED, including pancreatic AED, is extremely rare, and its biological features are unclear. A mixed tumor with NEC is a complex phenomenon, but it is occasionally reported in extragastric AED. The histogenesis of mixed AED-NEC can be resolved by determining p53 and Rb status.

conclusionOwing to their rare and novel nature, extragastric AED is under-recognized or confused with HAC. Further studies and the establishment of an extragastric AED classification are required.