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

INTRODUCTION: Herein 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. CONCLUSION: Owing 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.

Structural transition of various-sized sphere-platelet mixtures.

Monte Carlo simulations on the structural change of hard sphere-platelet mixtures were performed to investigate the effect of particle size. We quantitatively analyzed local equilibrium structures of sphere-platelet mixtures with varying size ratios under various sphere and platelet density conditions. Based on the simulation results, we investigated the structural transitions such as isotropic to anisotropic, clustering, and so on. When a small amount of small-sized sphere is added to a large-sized platelet system, the mixture structure transitions from isotropic to nematic ones as the platelet number density increases. On the other hand, the platelet forms clusters with the addition of a large number of spheres. In a small platelet-large sphere system, the spheres form aggregates by increasing platelet density instead. The platelet and spherical particles exhibit different structural transitions depending on the size and density. In the limit of small and large size ratios, the structures of the platelet-sphere mixture obtained from the Monte Carlo simulation are close to those shown by previous theoretical and experimental studies, respectively. Because the primary actor shifts from sphere to platelet as the size ratio changes, the transition boundary shifts continuously. When the size ratio is close to unity, the most complicated behavior is observed, with both the platelet and sphere simultaneously acting the leading part.