Behavioral laterality is widely found among vertebrates, but has been little studied in aquatic invertebrates. We examined behavioral laterality in attacks on prey shrimp by the cuttlefish, Sepia lycidas, and correlated this to their morphological asymmetry. Behavioral tests in the laboratory revealed significant individual bias for turning either clockwise or counterclockwise toward prey, suggesting behavioral dimorphism in foraging behavior. Morphological bias was examined by measuring the curvature of the cuttlebone; in some the cuttlebone was convex to the right (righty), while in others, the cuttlebone was convex to the left (lefty). The frequency distributions of an index of cuttlebone asymmetry were bimodal, indicating that populations were composed of two types of individuals: "righty" and "lefty." Moreover, an individual's laterality in foraging behavior corresponded with the asymmetry of its cuttlebone, with righty individuals tending to turn counterclockwise and lefty ones in the opposite direction. These results indicate that cuttlefish exhibit behavioral dimorphism and morphological antisymmetry in natural populations. The presence of two types of lateral morph in cuttlefish provides new information on the relationship between antisymmetric morphologies and the evolution of individual laterality in behavioral responses in cephalopods. The implications of these findings for the interpretation of ecological meaning and maintenance mechanisms of laterality in cuttlefish are also discussed.

BACKGROUND Schwannoma of the pancreas is extremely rare. We report a case of pancreatic schwannoma that was difficult to distinguish from pancreatic carcinoma before surgery. CASE SUMMARY A 66-year-old male underwent a right-lobe hepatectomy for hepatocellular carcinoma. Post-surgical computed tomography showed a 10 mm long solid mass with ischemia, with no expansion into the main pancreatic duct. Upon magnetic resonance cholangiopancreatography, the tumor had high signal intensity in diffusion weighted images, consistent with pancreatic carcinoma. Endoscopic ultrasound (EUS) was performed to obtain more information about the tumor, and showed a 14 mm solid and hypoechoic mass in the pancreatic body. Contrast enhanced EUS revealed that the tumor showed a hyperechoic mass in the early phase, and the contrasting effect continuation was very short; findings also consistent with pancreatic carcinoma. Thus, we preoperatively diagnosed his condition as a pancreatic carcinoma and performed distal pancreatectomy with splenectomy. Microscopic examination showed that the tumor was in fact a benign schwannoma. Histology showed a proliferation of spindle-shaped cell in a vague fascicular and haphazard pattern, with palisading arrangement. CONCLUSION Schwannoma of the pancreas is very rare, however, clinicians should consider schwannoma as the differential diagnosis for pancreatic tumors.

BACKGROUND Chronic pancreatitis occasionally requires surgical treatment that can be performed with various techniques. Often, this type of surgery presents with postoperative complications. We report a case of a successful retrograde pancreatojejunostomy for chronic pancreatitis and infected pancreatic cysts. CASE SUMMARY A 62-year-old male with a 10-year history of chronic pancreatitis presented with epigastric pain for one week and a 20 kg weight loss over one year. Computed tomography showed stones in the pancreas (mainly the head), expansion of the main pancreatic duct, and thinning of the pancreatic parenchyma. Magnetic resonance imaging showed infected pancreatic cysts connected to the stomach with a fistula from the splenic hilum to the caudal portion of the liver’s lateral segment. An endoscopic retrograde pancreatography was performed; the guide wires could not pass through the stones in the pancreas and therefore, drainage of the main pancreatic duct was not achieved. Next, a distal pancreatomy and splenectomy were performed; however, the pancreatic juice in the remaining parenchyma was blocked by the stones. Hence, we performed a retrograde pancreatojejunostomy and Roux-en-Y anastomosis. The patient had no postoperative complications and was discharged from the hospital on postoperative day 14. CONCLUSION A distal pancreatomy, retrograde pancreatojejunostomy, and Roux-en-Y anastomosis could be an effective surgical procedure for intractable chronic pancreatitis.

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