Pancreatic pathology traditionally involves postoperative pathological diagnosis and comparison with imaging. Preoperative diagnosis has partly relied on pancreatic cytology. However, its clinical contribution has been limited due to issues, such as sample quality and volume. However, the advent of endoscopic ultrasound-guided fine-needle aspiration/biopsy (EUS-FNA/B) has significantly changed pancreatic pathology. Particularly, the ability to perform pathological diagnosis before treatment has become crucial in the pancreatic tumor domain, in which many tumors are unresectable, providing important diagnostic evidence. Recently, the efforts of gastroenterologists have stabilized sample quality and volume, contributing significantly to improvements in pathological diagnostic performance. Conversely, the sample volume obtained by EUS-FNA/B remains relatively small compared to obtained in the case of other diseases, and issues such as interfacility variability, still remain to be addressed. Therefore, to stabilize and improve diagnostic accuracy, we reported on the classification of pathological diagnoses of pancreatic solid tumors to improve the pathological diagnosis of pancreatic ductal adenocarcinoma. It demonstrated that clarifying the characteristic features and delegating the consensus on "suspicious for malignancy" to each facility resulted in improved inter-pathologist diagnostic agreement. This study provides an overview of the diagnostic classification and useful information for daily clinical practice.

Endoscopic ultrasound-guided fine needle aspiration/biopsy (EUS-FNA/FNB) is widely accepted as a safe and reliable method for the pathologic diagnosis of pancreatic lesions. Although the incidence of adverse events (AEs) associated with EUS-FNA/FNB is low, some AEs have been reported including perforation caused by the EUS scope, puncture-related bleeding, pancreatitis, pancreatic fluid leakage, and infection. Sedation-related AEs such as respiratory depression, circulatory depression, bradycardia, and arrhythmias have also been reported. In addition, there have been reports in recent years of needle tract seeding (NTS) in patients with pancreatic cancer undergoing preoperative transgastric puncture. Although the incidence of AEs is not high, it is essential to recognize and manage potential AEs to perform EUS-FNA/FNB safety.

More than 30 years have passed since endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) was first conducted. Since then, remarkable technological advances have been achieved, not only in endoscopes and puncture needles, but also in terms of techniques. Different puncture techniques, such as the door-knocking, fanning, torque, wet-pull, stylet slow-pull, and suction methods, have enhanced the diagnostic performance of EUS-FNA. Furthermore, aspiration techniques such as the suction, stylet slow-pull, and wet-suction methods have also been reported. Moreover, various on-site evaluations after tissue collection using EUS-FNA have enhanced pathological diagnosis. In the future, with the development of genomic medicine, it is anticipated that devices and techniques that facilitate safer and easier EUS-FNA will be created to address the demand for high-quality and sufficient tissue collection.

Comprehensive genomic profiling (CGP) in pancreatic cancer has advanced since its introduction in Japan in 2019. CGP has the potential to offer tailored therapies, yet challenges like inadequate tissue samples persist. Innovations in endoscopic techniques, device selection, and collaboration during EUS-FNA/B procedures are enhancing CGP's success rate. Recent strides in genomic and protein analysis using EUS-FNA/B specimens offer diagnostic promise, and ongoing progress in genome analysis holds the potential for treatment optimization and complements pathological diagnoses with minimal invasiveness. However, obtaining sufficient tissue for accurate assessment remains a frontline challenge. Despite the common use of EUS-FNA/B in tissue diagnosis, its limitations in detecting small lesions persist, emphasizing the need to balance precision and invasiveness in sampling. Embracing genomic medicine's role in therapy selection and aiding pathological diagnoses is crucial. Continued technical advancements, like liquid biopsy, offer hope for diagnosing challenging lesions. Integrating perspectives from gastroenterologists and pathologists is vital for navigating the complexities of CGP testing in pancreatic cancer and driving its clinical application.

The indications for preoperative diagnosis of pancreatic tumors by EUS-FNA/B have been extended in recent years. Preoperative or pre-treatment differentiation of common pancreatic cancer from comparatively rare low-grade tumors or unusual pancreatic cancer by EUS-FNA allows selection of an appropriate treatment strategy and surgical procedure. However, EUS-FNA/B for pancreatic tail cancer should be performed carefully due to the possibility of needle tract seeding. EUS-FNA for cystic tumors of the pancreas is rarely performed in Japan due to concerns about peritoneal seeding and cyst rupture. In contrast, in Europe and the United States, the intracystic fluid is commonly used for malignant diagnosis and differential diagnosis. For neuroendocrine tumors, preoperative grade prediction has been reported to have a diagnostic accuracy rate of around 85% in the last 10 years. EUS-FNA for solid pseudopapillary neoplasms is useful in differentiating them from neuroendocrine tumors and pancreatic acinar cell carcinoma. However, it must be performed with extreme caution due to reports of peritoneal dissemination and tumor rupture.

Background: Myxofibrosarcoma is one of the most common malignant soft tissue tumors of the extremities and trunk. We report a case of primary myxofibrosarcoma of the paraspinal erector spinae that metastasized to the pancreas 7 years later.

Case: An 87-year-old man was referred to our hospital because a tumor of the pancreatic body and tail was found on contrast-enhanced computed tomography (CT) scan for a close examination of abdominal pain. The patient had a myxofibrosarcoma of the primary paraspinal erector spinae muscle that had gone without reoccurrence since being resected 7 years earlier. Contrast-enhanced ultrasonography revealed a segmental mesenchymal tumor with abundant internal blood flow in the pancreatic body and tail. We performed a distal pancreatectomy and made a pathological diagnosis of pancreatic metastasis of primary myxofibrosarcoma of the paraspinal erector spinae, which had been resected 7 years earlier.

Discussion: Myxofibrosarcoma is characterized by its tendency to metastasize to various solid organs, and tends to recur long after the initial surgery. Metastatic pancreatic sarcomas themselves are rare, and the difficulty of accurate diagnosis and early treatment, as well as the limitations of treatment options, remain challenges.

Conclusion: We have experienced a case of one-year recurrence-free survival after surgical resection of pancreatic metastasis of myxofibrosarcoma.

Herein, we present a case of omental dissemination of pancreatic cancer found in an incarcerated inguinal hernia in a 66-year-old male patient. The patient was transferred to our hospital with vomiting and right groin swelling. An abdominal CT showed an incarcerated omentum in his right inguinal hernia, and pancreatic tail tumor with multiple liver metastasis and ascites. We attempted manual reduction which could not be achieved and an emergency operation was performed. In the hernia sac, a hard omental tumor was found and resected. 1,500ml of ascites was removed and a hernioplasty was performed by the iliopubic tract repair method without mesh. The histopathological diagnosis of the resected omentum revealed dissemination of pancreatic ductal adenocarcinoma. However, the patient died 11days later. Pancreatic cancer presented with incarcerated inguinal hernia has been reported to be very rare.

A woman in her 60s with jaundice and cholangitis was admitted to our hospital to undergo examination of a pancreatic tumor. A contrast-enhanced computed tomography (CT) scan for acute pancreatitis 5 months ago showed a 20mm mass with a cystic component. However, on a CT scan preformed at admission, the tumor with its cystic component had enlarged to 40mm with enhanced part. We performed endoscopic retrograde cholangiopancreatography (ERCP) for bile duct drainage and the tumor was diagnosed as an acinar cell carcinoma (ACC) by transpapillary biopsy. Radical surgical resection was performed after neo-adjuvant chemotherapy (modified FOLFIRINOX). This case study highlights one important characteristic of ACC, which is that it may develop morphological changes within a short period of time.