This issue of Pathology Case Review is devoted to recent advances and update in the pathology of the pancreas. The articles provide insights into the current nomenclature, classification, diagnosis, differential, and clinical and prognostic aspects of various pancreatic neoplasms and lesions that are gaining recognition by pathologists, clinicians, and surgeons in their daily practice.
The intraductal papillary-mucinous neoplasms (IPMNs) of the pancreas have only recently been recognized as a clinical and pathological entity and it has become clearer that they constitute a heterogeneous group with several histopathological subtypes that have different biological properties with different prognostic implications. The article by Furukawa et al reviews the different phenotypic types of this intriguing group. They also highlight the prognosis on IPMN with different degree of dysplasia and that with minimal invasion. Intraductal papillary-mucinous neoplasm may not show overt mucin production. Such cases may sometimes make a proper diagnosis challenging. Farris et al present a case of intraductal papillary neoplasm with paucity of mucin as an example and provide a detailed review on the morphology, differential diagnosis, and immunohistochemical and molecular characteristics of this neoplasm. Among the various phenotypes of IPMN, the oncocytic type represents a rare variant. Professor Benoît Terris elegantly reviews this rare entity with respect to its clinical aspect and pathological features and its differential diagnosis.
Intraductal tubular carcinoma of the pancreas is an intraductal neoplasm that may sometimes be challenging to distinguish from the intraductal tubular variant of acinar cell carcinoma, pancreatobiliary-type intraductal papillary mucinous carcinoma, and intraductal tubular adenoma. Tajiri et al provide insight on characterizing this entity by illustrating an example of such case.
Mixed acinar-(neuro)endocrine carcinoma is a malignant epithelial neoplasm of the pancreas demonstrating both acinar and (neuro)endocrine differentiation. It is gaining increasing recognition, partly because of the increasing usage of immunohistochemistry. The article of Ohike et al addresses the histologic, immunohistochemical, and electron microscopic features of mixed acinar-(neuro)endocrine carcinoma. This review highlights its differential diagnosis with other mimicking neoplasms in the pancreas.
Tanaka et al illustrate the morphological characteristics and immunohistochemical features of a case of undifferentiated carcinoma of the pancreas, followed by a thorough discussion highlighting the undifferentiated carcinoma with osteoclast-like giant cells. Molecular and ultrastructural findings are also described.
Solid serous adenoma is a rare variant of the serous cystic neoplasms of the pancreas. Lam-Himlin and Hruban discuss the clinical, radiologic, and pathologic features, as well as the differential diagnosis of this rare neoplasm, especially its distinction from other neoplasms with clear cytoplasm.
Finally, Notohara et al write an extensive review on autoimmune pancreatitis, a unique inflammatory condition of the pancreas that may mimic cancer clinically. Both lymphoplasmacytic sclerosing pancreatitis and idiopathic duct-centric chronic pancreatitis are discussed, and various extrapancreatic IgG4-related diseases are addressed. This review also highlights an important role for pathologists in diagnosing autoimmune pancreatitis.
We are extremely grateful to all the contributors for sharing their expertise and knowledge in forming this issue. We hope that the information provided highlights and elucidates the topics of pancreas pathology.