Well differentiated grade 3 pancreatic neuroendocrine tumors compared with related neoplasms: A morphologic study.

Background: Pancreatic neuroendocrine neoplasms with a Ki-67 labeling index greater than 20% were reclassified in 2017 by the World Health Organization into well differentiated (WD) and poorly differentiated grade 3 neuroendocrine carcinoma (NEC). The authors describe the cytologic features of grade 3 WD pancreatic neuroendocrine neoplasms compared with grade 2 neoplasms and NEC.

Methods: Fine-needle aspirates from 65 pancreatic neuroendocrine neoplasms were reviewed, and their cytomorphologic features were compared across grade 2, WD grade 3, and PD small cell type (PD-S), large cell type (PD-L), and type not otherwise specified (PD-NOS) neoplasms.

Assessment of cytologic differentiation in high-grade pancreatic neuroendocrine neoplasms: A multi-institutional study.

Background: Well-differentiated (WD) and poorly differentiated (PD) pancreatic neuroendocrine neoplasms are biologically distinct entities with different therapies and prognoses. WD neoplasms with elevated proliferation (Ki-67 > 20%) have been shown to have an overlapping histology with PD neuroendocrine carcinomas. This study compared expert cytomorphologic assessments of differentiation in pancreatic neuroendocrine neoplasms in a multi-institutional study.

Biliary carcinomas: pathology and the role of DNA mismatch repair deficiency.

The pathology of biliary carcinomas is diverse with different gross and histological features in tumors arising in the different segments of the biliary system. Various epidemiological risk factors, varied genetic makeup, and tissue microenvironment are contributory factors. As biliary tumors have been shown to be a part of the Lynch syndrome tumor spectrum, it is plausible to speculate that DNA mismatch repair (MMR) deficiency plays a role in biliary tumors.