What is New in the 2019 World Health Organization (WHO) Classification of Tumors of the Digestive System: Review of Selected Updates on Neuroendocrine Neoplasms, Appendiceal Tumors, and Molecular Testing

Abstract

Context.— The 5th edition of the World Health Organization classification of digestive system tumors discusses several advancements and developments in understanding the etiology, pathogenesis, and diagnosis of several digestive tract tumors. Objective.— To provide a summary of the updates with a focus on neuroendocrine neoplasms, appendiceal tumors, and the molecular advances in tumors of the digestive system. Data Sources.— English literature and personal experiences. Conclusions.— Some of the particularly important updates in the 5th edition are the alterations made in the classification of neuroendocrine neoplasms, understanding of pathogenesis of appendiceal tumors and their precursor lesions, and the expanded role of molecular pathology in establishing an accurate diagnosis or predicting prognosis and response to treatment.

Serum lipid levels correlate to the progression of gastric cancer with neuroendocrine immunophenotypes: A multicenter retrospective study

“…As a heterogeneous cohort, although all GCNEI tumors express NE markers, their composition is complex. In the 2019 WHO classification, NE differentiation (NED) is defined by the presence of both morphological and immunohistochemical phenotype of NE, and it would not change the designation of an adenocarcinoma, only if the NE differentiation reached 30% [1] . However, a growing amount of evidence supported that a <30% NEC component or a component only with NE immunophenotypes in GC could contribute to more malignant biological behaviors and worse prognosis [14 , 23] .…”

“…Cases were selected according to the following criteria: i. neoadjuvant chemotherapy had not been applied; ii. pathological diagnoses were NEC, NEC with adenocarcinoma components, adenocarcinoma with NEC components, MANEC, or GC with NE differentiation, which were confirmed by immunohistochemical (IHC) staining for synaptophysin (Syn) and chromogranin A (CgA) [1] ; iii. Preoperative lipid profile test was performed and the data were available ( Fig.…”

Clinicopathological characteristics and prognosis of 232 patients with poorly differentiated gastric neuroendocrine neoplasms

“…In addition, MANEC has also been replaced by mixed neuroendocrine and nonneuroendocrine tumors (MiNENs), which contain a wider range of contents. Most of the NEN components in MiNEN are NEC and may also be NETs; in addition to adenocarcinoma, other components, such as squamous cell carcinoma, may also occur in non-NEN components, but each component must account for more than 30% and be classified when reporting[ 7 ]. The 8 th edition gastric cancer tumor-node-metastasis staging system was used for staging[ 8 ].…”

Primary hepatic neuroendocrine tumor

“…PHNETs have no specific imaging features and are typically misdiagnosed as other hepatic lesions such as hepatocellular carcinoma (HCC) or cholangiocarcinoma (CCC) (2). The pathological results of PHNETs do not differ from those of other NETs (6). However, neither imaging studies nor pathology studies are able to differentiate a primary PHNET lesion from a secondary metastatic NET; therefore, the diagnosis of PHNET is particularly concerning (7).…”