Multicentric ENETS morphological and molecular appraisal of high-grade gastroenteropancreatic neuroendocrine neoplasms (HG-GEP-NEN): Distinguishing NET G3 from NEC

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Introduction: HG-GEP-NEN are classified into neuroendocrine tumours grade 3 (NET G3) and neuroendocrine carcinomas (NEC). This distinction is crucial as it affects patient prognosis and treatments but can be challenging.

Aim(s): This study evaluates the role of histomolecular tools in distinguishing NET G3 from NEC, focusing on the confidence of pathologists when dealing with such difficult cases.

Materials and methods: 8 senior and 5 junior pathologists from 7 ENETS CoE independently reviewed digital slides from 192 challenging HG-GEP-NEN cases in 3 successive steps: 1) morphology + neuroendocrine markers, 2) Ki-67 index, 3) p53/Rb1 expression. At each step, diagnosis and confidence level were recorded. Consensual cases (CC) were defined as >80% of pathologists having the same diagnosis. All ambiguous cases (ambNEN) at step 3 were reviewed in an on-site consensus meeting (step 4).

Conference:

Presenting Author: Tihy M

Authors: Tihy M, Solstad O, Oudijk L, Bräutigam K, Bani M,

Keywords: HG-GEP-NEN, neuroendocrine neoplasm, NEC, NET G3, Classification, Review, criteria, diagnosis, pathology,