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. 2018 Dec;31(12):1770-1786.
doi: 10.1038/s41379-018-0110-y. Epub 2018 Aug 23.

A common classification framework for neuroendocrine neoplasms: an International Agency for Research on Cancer (IARC) and World Health Organization (WHO) expert consensus proposal

Guido Rindi  1 , David S Klimstra  2 , Behnoush Abedi-Ardekani  3 , Sylvia L Asa  4 , Frederik T Bosman  5 , Elisabeth Brambilla  6 , Klaus J Busam  2 , Ronald R de Krijger  7 , Manfred Dietel  8 , Adel K El-Naggar  9 , Lynnette Fernandez-Cuesta  3 , Günter Klöppel  10 , W Glenn McCluggage  11 , Holger Moch  12 , Hiroko Ohgaki  3 , Emad A Rakha  13 , Nicholas S Reed  14 , Brian A Rous  15 , Hironobu Sasano  16 , Aldo Scarpa  17 , Jean-Yves Scoazec  18 , William D Travis  2 , Giovanni Tallini  19 , Jacqueline Trouillas  20 , J Han van Krieken  21 , Ian A Cree  22
Affiliations

A common classification framework for neuroendocrine neoplasms: an International Agency for Research on Cancer (IARC) and World Health Organization (WHO) expert consensus proposal

Guido Rindi et al. Mod Pathol. 2018 Dec.

Abstract

The classification of neuroendocrine neoplasms (NENs) differs between organ systems and currently causes considerable confusion. A uniform classification framework for NENs at any anatomical location may reduce inconsistencies and contradictions among the various systems currently in use. The classification suggested here is intended to allow pathologists and clinicians to manage their patients with NENs consistently, while acknowledging organ-specific differences in classification criteria, tumor biology, and prognostic factors. The classification suggested is based on a consensus conference held at the International Agency for Research on Cancer (IARC) in November 2017 and subsequent discussion with additional experts. The key feature of the new classification is a distinction between differentiated neuroendocrine tumors (NETs), also designated carcinoid tumors in some systems, and poorly differentiated NECs, as they both share common expression of neuroendocrine markers. This dichotomous morphological subdivision into NETs and NECs is supported by genetic evidence at specific anatomic sites as well as clinical, epidemiologic, histologic, and prognostic differences. In many organ systems, NETs are graded as G1, G2, or G3 based on mitotic count and/or Ki-67 labeling index, and/or the presence of necrosis; NECs are considered high grade by definition. We believe this conceptual approach can form the basis for the next generation of NEN classifications and will allow more consistent taxonomy to understand how neoplasms from different organ systems inter-relate clinically and genetically.

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Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Fig. 1
Fig. 1
The H&E appearance of NEN from different sites: a a grade 1 NET from the ileum, b a grade 2 NET from the lung (atypical carcinoid), c a grade 3 NET from the pancreas, d a NEC (SCLC) from the lung, and e large cell NEC from the pancreas
Fig. 2
Fig. 2
Ki-67 staining of NEN from different sites: a a grade 1 NET from the ileum, b a grade 2 NET from the lung (atypical carcinoid), c a grade 3 NET from the pancreas, and d a NEC (SCLC) from the lung
See this image and copyright information in PMC

References

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