Histopathology of NET: Current concepts and new developments

Area of Science:

• Oncology
• Pathology
• Histopathology

Background:

• Neuroendocrine tumors (NET) diagnosis depends on histopathologic appearance and immunohistochemical markers.
• The World Health Organization (WHO) 2010 classification introduced formal staging and grading for gastro-entero-pancreatic NET.
• Nomenclature for lung neuroendocrine tumors still commonly uses the term 'carcinoid'.

Purpose of the Study:

• To review the current diagnostic landscape of neuroendocrine neoplasms (NEN).
• To discuss the evolution of classification and nomenclature in NEN.
• To highlight key areas of controversy and focus in NEN histopathology.

Main Methods:

• Literature review of diagnostic criteria and classifications for NEN.
• Analysis of WHO 2010 guidelines for gastro-entero-pancreatic NET.
• Examination of current nomenclature practices for lung neuroendocrine tumors.

Main Results:

• The diagnosis of NEN is primarily based on histomorphology and immunohistochemistry.
• Formal staging and grading are established for gastro-entero-pancreatic NET under WHO 2010, but lung NEN nomenclature remains varied.
• The review addresses neuroendocrine carcinoma of unknown primary, tissue biomarkers, and histopathologic controversies.

Conclusions:

• Accurate diagnosis and classification of NEN are crucial for patient management.
• Standardization of nomenclature and grading across different NEN sites is an ongoing challenge.
• Further research into biomarkers and histopathologic nuances will refine NEN diagnosis and treatment.