WHO grade classification
World Health Organization grading system for neuroendocrine tumors based on proliferative activity and differentiation.
Full Definition
The WHO grade classification is the internationally accepted system for categorizing neuroendocrine tumors according to their biological behavior and clinical aggressiveness. The current system primarily uses proliferative indices, particularly Ki-67 labeling index and mitotic count, to assign grades ranging from G1 (low-grade, well-differentiated) to G3 (high-grade, poorly differentiated). This classification system has undergone several revisions, with site-specific criteria for different anatomical locations such as pancreas, lung, and digestive system. The WHO grade is crucial for determining prognosis, treatment selection, and clinical management of neuroendocrine neoplasms.
Usage
Usage note: Always specify the year of WHO classification when citing specific criteria, as these have been updated multiple times.
In Context
- "The pancreatic neuroendocrine tumor was classified as WHO grade 2 based on a Ki-67 index of 8%." — pathology report
- "Recent updates to the WHO grade classification have refined criteria for gastroenteropancreatic neuroendocrine tumors." — clinical guideline