Skip to main content
. 2020 May 21;26(19):2305–2322. doi: 10.3748/wjg.v26.i19.2305

Table 4.

Several editions of World Health Organization (pathological classification)

Edition Grading standards
2000/2004 G1: Well-differentiated NET; ≤ 2 cm in size, Ki-67 ≤ 2% G2: Well-differentiated NEC; > 2 cm in size, Ki-67 3%-20% or angioinvasive G3: Poorly differentiated NEC; Ki-67 > 20%
2010 NET-G1: Well-differentiated, mitotic count < 2/2 mm2, Ki-67 ≤ 2% NET-G2: Well-differentiated, mitotic count 2-20/2 mm2, Ki-67 3%-20% NEC-G3: Poorly differentiated, mitotic count > 20/2 mm2, Ki-67 > 20%
2017/2019 NET-G1: Well-differentiated, mitotic count < 2/2 mm2, Ki-67 ≤ 2% NET-G2: Well-differentiated, mitotic count 2-20/2 mm2, Ki-67 3%-20% NET-G3: Well-differentiated, mitotic count > 20/2 mm2, Ki-67 > 20% NEC-G3: Poorly differentiated, mitotic count > 20/2 mm2, Ki-67 > 20%

NET: Neuroendocrine tumor; NEC: Neuroendocrine carcinoma.