Endoscopic and histologic characteristics of serrated lesions

Table 1 Serrated polyps characteristics

	Hyperplastic polyps	Sessile serrated adenoma	Traditional serrated adenoma
Frequency among polyps	28 à 42%	9%	1%
Dominant sex	Male	Female	No ascendancy
Macroscopy
Size	< 5 mm	> 5 mm	> 5 mm
Paris classification	IIa	Is, IIa	Ip, Is
Localization	distal, rectum	proximal, 27% distal	distal
Pit pattern « Kudo »	II	II-O (Open)	II-IIIs or IIIL
Microscopy
Crypts	Serrated aspect on the superior half of the crypts	Upper third serrated aspect of crypts, horizontalization of the third inferior of crypts aspect of “boot” or L	Aspect serrated on all the crypt, ectopique crypts
Epithelium	Cylindrical	Important mucus, small nuclear modifications	tubulo-villous dysplasia (37%), carcinoma (11%)
Maturation, degenerative potential	Normal index of proliferation, no degenerative potential	Increased proliferative index with degenerative risk	Increased proliférative index with degenerative risk
Molecular	+/- Braf, Kras, MSI (29%)	Braf (82%), CIMP-H, méthylation MLH1	Kras (30%-80%), CIMP-L, méthylation MGMT

MSI: Microsatellites instability; CIMP-H, CIMP-L: CpG island methylation promotor-high, CIMP-bas; MLH1: MutL homolog 1; MGMT: MethylGuanine DNA methyltransferase.

Table 2 Endoscopic follow-up according to United States Multi-Society Task Force on Colorectal Cancer[39] and European Society of Gastrointestinal Endoscopy[40]

Serrated polyps	Follow-up according to United States multi-society[39]	Follow-up according to ESGE[40]
HP	5 yr, if > 10 mm or proximal	10 yr
SSA without dysplasia	< 3 lesions, < 1 cm: 5 yr	10 yr
	≥ 3, > 1 cm: 3 yr
SSA with dysplasia	3 yr	3 yr
TSA	3 yr	3 yr
Serrated polyposis	1 yr	1 yr

ESGE: European Society of Gastrointestinal Endoscopy; HP: Hyperplastic polyps; SSA: Sessile serrated adenomas.