Serrated pathway: Alternative route to colorectal cancer

Table 1 Most important features of serrated polyps[18,19,38,39,62]

	Sessile serrated adenoma	Traditional serrated adenoma	Hyperplastic polyps
Location	Proximal	Distal	Distal
Macroscopic characteristics	Sessile, flat, covered with mucus, poorly defined borders	Protruding, pedunculated	Flat
Color	Normochromatic, pale	Reddish	Pale
Size	> 5 mm	> 5 mm	< 5 mm
Molecular features	BRAF mt	KRAS mt
Histological characteristics	Dilated, branched serrated crypts at the bottom	Prominent crypt serration, ectopic crypt formation	Serrations at the top
Pit pattern	Open-shape (type II-O)	Fern or pinecone-like	Starlike (type II)
Precursor	MVHP	GCHP	ACF
Malignant potential	+++	++	-
CIMP status	CIMP-H	CIMP-L
MSI status	MSI-H or MSS	MSI-L or MSS	MSS
Gender predominance	Female	Male	Male
Dysplasia	Absent	Present	Absent
Ectopic crypt formation	Absent	Present	Absent

MVHP: Microvesicular hyperplastic polyp; GCHP: Goblet cell-rich hyperplastic polyp; ACF: Aberrant crypt focus; CIMP-H: CpG island methylator phenotype-high; CIMP-L: CpG island methylator phenotype-low; MSI-H: High-level microsatellite instability; MSI-L: Low-level microsatellite instability; MSS: Microsatellite stable.

Table 2 Colonoscopic management and surveillance strategies for serrated polyps based on experts’ opinion and current literature[28,34,51,63]

Serrated polyp	Intervention	Surveillance interval
Hyperplastic polyp in the rectosigmoid	No surveillance recommended	Screening colonoscopy at 10 yr
SSA without dysplasia	Endoscopic resection (EMR)	< 3 lesions, < 1 cm: 5 yr
		≥ 3 lesions, ≥ 1 cm: 3 yr
SSA with dysplasia	Endoscopic resection (EMR)	Complete: 2-6 mo
		Incomplete: Segmental colectomy
TSA	Endoscopic resection (cold-snare)	Complete: 3 yr
		Incomplete: Segmental colectomy
Serrated polyposis	Endoscopic resection	Follow-up colonoscopy at 6-12 mo
		Children: screening at an age 10 yr younger than index case
Serrated polyposis in first-degree relative	Screening at an age 10 yr younger	Follow-up colonoscopy at 12 mo

SSA: Sessile serrated adenoma; TSA: Traditional serrated adenoma; EMR: Endoscopic mucosal resection.