Dong Kyung Chang

Eun Ran Kim

Clinical Endoscopy

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Copyright © 2018 Korean Society of Gastrointestinal Endoscopy  313
COMMENTARY
Clin Endosc  2018;51:313-314
https://doi.org/10.5946/ce.2018.108
Print ISSN 2234-2400 • On-line ISSN 2234-2443
Open Access
Interval colorectal cancer (CRC) is defined as CRC diag-
nosed after a negative screening or surveillance colonoscopy 
(no cancer detection) and before the next recommended fol-
low- up examination.1 It has been generally accepted that most 
CRCs are derived from adenomatous polyps. Therefore, if an 
adenomatous polyp is detected and removed during a regu-
lar colonoscopy, the development of CRC can be prevented. 
Actually, previous studies have shown that the colonoscopic 
removal of adenomatous polyps reduces the mortality from 
CRC.2 However, interval CRCs have been consistently report-
ed in patients who have undergone a complete colonoscopy.3,4 
There are several explanations for the development of inter-
val CRCs including: missed lesions, new lesions, and incom-
plete resected lesions.5 Recent studies have reported that inter-
val CRCs exhibit some characteristics such as a predominant 
proximal location, association with the CpG island methylator 
phenotype (CIMP), and microsatellite instability.5,6 Further, 
these characteristics of interval CRCs overlap with sessile 
serrated adenomas/polyps (SSA/Ps). In recent years, there has 
been a growing interest in SSA/Ps. 
Although only 20% of serrated polyps are SSA/Ps, SSA/
Ps are considered more important than the other serrated 
polyps due to their malignant potential. SSA/Ps have been 
recognized as precursors of CIMP-positive and BRAF mutant 
CRCs that are often associated with microsatellite instability.7,8 
Unfortunately, the diagnosis of SSA/Ps is easy to miss due 
to their indistictive endoscopic morphologies. According to 
recent studies, the detection of SSA/Ps correlates with the gas-
troenterologist’s experience and skills.9 Therefore, it is crucial 
to know about the endoscopic features of SSA/Ps. Previous 
studies have reported that SSA/Ps exhibit presence of several 
endoscopic characteristics such as a mucous cap, a rim of de-
bris or bubbles, an alteration of the contour of a mucosal fold, 
the obscuring of an underlying submucosal vessel, a nodular 
surface and a dome-shaped protuberance.10,11 Following anal-
ysis of 158 SSPs, Tadepalli et al. reported that a mucous cap 
(63.9%) and peripheral rim (51.9%) were the most common 
characteristics of SSPs; further, these chracteristics showed a 
remarkable positive association with SSPs (odds ratio [OR] 3.8, 
p=0.0002).10 Murakami et al. showed that 95%–100% of SSA/
Ps with or without dysplasia had a mucous cap.12 
In a current issue of Clinical endoscopy, Moy et al. investi-
gated whether a mucous- capped polyp, one of the most com-
mon endoscopic features of SSA/Ps, can predict the presence 
of serrated polyps.13 They examined the endoscopic features 
of 147 mucous-capped polyps to determine if they could 
predict SSA/Ps. Among these, there were 127 (86%) serrated 
polyps (right-sided hyperplastic polyps, SSA/Ps, or traditional 
serrated adenomas), and only 43 (29%) SSA/Ps.13 To find the 
predictive features of SSA/Ps, they also evaluated other endo-
scopic characteristics of mucous- capped polyps such as polyp 
size (≥10 mm), the distinct border, elevation, rim of debris, 
location, varicos vessels, nodular surface and alterations in the 
Received: June 23, 2018    Accepted: July 6, 2018
Correspondence: Dong Kyung Chang
Division of Gastroenterology, Department of Internal Medicine, Samsung 
Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, 
Gangnam-gu, Seoul 06351, Korea
Tel: +82-2-3410-3409, Fax: +82-2-3410-6983, E-mail: dkchang@skku.edu
ORCID: https://orcid.org/0000-0001-8925-4629
cc  This is an Open Access article distributed under the terms of the Creative 
Commons Attribution Non-Commercial License (http://creativecommons.org/
licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, 
and reproduction in any medium, provided the original work is properly cited.
How to Detect Sessile Serrated Adenoma/Polyps
Eun Ran Kim and Dong Kyung Chang
Division of Gastroenterology, Department of Internal Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea
See “Endoscopic Features of Mucous Cap Polyps: A Way to Predict Serrated Polyps” by Brian T. Moy, Faripour Forouhar, Chia-Ling 
Kuo, et al., on page 368-374.
314   
fold contour. It was observed that 39 polyps of 43 SSA/Ps (91%) 
and 56 polyps of 104 non SSA/Ps (54%) were combined with 
varicos vessels, and these results were found to be statistically 
significant (adjusted OR, 10.75; p=0.000). Based on these find-
ings, the researchers concluded that mucous- capped polyps 
are more likely to be serrated polyps and the presence of a 
mucous cap combined with varicous vessels was a significant 
predictor for SSA/Ps. 
This study revealed some interesting results; however, these 
results should be interpreted with caution. 
Although previous studies have shown that most SSA/Ps 
had a mucous cap, this study demonstrated that most mu-
cous- capped polyps were unfortunatly not SSA/Ps (43/147, 
29%). Additionaly, while most mucous- capped SSA/Ps had 
varicous vessels (39/43, 91%), the percentage of SSA/Ps among 
mucous- capped polyps with varicous vessels was only 41% 
(39/95). Therefore, it is insufficient to conclude that the com-
bind presence of a mucous cap and varios vessels is a pre-
dictor for SSA/Ps. Additionally, there exists a possibility that 
further analysis according to the number of morphological 
characteristics of mucous capped polyps would provide more 
information and better predictability for SSA/Ps. 
Recent studies have attempted to identify the morphologi-
cal characteristics of SSA/Ps using several advanced imaging 
techniques such as narrow band imaging (NBI), image en-
hanced endoscopy or autofluorescence imaging.7,14 According 
to a recent meta-analysis, most of studies conducted using 
NBI and NBI proved to have a higher sensitivity for detecting 
SSA/Ps compared to other endoscopic imaging techniques.15 
However, the sensitivity of NBI for detecting SSA/Ps has 
shown variations, depending on the endoscopic features. For 
example, indistinct borders (OR, 3.7) and a cloud-like surface 
(OR, 2.65) were found to be associated with SSA/Ps on high- 
resolution white light, whereas on an NBI, a cloud-like surface 
(OR, 4.91), indistinctive borders (OR, 2.38) and dark spots 
inside the crypts (OR, 2.05) were correlated with SSA/Ps.11 
Based on current studies, there are no clear and definite en-
doscopic features to predict serrated lesions, especially SSA/Ps. 
However, in general practice, it is paramount to make efforts 
not to miss the serrated polyps. This can be accomplished 
by gaining an in-depth knowledge of the several endoscopic 
characteristics of serrated polyps and conducting a meticulous 
examination of the bowel mucosa.  
Conflicts of Interest
The authors have no financial conflicts of interest.
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