Traditional serrated adenoma of the colorectum: clinicopathologic implications and endoscopic findings of the precursor lesions.
OBJECTIVE
To investigate the clinicopathologic and endoscopic features of precursor lesions associated with traditional serrated adenomas (TSAs).


METHODS
Mutation studies for BRAF, KRAS, PIK3CA, and EGFR and immunohistochemical staining for Ki-67 were performed on 107 TSAs from 104 patients.


RESULTS
Nondysplastic hyperplastic polyp (HP) or sessile serrated adenoma/polyp (SSA/P) precursor lesions were found in 56 (52.3%) TSAs, among which 32 (57.1%) cases showed a flat-elevated lesion with a type II pit pattern during endoscopy. TSAs with an SSA/P precursor lesion were usually found in the proximal colon, while TSAs with an HP or with no precursor lesion were mainly located in the distal colon and rectum (P < .001). TSAs with a precursor lesion showed a lower frequency of conventional epithelial dysplasia and KRAS mutation as well as a higher frequency of BRAF mutation compared with those with no precursor lesion (P = .002, P < .001, and P < .001, respectively).


CONCLUSIONS
A significant proportion of HP or SSA/P precursor lesions accompanied by TSAs can be detected by endoscopy based on both their flat-elevated growth and type II pit patterns. The heterogeneity of TSAs in terms of clinicopathologic and molecular features correlated with the status or type of precursor lesions.
Dept of Pathology, Daehang Hospital, 481-10 BangBae3-dong, Seocho-gu, 137-820, Seoul, South Korea; mjkimdoc@gmail.com.
Mi-Jung
MJ
Kim
Eun-Jung
EJ
Lee
Jung-Pil
JP
Suh
Sung-Min
SM
Chun
Se-Jin
SJ
Jang
Do Sun
DS
Kim
Doo Han
DH
Lee
Suk Hee
SH
Lee
Eui Gon
EG
Youk
D000236:Adenoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058534:Class I Phosphatidylinositol 3-Kinases; D003111:Colonic Polyps / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D004252:DNA Mutational Analysis; D016145:Endoscopy, Digestive System; D066246:ErbB Receptors / Q000235:genetics; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000096:biosynthesis; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D016133:Polymerase Chain Reaction; D011230:Precancerous Conditions / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics
C117307:KRAS protein, human; D019394:Ki-67 Antigen; D011518:Proto-Oncogene Proteins; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; C512478:EGFR protein, human; D066246:ErbB Receptors; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins
BRAF; Colon; Hyperplastic polyp; KRAS; Precursor; Serrated adenoma