colorectal cancer ( crc ) is one of the most common cancers in the world .
crcs usually progress from adenomatous polyps , and the morphological and genetic progression of crcs in an adenoma - adenocarcinoma sequence has been well described.1,2 a hyperplastic polyp ( hp ) is the most common histological type found among colorectal polyps , but they have been considered to have no malignant potential . however , recent studies have demonstrated that some hps can develop into crcs , especially in patients diagnosed with hyperplastic polyposis syndrome ( hps).3,4 recent studies have proposed that hps arising in hps progress toward adenocarcinoma through a " serrated neoplastic pathway " and that a b type raf kinase ( braf ) proto - oncogene mutation is one of the early genetic events in the initiation of this serrated pathway.4 - 6 
 braf mutations have recently been found in 5% to 15% of crcs.7 - 9 we present a case of a 34-year - old young woman with hps who had a braf mutation .
she had no family or personal history of colorectal carcinoma or other bowel diseases . however , she underwent a fine - needle aspiration biopsy ( fnab ) for incidentally discovered thyroid nodules 2 months previous .
her complete blood count showed no abnormal findings , and other laboratory tests and thyroid function tests were within the normal range .
0.2 to 0.7-cm - sized polyps were seen in the body and antrum of the stomach ( fig .
however , no lesions were observed in the bulb or secondary portion of the duodenum . during the colonoscopy , numerous 0.2 to 1.0-cm - sized polyps
we removed 48 and 70 polyps from the stomach and colorectum , respectively . a histological examination of the resected polyps revealed hps ( fig .
we performed a braf and k - ras mutation analysis as well as a microsatellite analysis on the representative hps of the colon .
was a missense mutation at codon 600 , exon 15 replacing gtg ( valine ) with gag ( glutamic acid ) .
a k - ras mutation and microsatellite instability ( msi ) , however , were not detected .
sporadic hps are of a benign nature and are usually small in size , multiply , increase with old age , and are mainly distributed in the sigmoid colon and rectum .
however , crcs arising in colorectal hps or serrated adenomas ( sas ) , especially in patients diagnosed with hps have been reported.10 - 14 additionally , recent studies proposed the hp - sa - carcinoma sequence as an alternative pathway for colorectal carcinogenesis.4,15,16 hps is an uncommon syndrome characterized by a diverse range of polyp types including multiple , large hps and smaller numbers of sas , traditional adenomas , and admixed hyperplastic / adenomatous polyps in the colon and rectum . in the world health organization ( who ) hps diagnostic criteria , burt and jass17 defined hps as at least five histologically diagnosed hps occurring proximal to the sigmoid colon and of which more than two are greater than 1 cm in diameter , or more than 30 hps in the whole colon and rectum , or any number of hps proximal to the sigmoid colon in an individual who has a first - degree relative diagnosed with hps . in such patients , polyps
are usually sessile and 1 - 7 mm in diameter , but larger and/or pedunculated hps may also be observed .
some patients had adenomas or crcs.18 - 20 hps of hps progress to crcs through the serrated pathway and a braf mutation is a key genetic event in the initiation of the serrated neoplastic pathway in the development of crc.4 - 6 the risk of malignant changes in hps seems much higher when the hps have histologically dysplastic features such as admixed polyps and sas or when they are large , numerous , located on the right - sided colon , and present in younger patients.21,22 genetic and epigenetic alterations in colorectal carcinoma are present in hps .
these alterations in clude braf or k - ras protooncogene mutations and msi.14,23,24 
 braf makes a protein called b - raf which is one of the members of the raf family of serine/ threonine kinases .
b - raf mediates cellular responses to growth signals through the ras - raf - mek ( mitogen - activated protein / extracellular signal - regulated kinase)-erk ( extracellular signal - regulated kinase)-map ( mitogen - activated protein ) kinase pathway.25,26 
 braf mutations have been found in various human cancers including crcs and melanomas.7,9,27 - 30 they have also been found in sporadic hps and in sas from patients with hyperplastic polyposis.6,31,32 
 braf mutations are frequent in crcs with a high level of msi , but uncommon in microsatellite - stable crcs.27 - 30 the frequency of braf mutations is much higher in hps , especially younger patients and patients with large and right - sided polyps than in sporadic hps which are predominantly present in the left - sided colon or rectum.23 in contrast , k - ras mutations are infrequent in hps , but frequent in sporadic hps.14 unlike braf , k - ras mainly plays a key role in the development of crc through the classical adenoma - adenocarcinoma sequence , allowing the growth and progression of adenomatous colorectal polyps.33 some reports have demonstrated that braf and k - ras mutations are strongly inversely correlated.7 - 9 it is rare that both braf and k - ras mutations are present in different polyps from the same patient.24 therefore , molecular data such as braf or k - ras can help in diagnosing hps . in our case ,
the 34-year - old young woman had 48 and 70 0.2 to 1.0-cm - sized hps in the stomach and large bowel respectively .
a case of hps identified with a braf mutation has been reported in only one case in korea until now.34 furthermore , hps with multiple gastric hps is very rare .
we think that genetic alterations such as braf mutations in hps may be frequently seen in patients who have hyperplastic polyposis in the stomach , colorectum or both .
although our case had no adenomatous or malignant changes , such patients may more frequently be accompanied with adenomatous or malignant changes in polyps .
because hps with a braf mutation may carry a high risk for crc , colonoscopic surveillance should be indicated .
endoscopic surveillance is recommended every 1 to 3 years for patients with hyperplastic polyposis.18 this endoscopic surveillance interval may be modified by other risk factors such as age , family or personal history of crc , histology of polyps , and genetic mutations such as braf , and so on.35
 hyperplastic polyposis syndrome ( hps ) is a rare condition characterized by the presence of numerous hyperplastic polyps ( hps ) in the colon and rectum . 
 patients with hps have an increased risk of colorectal cancer . this link is associated with gene mutations , especially b type raf kinase ( braf ) . however , a case of hps associated with gene mutations has seldom been reported in korea . here 
 , we describe a case of hps in which a braf mutation was present in a 34-year - old woman . 
 she had more than 110 hps in the stomach and colorectum , which we removed . 
 all of the polyps were diagnosed histologically as hps , and no adenomatous or malignant changes were noted . 
 we performed a braf and k - ras mutation analysis as well as a microsatellite analysis on the resected colon polyps . 
 braf mutations were found in the resected colon polyps , but there was no evidence of k - ras mutation or microsatellite instability . 
INTRODUCTION
CASE REPORT
DISCUSSION