ectopic gastric mucosa and polyps related to brunner 's gland hyperplasia are the most common polyps . serrated polyps are characterized by infolding of the crypt epithelium , resulting in a saw - tooth appearance . a polyp with serrated morphological features has been classified histologically as hyperplastic polyp in the past . until the late 1990s , colorectal polyps were generally divided into two major subtypes : hyperplastic polyps and adenomatous polyps . in 1990 , serrated came from the observation of the saw tooth - shaped infoldings of the surface and crypt epithelium of these polyps that was similar to that of hyperplastic polyps . serrated polyps are now classified into 3 distinct types by histologic and genetic characteristics : hyperplastic polyp , sessile serrated adenoma , and transitional serrated adenoma ( tsa ) . a serrated adenoma is a precursor lesion for colorectal carcinoma ( crc ) . the serrated neoplasia pathway has been associated with carcinogenesis of serrated adenoma , which is different from the traditional adenoma - carcinoma sequence [ 5 , 6 ] . serrated polyps are commonly found in the colorectum but have rarely been described in other parts of the gastrointestinal tract . because of the rarity of identifying such a lesion in the small bowel , the natural history , prognosis , and appropriate management recommendations are unclear . serrated adenomas in the small intestine may represent more aggressive lesions with high malignant potential than those in the colon and rectum , according to some reports . we should consider the existence of serrated adenoma of the duodenum and its higher virulence . we report a case of a slow - growing early adenocarcinoma arising from a traditional serrated adenoma of the duodenum , which was diagnosed and treated by an endoscopic mucosal resection . a 66-year - old man with no significant medical history underwent esophagogastroduodenoscopy ( egd ) for general examination ( fig .  1 ) . he had a 1-cm sized , yamada type iv polyp in the second portion of the duodenum . it was an elevated mucosal lesion with focal white patch and was located at the proximal site of the major papilla . the follow - up egd was done after 2 years ( fig .  2 ) . we recommended the patient to resect the polyp ; however , he preferred regular follow - up examination every year . there was no change in the shape , size , and pathologic finding of the polyp for two consecutive years . he underwent another egd for general medical check - up 3 years later ( 5 years after the first detection ) ( fig . the size of the polyp was slightly increased , but the shape of the polyp was not changed . the lesion was raised by means of a submucosal injection of hypertonic saline tinted with indigo carmine and resected by using a snare . the pathologic result revealed a 0.8  0.5-cm sized , well differentiated tubular adenocarcinoma ( fig .  5 ) . carcinomas are multifocally spread on the traditional serrated adenoma , and the proportion of adenocarcinoma component is approximately 50% . abdominal pelvic computed tomography and positron emission tomography showed no other solid organ involvement or metastasis . he is now in good health and we will perform surveillance follow - up egd after 1 year . benign serrated polyps are commonly found in the colorectum but have rarely been described in other parts of the gastrointestinal tract . histology disclosed an adenomatous growth with unlocked saw tooth - like glands with high - grade dysplasia . tsas were found in the esophagus , the stomach , the duodenum , the pancreas , and the gallbladder . increased awareness of the existence of serrated neoplasms in the upper digestive tract rubio 's   review indicated that 53.4% ( n = 39 ) of the 73 tsas of the upper digestive tract showed a simultaneously growing invasive carcinoma . following that original publication [ 13 , 14 , 15 ] , 35 additional cases of tsa of the duodenum appeared in the literature ; 28.6% ( n = 10 ) of the 35 cases showed invasive growth . of 73 cases of tsa of the upper digestive tract reported in the literature so far , 53.4% ( n = 39 ) had invasive carcinoma . although the causes for this aggressive behavior remains elusive , it would appear that not only the degree of cellular severity , but also the histological configuration ( i.e. , with unlocked serrations ) might have played a particular role in their virulence . in rosty et al 's study , high - grade dysplasia was present in six of the serrated adenomas ( 46% ) . one case was an adenocarcinoma resembling a serrated adenocarcinoma of the colorectum , with an adjacent serrated adenoma . this high frequency of high - grade dysplasia suggests that these adenomas may represent aggressive lesions with high malignant potential . serrated adenomas in the small intestine may represent a distinct morphological subtype of adenoma with a biological significance that is different from those in the colon and rectum . in the current case , it is consistent with other reports that serrated adenoma in the small bowel is more virulent than those in the colon . tsas of the duodenum should be radically excised , either endoscopically or surgically to rule out the possibility of a synchronously growing invasive adenocarcinoma or to prevent cancer progression . in conclusion , this present case distinctively showed a slow growth but had adenocarcinoma arising from serrated adenoma of the duodenum . we should consider the existence of serrated adenoma of the duodenum and excise it radically owing to its high virulence .
serrated polyps are classified into 3 distinct types : hyperplastic polyp , sessile serrated adenoma , or transitional serrated adenoma . a serrated adenoma is a precursor lesion for colorectal carcinoma . 
 serrated polyps are commonly found in the colorectum but have rarely been described in other parts of the gastrointestinal tract . serrated adenomas in the small intestine may represent aggressive lesions with high malignant potential , according to some reports . 
 a 66-year - old man with no significant medical history underwent esophagogastroduodenoscopy ( egd ) for general examination . 
 he had a 1-cm sized , yamada type iv polyp , with focal white patch in the second portion of the duodenum . 
 the biopsy result revealed gastric metaplasia and chronic inflammation . 
 he wanted regular follow -up examinations . 
 the follow - up egds were done every year . 
 there were no changes in the shape and size of the polyp . 
 the pathologic findings were unchanged . 
 then , he underwent egd for general medical check - up again 5 years after the first detection . 
 the size of the polyp was slightly increased . 
 the biopsy result revealed serrated polyp , unclassified . 
 endoscopic mucosal resection was done . 
 the pathologic result revealed a 0.8  0.5-cm sized , well differentiated tubular adenocarcinoma . 
 carcinomas are multifocally spread on the traditional serrated adenoma , and the proportion of the adenocarcinoma component is approximately 50% . 
 the tumor had invaded the lamina propria but confined to the mucosa . 
 the resection margins were negative , and no lymphovascular invasion or perineural invasion was seen . 
 abdominal pelvic computed tomography and positron emission tomography showed no other solid organ involvement or metastasis . 
 surveillance follow - up egds were done after 3 months and 1 year . 
 there was no evidence of recurrence .