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villous tumor of the colon is a lesion with an apparently villous surface and is diagnosed macroscopically .
the area of predilection for villous tumor of the colon is the sigmoid colon and the rectum , and histologically the tumor is villous or tubulovillous adenoma and may be partly complicated by carcinoma .
electrolyte disorders ( loss of sodium , potassium and chloride ) , caused by the large amount of mucous diarrhea from giant villous tumors , are called electrolyte depletion syndrome .
it is said that a large quantity of mucinous secretion and reabsorption disorder may cause electrolyte disorder .
villous tumors with electrolyte depletion syndrome are often 10 cm in size and nearly circumferential .
because of their size , colon / rectal resection after correction of the electrolyte disorder is performed .
there has been no report of endoscopic resection of villous tumors with electrolyte depletion syndrome .
we successfully treated a patient with a circumferential villous tumor of the rectum causing electrolyte depletion syndrome by endoscopic submucosal dissection ( esd ) .
she consulted a local physician in february 2013 due to diarrhea . since general fatigue and
a body weight loss of 3 kg within 5 months were observed , she was admitted for detailed examination and treatment . on blood tests ,
blood urea nitrogen was 58.7 mg / dl and creatinine was 1.02 mg / dl , indicating kidney dysfunction ; sodium was 126
colonoscopy revealed a circumferential laterally spreading tumor with a maximum diameter of 10 cm in the rectum .
since biopsy findings indicated villous adenoma , the patient was referred to our hospital for endoscopic treatment . on admission
the electrolyte levels had been corrected by the previous physician and were in the normal ranges .
colonoscopy revealed a circumferential villous tumor of the rectum with a maximum diameter of 10 cm ( fig .
narrow - band imaging magnifying endoscopy revealed meshed capillary vessels , and the tumor was classified as type iiia .
it secreted a large amount of mucus , and a diagnosis of electrolyte depletion syndrome causing electrolyte disorders was made .
since submucosal invasion was judged to be negative , sufficient informed consent was obtained from the patient and her family , and esd was carried out in late june .
after about 12 h ( 727 min ) , when about half of the tumor had been dissected , esd was temporarily suspended in consideration of the stress to the patient and concentration of the endoscopist . on the next day , esd could not be continued because there was no vacancy in the schedule of the endoscopy room .
esd was resumed on the following day , 36 h after its suspension , and the tumor was removed en bloc with dissection of the remaining half ( fig .
since circumferential dissection was performed , steroid ( triamcinolone acetonide ) was topically injected into the submucosa as a measure to prevent stenosis .
histopathological examination revealed that the resected specimen was a circumferential tumor measuring 12.7  11.5 cm and was mostly tubulovillous adenoma , but partially moderately differentiated adenocarcinoma .
the histopathological diagnosis was well - differentiated adenocarcinoma in high - grade adenoma located in the lower to upper rectum , invading into the mucosa without lymphatic or venous invasion , with a stump negative for adenocarcinoma and positive for adenoma .
oral nutrition was resumed on the 2nd postoperative day , and the patient was discharged on the 8th postoperative day .
after discharge , general fatigue and diarrhea present before esd disappeared , and electrolyte disorders resolved ( table 1 ) .
colonoscopy 4 months after esd showed shrinking of the dissected surface , and no marked constriction or remnant of the tumor was noted ( fig .
on colonoscopy 12 months after esd , the dissected surface was covered by regenerated mucosa , and no recurrence or stenosis was noted ( fig .
according to the definition by muto and adachi , villous tumor of the colon is a lesion with an apparently villous surface and is diagnosed macroscopically .
histologically , the tumor is villous or tubulovillous adenoma and may be partly complicated by carcinoma .
electrolyte disorders caused by mucous diarrhea are called electrolyte depletion syndrome and were first reported in 1954 by mckittrick and wheelock .
the frequency of electrolyte disorders caused by villous tumor is 0.762.4% , and the condition is relatively rare [ 5 , 6 ] .
sasaki et al .   reported ( 1 ) frequent occurrence in elderly people , ( 2 ) long duration of illness , ( 3 ) frequent involvement of the rectum or sigmoid colon , ( 4 ) frequent extension to a length of 10 cm , ( 5 ) marked diarrhea and ( 6 ) frequent complication by carcinoma as characteristics of villous tumor of the colon causing electrolyte depletion syndrome .
reviewed 64 japanese cases in the literature and reported that villous tumors were large , with a maximum diameter of 426 cm ( mean 13.9 cm ) , were nearly circumferential and were complicated by carcinoma in 72.4% of those who developed electrolyte depletion syndrome . concerning treatment , complete resection of the tumor
is necessary after the correction of dehydration and electrolyte disorders , but the disease is often mucosal tumor or shows no complicating carcinoma , and there is a report that a procedure similar to that for advanced colon cancer may be overtreatment . in our patient ,
carcinoma was not detected by biopsy , and esd was performed as a less invasive procedure .
esd is a treatment that permits en bloc resection of large lesions , which used to be difficult to resect endoscopically , and allows detailed histopathological evaluation [ 9 , 10 ] .
there have been reports of esd performed for lesions > 10 cm in diameter [ 11 , 12 , 13 ] .
also , stenosis has been reported to occur less frequently even after circumferential dissection of the colon by esd because of the intraintestinal pressure and peristalsis .
administered betamethasone suppositories at 1 mg / day for two rectal lesions for 8 weeks after circumferential dissection and reported no marked postoperative stenosis .
however , yamada et al .   reported that they treated a patient with an upper rectum to rectosigmoid circumferential laterally spreading tumor 10 cm in diameter by esd , noted stenosis on the 23rd postoperative day and performed endoscopic balloon dilatation . in our patient
, we administered steroid ( triamcinolone acetonide ) topically to the submucosa after dissection as a measure to prevent stenosis , followed by a 4-month treatment with steroid suppositories , and could avoid stenosis .
therefore , after circumferential dissection , it is considered useful to prophylactically administer steroid with short - term observation and attempt endoscopic balloon dilatation if stenosis is observed .
mitani et al .   evaluated 34 patients who underwent extensive esd of a tumor 10 cm in maximum diameter and observed that esd , which is less invasive than surgical resection , is also advantageous for functional preservation , because the endoscope could be manipulated readily in the rectum , the risk of peritonitis due to perforation was low and colostomy could be avoided . in our patient , esd extended over 2 days , but the lesion could be completely resected without the need to construct a stoma .
postoperatively , electrolyte disorders were resolved , symptoms were alleviated , and no recurrence of cancer or stenosis was noted .
it is still necessary to improve the technique of esd in order to shorten the time needed for the procedure .
however , less invasive treatment by esd should still be considered for colorectal adenoma and mucosal carcinoma , even if the procedure takes a long time . in conclusion ,
a patient with a large colorectal carcinoma showing electrolyte depletion syndrome was successfully treated by esd without recurrence or stenosis .
an 81-year - old female consulted a local physician due to diarrhea . 
 since general fatigue and body weight loss were observed , she was admitted for detailed examination and treatment . 
 colonoscopy revealed a circumferential giant tumor with a maximum diameter of 10 cm in the rectum , and biopsy findings indicated villous adenoma . 
 the tumor secreted a large amount of mucus , and a diagnosis of electrolyte depletion syndrome causing electrolyte disorders was made . 
 we performed endoscopic submucosal dissection ( esd ) as a less invasive procedure . 
 the tumor was so big that the procedure had to be completed in two separate steps and it took 1,381 min in total . 
 the tumor was histologically diagnosed as well - differentiated adenocarcinoma in high - grade adenoma located in the lower to upper rectum , invading into the mucosa without lymphatic or venous invasion . 
 the stump of the resected specimen was negative for adenocarcinoma , however the horizontal stump was positive for adenoma . 
 we administered steroid suppositories to prevent stenosis . 
 after esd , general fatigue and diarrhea disappeared and electrolyte disorders resolved . 
 the patient had good clinical outcome without recurrence or stenosis .