colonic lipoma is the second most common , but very rare , tumor after colon polyps.1 although most cases are found incidentally in asymptomatic patients , some cases may present with symptoms such as abdominal pain , diarrhea , intestinal obstruction and bleeding .
the reported size of lipoma varies from 2 mm to 30 cm , with increased likelihood of having symptoms as the size is bigger.1 - 3 patients with a larger lesion or symptomatic patients require treatments .
surgical resection has been considered better suited for giant ( 2 cm ) lesions than endoscopic management , which is highly likely to cause complications such as perforation or bleeding in a giant lesion . with recent breakthrough in endoscopic excision technology , however , reports of successful endoscopic management is increasing even for giant lesions.4 - 6 two endoscopic methods to manage lipoma , complete resection and partial resection ( including unroofing technique ) , have been reported.7 - 9 the difference of effectiveness between these two methods is not proven,9 but partial resection is thought to be much safer than complete resection due to lower chances of complication .
now , we report our experiences of three cases of giant colon lipoma that were cleared up after partial resection , together with a literature review .
a 65-year - old female was referred to our center due to a giant colon lipoma detected on a colonoscopy .
a wide - based 33-cm size yellowish protruding mass without mucosal change was detected at the ileocecal valve during colonoscopy ( fig .
we planned to perform an unroofing technique with a snare catheter ( asm-1-s ; wilson - cook medical inc .
, winston - salem , nc , usa ) at the center of the lesion so that the remaining lipoma could flow out of the exposed surface .
it was deemed as appropriate to remove the roof of the center because the wide base of the lipoma could impede the conduction of electric current .
erbe icc 200 ( elektromedizin , tubingen , germany ) was used as the electrosurgical unit ; at the endo - cut mode ( 120 w , effect 3 ) , partial resection was performed twice , each time lasting for less than 5 seconds , to resect about half of the mass ( fig .
the patient was relieved of the abdominal discomfort afterwards . at 3-year follow - up colonoscopy ,
a 46-year - old female was referred to the center with a colonoscopic finding of 33 cm giant lipoma at the sigmoid colon during a health examination performed 3 years ago .
being asymptomatic , the patient had been followed on an outpatient basis but was referred to our center due to continued abdominal discomfort in the left lower quadrant .
a wide - based 33-cm yellowish globular mass without mucosal change was detected 30 cm above the anal verge during colonoscopy ( fig .
partial resection technique was performed with a snare catheter at the center of the lesion so that the remaining lipoma could flow out of the exposed surface ( fig .
since the mass was attached in a globular form , snare catheter was placed slightly apart from the base for optimal constriction . at the endo - cut mode ( 120 w , effect 3 )
, partial resection was performed for less than 10 seconds to resect most of the mass .
the colonoscopic finding at the next day confirmed flowing out of the remaining lipoma tissue at the exposed lesion ( fig .
the patient was relieved of the abdominal discomfort afterwards . at 1-year follow - up colonoscopy ,
a 48-year - old male was referred to the center with diagnosis of a benign lesion in the ascending colon detected by abdominal - pelvic computed tomography and abdominal discomfort in the right lower quadrant . at colonoscopy , a 47-cm cylindrical protruding mass without mucosal change was detected originating from the proximal ascending colon ( fig .
3a ) . as the size of the mass was much bigger than the other cases , we first tried partial resection with a snare catheter at the apical end of the mass unlike the other cases . at the endo - cut mode ( 120 w , effect 3 ) ,
partial resection was performed for 20 seconds unsuccessfully due to the impeded conduction of the electric current by the submucosal lipoma tissue ( fig .
it was found that the diameter of the mass became decreased toward the base of the cylindrical mass , which was why we retried partial resection slightly apart from the origin .
simulations were performed several times near the base of the mass , before performing the resection , in order to find the proper placement of the snare catheter with optimal constriction while avoiding possible thermal injury ( fig .
partial resection was performed for less than 5 seconds to reset most of the mass .
as observed from the resected specimen of the mass , the apical end of the mass was too thick to apply electric current without inflicting severe thermal injury on the adjacent tissues , while the actual resected part was relatively thinner and the electric current was well - applied with rare thermal injury on the adjacent tissues ( fig .
at 1-year follow - up colonoscopy , a surgical scar was observed but not any remaining lipoma .
a 65-year - old female was referred to our center due to a giant colon lipoma detected on a colonoscopy .
a wide - based 33-cm size yellowish protruding mass without mucosal change was detected at the ileocecal valve during colonoscopy ( fig .
we planned to perform an unroofing technique with a snare catheter ( asm-1-s ; wilson - cook medical inc .
, winston - salem , nc , usa ) at the center of the lesion so that the remaining lipoma could flow out of the exposed surface .
it was deemed as appropriate to remove the roof of the center because the wide base of the lipoma could impede the conduction of electric current .
erbe icc 200 ( elektromedizin , tubingen , germany ) was used as the electrosurgical unit ; at the endo - cut mode ( 120 w , effect 3 ) , partial resection was performed twice , each time lasting for less than 5 seconds , to resect about half of the mass ( fig .
the patient was relieved of the abdominal discomfort afterwards . at 3-year follow - up colonoscopy ,
a 46-year - old female was referred to the center with a colonoscopic finding of 33 cm giant lipoma at the sigmoid colon during a health examination performed 3 years ago .
being asymptomatic , the patient had been followed on an outpatient basis but was referred to our center due to continued abdominal discomfort in the left lower quadrant .
a wide - based 33-cm yellowish globular mass without mucosal change was detected 30 cm above the anal verge during colonoscopy ( fig .
partial resection technique was performed with a snare catheter at the center of the lesion so that the remaining lipoma could flow out of the exposed surface ( fig .
since the mass was attached in a globular form , snare catheter was placed slightly apart from the base for optimal constriction . at the endo - cut mode ( 120 w , effect 3 )
, partial resection was performed for less than 10 seconds to resect most of the mass . typical yellow tissue indicating lipoma
the colonoscopic finding at the next day confirmed flowing out of the remaining lipoma tissue at the exposed lesion ( fig .
the patient was relieved of the abdominal discomfort afterwards . at 1-year follow - up colonoscopy ,
a surgical scar was observed but not any remaining lipoma ( fig . 2f ) .
a 48-year - old male was referred to the center with diagnosis of a benign lesion in the ascending colon detected by abdominal - pelvic computed tomography and abdominal discomfort in the right lower quadrant . at colonoscopy , a 47-cm cylindrical protruding mass without mucosal change was detected originating from the proximal ascending colon ( fig .
3a ) . as the size of the mass was much bigger than the other cases , we first tried partial resection with a snare catheter at the apical end of the mass unlike the other cases . at the endo - cut mode ( 120 w , effect 3 )
, partial resection was performed for 20 seconds unsuccessfully due to the impeded conduction of the electric current by the submucosal lipoma tissue ( fig .
it was found that the diameter of the mass became decreased toward the base of the cylindrical mass , which was why we retried partial resection slightly apart from the origin .
simulations were performed several times near the base of the mass , before performing the resection , in order to find the proper placement of the snare catheter with optimal constriction while avoiding possible thermal injury ( fig .
partial resection was performed for less than 5 seconds to reset most of the mass .
as observed from the resected specimen of the mass , the apical end of the mass was too thick to apply electric current without inflicting severe thermal injury on the adjacent tissues , while the actual resected part was relatively thinner and the electric current was well - applied with rare thermal injury on the adjacent tissues ( fig .
the patient was relieved of the abdominal discomfort afterwards . at 1-year follow - up colonoscopy ,
generally , simple follow - up is sufficient for asymptomatic colon lipomas since they are highly unlikely to develop to malignancy.10 excision becomes a necessity , however , when the size of the lipoma gets as big as to require histologic examinations for differential diagnosis from other malignancies and the patient accompanies symptoms such as abdominal pain , constipation , bleeding , or intestinal obstruction.4,10,11 furthermore , ileocecal valve hypertrophy or lipomas occurring at the ileocecal valve , as presented in the case 1 , is believed to cause small bowel obstruction.12 recent development of endoscopic instruments and their accessories has enabled endoscopic excision of huge lipomas , but the complication rate is still higher than polypectomy.6 pfeil et al.11 performed endoscopic removal of colon lipoma in seven patients and reported perforation in three of them .
adipose tissue contains not enough water to facilitate conduction of electric current , which is why endoscopists apply higher electrical output for snare during procedure , causing thermal injury on the colon wall adjacent to the mass and increasing the likelihood of perforation.6,13 it seems that , in case of a pedunculatd type with a long stalk , it is relatively safe to perform a procedure , as if performing polypectomy , bearing the low conduction in mind .
however , in case of a wide - based lipoma , surgical resection is inevitable since forced endoscopic resection of such cases may not only cause acute complications such as bleeding or perforation , it may also lead to a severe stricture due to a large iatrogenic ulcer occurring after the resection.6 two endoscopic methods to manage lipoma , complete resection and partial resection ( including unroofing technique ) , have been reported.7 - 9 the unroofing technique , first reported by mimura et al.,7 is a new method of endoscopic resection for colorectal lymphangioma , a benign tumor composed of several interconnected cavities .
the unroofing technique only cuts off the upper half of the submucosal tumor , thus reducing the risk of complications .
the difference of effectiveness between the two methods is not proven,9 but partial resection is thought to be much safer than complete resection due to lower chances of complication .
however , in case of lipoma of big size ( like case 3 ) , remnant lipoma after cutting of the upper half could be possible .
therefore , in order to complete removal , more resection is more effective . in this report , we performed endoscopic partial resection for wide - based giant lipomas to facilitate spontaneous flowing out of the remaining tissues with time .
practical methods to apply this strategy in three patients with distinct shapes of giant lipomas were described in detail . in the case 1 , the patient had a wide - based lipoma . in order to expose the lesion by opening the cover ,
the partial resection of the central tissues was safely performed twice , and the remaining tissues were left to flow out spontaneously ( unroofing technique ) . in the case 2 , the lipoma was globular but wide - based , suggesting high risk of deep thermal injury on the adjacent tissues when resected in the form of polypectomy .
snare catheter was placed slightly apart from the base ensuring optimal constriction and the resection was performed for less than 10 seconds .
the examination on the next day revealed the lipoma tissues flowing out of the exposed surface . in the case 3 , we could personally witness the fact that snare resection of a giant lipoma could only lead to serious thermal injury on the adjacent tissues , suggesting high chance of complication after lipoma resection close to the base .
we prefer and recommend using higher power cutting mode with shorter coagulation time , which can minimize cutting time and reduce heat - induced damage of adjacent tissues .
but , in cases of polypectomy , polyps larger than 1 cm in the right colon or larger than 2 cm in the left colon and multiple polyps carried an increased risk of bleeding and perforation.14 therefore , we think that lipoma with a broad base or a large diameter has the risk for complication after endoscopic resection .
although surgery is not necessarily the first - line treatment option any more , the following circumstances are good candidates for operation ; in case with wide - base sessile lipoma , unclear diagnosis , intussusception or obstruction , involvement of muscular and serosal layers.15 in conclusion , endoscopic resection could be preferentially recommended for giant lipomas , provided that the lipoma was well - characterized and the procedure was applied safely .
the lesions could be cleared up spontaneously by unroofing technique and more aggressive resection will be needed in case of big size .
 colonic lipoma , a very rare form of benign tumor , is typically detected incidentally in asymptomatic patients . 
 the size of lipoma is reported variously from 2 mm to 30 cm , with higher likelihood of symptoms as the size is bigger . 
 cases with symptom or bigger lesion are surgically resected in principle ; endoscopic resection , which has developed recently with groundbreaking advance of endoscopic excision technology , is being used more often but with rare report of success due to high chance of complications such as bowel perforation or bleeding . 
 the authors report here , together with a literature review , our experiences of three cases of giant colonic lipomas showing complete remission after aggressive unroofing technique , at certain intervals , using snare catheter at the origin of the lipoma so that the remaining lipoma could be drained out of the exposed surface spontaneously , in order to reduce complications . 