the conventional surgery for curative treatment of distal gastric cancer is resection of the distal stomach with all of the greater omentum and lesser omentum . but
a less invasive procedure such as laparoscopic - assisted distal gastrectomy ( ladg ) has become more popular as the detection rate of early gastric cancer has increased as a result of widespread regular check - ups .
laparoscopic surgery has become more popular as a minimal invasive procedure and it has been well demonstrated to have the advantages of a more favorable clinical course and lower mortality and morbidity , and especially for early gastric cancer patients ( 1 , 2 ) . as for the techniques , ladg and conventional open gastrectomy are the same for the extent of gastrectomy and lymph node ( ln ) dissection .
but unlike conventional open gastrectomy , the greater omentum is resected about 4 - 5 cm away from the greater curvature in ladg ( 2 ) .
the reasons are as follows : the possibility of omental metastasis is very low because the majority of patients who undergo ladg have early gastric cancer , and complete resection of the bulky greater omentum is technically difficult in the restricted space .
partial omentectomy is sometimes performed during open distal gastrectomy ( odg ) because of the low potential for omental metastasis in patients with early gastric cancer and to save the operation time required for complete removal of the omentum .
as odg and ladg with partial omentectomy are now being widely performed in korea and japan , it has increased the potential for omental infarction following partial omentectomy .
yet there are no radiologic studies or case reports of omental infarction following odg and ladg with partial omentectomy for gastric cancer .
so , we describe here the clinical features and computed tomography ( ct ) findings of omental infarction following partial omentectomy in open and laparoscopic - assisted distal gastrectomy and the differential diagnostic points from omental metastasis according to these two cases .
a 65-year - old woman underwent odg with partial omentectomy and d1 +  lymph node dissection [ dissection of the group 1 nodes plus the left gastric artery , the anterior common hepatic artery and the celiac artery nodes .
the grouping of lns is according to the japanese classification for gastric carcinoma ( jcgc ) staging system by the primary location of cancer . ]
her past medical history was diabetic mellitus and hypertension for several years that were controlled with medication and she underwent endoscopic submucosal resection ( esr ) three times for gastric polyps .
this patient was obese with a body mass index ( bmi ) 34.8 kg / m ( an initial weight of 81.4 kg and a height of 153.2 cm ) .
contrast enhanced abdominal ct and f - fluorodeoxyglucose ( fdg ) positron emission tomography - computed tomography ( pet - ct ) were routinely performed to evaluate tumor recurrence at six months after surgery . on the contrast enhanced axial ct scan ,
an ill - defined area of haziness with hyperattenuating streaky infiltration was seen in the remnant great omentum at the left subphrenic space and lateral to the stomach ( fig .
but it could be differentiated from carcinomatosis peritonei clinically because the lesion was locally confined to the remnant greater omentum and it was found in an early gastric cancer patient . in addition , the f - fdg pet - ct scan showed no abnormal fdg uptake at the same lesion ( fig .
six months after that , the follow up contrast enhanced ct scan revealed a decrease in the lesion size and there was progression from an ill - defined , heterogeneous fat density lesion to a well - defined , smaller lesion with a hyperdense rim at the left subphrenic space ( fig .
a 68-year - old woman underwent ladg with partial omentectomy and d1 +  lymph node dissection for early gastric cancer localized in the submucosa ( t1bn1m0 ) .
her past medical history was atrial fibrillation and parkinson 's disease for several years and these maladies were controlled with medication .
this patient was thin with a bmi 19.7 kg / m ( the initial weight of 50.4 kg and a height of 160 cm ) . on postoperative day 10 , she developed localized right upper quadrant pain with leukocytosis of 17,090/mm .
she had no fever , chills or gastrointestinal symptoms such as nausea , vomiting or diarrhea other than the right upper quadrant pain .
contrast enhanced abdominal ct was performed to differentiate the causes of her acute abdominal pain .
the enhanced ct scan revealed a 4 cm sized heterogeneous fat density mass with a peripheral enhancing rim and streaky infiltration in the omentum at the anterior to the pancreas head , which was a reasonable finding of omental infarction ( fig .
after five days , her symptoms disappeared completely and she was discharged from the hospital .
after five months , she was followed up with ct and f - fdg pet - ct .
the previously noted lesions had almost resolved and there was no abnormal fdg uptake except only mild omental haziness ( fig .
a 65-year - old woman underwent odg with partial omentectomy and d1 +  lymph node dissection [ dissection of the group 1 nodes plus the left gastric artery , the anterior common hepatic artery and the celiac artery nodes .
the grouping of lns is according to the japanese classification for gastric carcinoma ( jcgc ) staging system by the primary location of cancer . ]
her past medical history was diabetic mellitus and hypertension for several years that were controlled with medication and she underwent endoscopic submucosal resection ( esr ) three times for gastric polyps .
this patient was obese with a body mass index ( bmi ) 34.8 kg / m ( an initial weight of 81.4 kg and a height of 153.2 cm ) .
contrast enhanced abdominal ct and f - fluorodeoxyglucose ( fdg ) positron emission tomography - computed tomography ( pet - ct ) were routinely performed to evaluate tumor recurrence at six months after surgery . on the contrast enhanced axial ct scan ,
an ill - defined area of haziness with hyperattenuating streaky infiltration was seen in the remnant great omentum at the left subphrenic space and lateral to the stomach ( fig .
but it could be differentiated from carcinomatosis peritonei clinically because the lesion was locally confined to the remnant greater omentum and it was found in an early gastric cancer patient . in addition , the f - fdg pet - ct scan showed no abnormal fdg uptake at the same lesion ( fig .
six months after that , the follow up contrast enhanced ct scan revealed a decrease in the lesion size and there was progression from an ill - defined , heterogeneous fat density lesion to a well - defined , smaller lesion with a hyperdense rim at the left subphrenic space ( fig .
a 68-year - old woman underwent ladg with partial omentectomy and d1 +  lymph node dissection for early gastric cancer localized in the submucosa ( t1bn1m0 ) .
her past medical history was atrial fibrillation and parkinson 's disease for several years and these maladies were controlled with medication .
this patient was thin with a bmi 19.7 kg / m ( the initial weight of 50.4 kg and a height of 160 cm ) . on postoperative day 10 , she developed localized right upper quadrant pain with leukocytosis of 17,090/mm .
she had no fever , chills or gastrointestinal symptoms such as nausea , vomiting or diarrhea other than the right upper quadrant pain .
contrast enhanced abdominal ct was performed to differentiate the causes of her acute abdominal pain .
the enhanced ct scan revealed a 4 cm sized heterogeneous fat density mass with a peripheral enhancing rim and streaky infiltration in the omentum at the anterior to the pancreas head , which was a reasonable finding of omental infarction ( fig .
after five days , her symptoms disappeared completely and she was discharged from the hospital .
after five months , she was followed up with ct and f - fdg pet - ct .
the previously noted lesions had almost resolved and there was no abnormal fdg uptake except only mild omental haziness ( fig .
omental infarction is the end result of impaired perfusion to the greater omentum , and this is a rare disease entity that can cause acute or subacute abdominal pain in adults ( 4 ) .
the cause of primary idiopathic omental infarction is unknown , but it may be related to obesity , local trauma , occupational vibration , heavy food intake , excessive exercise and the use of laxatives .
obesity causes irregularly distributed accumulations of excess omental fat and the increased fat deposits outstrip the blood supply to the thickened omentum .
secondary omental infarction can be induced by various causes : torsion due to adhesion between the omentum and pathologic foci such as surgical scars , inflammation , cysts and tumors , thrombosis due to hypercoagulopathy and vascular abnormalities and congestion of the mesenteric vein due to systemic diseases such as right - sided heart failure ( 6 - 8 ) .
omental infarction has been reported to occur more frequently on the right side , so clinically it is difficult to differentiate it from either appendicitis or cholecystitis .
the reason may be that the omentum is longer and more mobile on the right side than on the left side ( 9 ) .
however , compared with the usual location and symptoms of the other omental infarctions , omental infarction after odg or ladg with partial omentectomy is located in the mid - line or on the left side of the abdomen and it does not show clinical symptoms at diagnosis in the majority of patients such as our case 1 .
this is because omental infarction is affected by the volume and anatomical location of the remnant omentum rather than the anatomical location of the ligated vessel ( 10 ) .
omental infarction following odg or ladg with partial omentectomy occurs at the remnant greater omentum . the residual area and the abundance of the blood supply for the remnant greater omentum are two important factors that affect the incidence of omental infarction .
the blood supply of the greater omentum travels largely through the right and left gastroepiploic arteries .
usually distal gastrectomy is performed in a patient with early gastric cancer that is localized in the distal stomach and there is very low possibility of omental metastasis .
the left gastroepiploic lns ( 4sb ln ) are classified to the group 3 regional lns for distal third primary gastric cancer according to the jcgc staging system , and the 4sb ln are not included in d2 dissection [ grouping of lns is according to the japanese classification for gastric carcinoma ( jcgc ) staging system by the primary location of cancer . ] for distal third primary gastric cancer ( 3 ) .
so the right gastroepiploic artery is ligated in almost all cases , but on the other hand , the left gastroepiploic artery can be preserved with subtotal gastrectomy .
in addition and anatomically , the greater omentum has a extensive distribution of blood vessels that supply more than the basic metabolic requirements and it sometimes has collateral vessels from the middle colic artery or the superior mesenteric artery . infarction does not usually occur even though most vessels are blocked .
for these reasons , the incidence of secondary omental infarction following distal gastrectomy and partial omentectomy for gastric cancer , either open or laparoscopic assisted , is very low ( 10 ) .
but as laparoscopic surgery is now more commonly performed , the incidence of omental infarction following partial omentectomy with right and left gastroepiploic artery ligation has increased ( 7 , 8) .
the diagnosis of omental infarction is primarily based on the ct findings of an ill - defined heterogeneous mass or interspersed fatty lesion with hyperattenuating streaky infiltration located in the omentum in the early stage , and this progresses to a well - defined , smaller lesion with a hyperdense rim in the late phase ( 9 ) .
these findings can mimic carcinomatosis peritonei in the early phase and peritoneal epiploic appendagitis ( pea ) in the late phase .
clinically , it is important to distinguish omental infarction and carcinomatosis peritonei , and especially for an incidentally detected lesion without any clinical symptoms at follow up ct in gastric cancer patient after distal gastrectomy . in this situation , making the differentiation from carcinomatosis peritonei is as follows : part of the omental infarction shows normal findings on the pet scan , the localized infarcted mass is confined to the remnant omentum , it is progressively smaller in size on the follow up ct without any treatment such as chemotherapy , omental infarction shows different imaging findings depending on the clinical phase , and it appears as ill - defined heterogeneous haziness that mimic carcinomatosis peritonei in the early phase , but it gradually turns into a well - defined fatty mass with a hyper - enhancing peripheral rim that mimics pea , such as in our cases ( 9 ) .
the pathologic diagnosis was not established in our two patients . because the ct scans demonstrated the pathognomonic findings and a natural progressive course of this disease , the diagnosis of omental infarction was not difficult . in many cases , ct is helpful to make a confident diagnosis and so it allow conservative management , and a tissue diagnosis is uncommon .
further reports on pathologic confirmation are needed to evaluate in detail the disease pathophysiology of omental infarction after odg and ladg . in conclusion ,
omental infarction following odg or ladg with partial omentectomy for gastric cancer is very rare , but the incidence is increasing with more widespread use of this procedure .
the ct findings of omental infarction are similar to carcinomatosis peritonei in the early phase . yet
omental infarction following distal gastrectomy with partial omentectomy can be discriminated from carcinomatosis peritonei by the different clinical situation , the different ct findings , the different pet - ct findings and when comparing these findings with the follow up ct .
 omental infarction occurring after open and laparoscopic - assisted distal gastrectomy with partial omentectomy for gastric cancer was a very rare disease in the past , but its incidence has increased as more partial omentectomies are now being performed . 
 but there are few case reports or radiologic studies on its increasing incidence . 
 it is necessary to differentiate omental infarction from carcinomatosis peritonei , since both have similar imaging findings . in this report 
 , we describe two cases of omental infarction ; each occurred after open and laparoscopic - assisted distal gastrectomy in early gastric cancer patients . partial omentectomy was performed in both cases . 
 omental infarction following distal gastrectomy with partial omentectomy can be discriminated from carcinomatosis peritonei by comparing with different initial and follow up ct findings . 
INTRODUCTION
CASE REPORTS
Case 1
Case 2
DISCUSSION