liposarcomas are histologically divided into five subtypes : myxoid , pleomorphic , dedifferentiated , round cell , and well - differentiated ( wd ) liposarcoma ( atypical lipomatous tumor ) .
approximately 75% develop in the deep soft tissue of the limbs , followed by 20% in the retroperitoneum and a much smaller percentage in the inguinal region .
other sites are uncommon ; in particular , primary wd liposarcoma in the mesentery is rare .
. here , a case of wd liposarcoma in the duodenal mesentery is presented , and the literature is reviewed .
the patient was a 73-year - old japanese man who received follow - up care for viral hepatitis , liver cirrhosis , and hepatocellular carcinoma by a gastroenterologist at the takii hospital of the kansai medical university .
he had noticed the presence of an upper abdominal mass for approximately 1 year , but did not seek treatment due to the lack of symptoms . finally , he consulted a gastrointestinal surgeon because of the rapid growth of the abdominal mass and upper abdominal insufficiency .
physical examination revealed a large and movable mass palpated in the left upper abdomen , and computed tomography showed a well - circumscribed tumor mass with no metastases .
tumor markers , including carcinoembryonic antigen , ca19 - 9 , and -fetoprotein , were within normal limits .
the upper abdominal tumor was located in the duodenal mesentery close to the ligament of treitz with no adhesion to the surrounding organs , such as the transverse colon and liver .
the patient remained healthy without any evidence of recurrence for 6 months after the surgery .
the excised tumor was a well - circumscribed mass that was 12.4  9.6 cm in size and weighed 548 g. cut sections of the tumor showed a lobulated yellow and/or grayish - colored appearance with no necrotic areas ( fig .
different histologic areas were separated by broad fibrous septa containing cells with enlarged hyperchromatic and atypical nuclei ( fig .
some areas contained collagen fibrils of varying density embedded with spindle cells , including multinucleated giant cells and some cells exhibiting a floret - like pattern ( fig . 2b ) .
other areas consisted predominantly of mature fat cells that were variable in size ; the nuclei of these cells were slightly pleomorphic and hyperchromatic ( fig . 2c ) .
additionally , there were areas of dense lymphocytic infiltration and/or myxoid change . within the tumor ,
the labeled streptavidin biotin ( lsab ) technique was performed with an lsab staining kit ( dako , carpinteria , denmark ) and the antibodies listed in table 1 .
3a ) , and a few cells were positive for -smooth muscle actin but negative for desmin .
fat cells were s-100 positive , whereas spindle cells were s-100 negative . in tumor cells ( including both spindle cells and fat cells ) , the average ki-67 proliferation index was 10% ( fig .
the tumor was determined to be a wd liposarcoma ( atypical lipomatous tumor ) that primary originated from the duodenal mesentery .
we report a case of primary wd liposarcoma originating in the mesentery of a 73-year - old man .
the most common differential diagnostic problem of wd liposarcoma is its distinction from spindle cell / pleomorphic lipoma .
lipoma - like wd liposarcomas can be identified by the population of various - sized fat cells , including atypical nuclei and immature fat cells .
a characteristic feature of spindle cell / pleomorphic lipomas is the presence of floret - type giant cells .
however , floret - type giant cells are rarely seen in wd liposarcomas , and then only in small numbers . in the present case , floret - like multinucleated cells were observed in sclerotic regions . similar to myxoid liposarcomas , wd liposarcomas occasionally may have a predominantly myxoid appearance .
however , it is not definite that widespread cd34 immunoreactivity can exclude other lipomatous neoplasms ; diffuse cd34 staining in a lipomatous tumor may simply reflect the presence of spindle cells [ 6 , 7 ] . in the present case ,
cd34 showed diffuse and strong positivity in spindle - shaped and multinucleated giant cells embedded in the sclerotic stroma .
immunohistochemical detection of cdk4 and mdm2 as well as gene amplification of cdk4 and mdm2 status has been shown to be a sensitive and specific means of identifying wd liposarcoma from other benign lipomatous tumors . in our study , some tumor cell nuclei were cdk4 positive , and a smaller number of cell nuclei were mdm2 positive . moreover , in agreement with a previous report , the ki-67 index was highly suggestive of wd liposarcoma in the present case . the cytogenetic pattern of wd liposarcoma is characterized by the consistent presence of circular ( ring ) and giant rod chromosomes [ 1 , 5 ] .
however , in the present case , fresh material was not available for a cytogenetic study .
primary wd mesenteric liposarcomas are rare with only 12 well - documented cases ( including the present case ) in the english literature ( table 2 ) [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]
. wd mesenteric liposarcoma tends to occur in the fourth to seventh decades of life ( mean age 57.9 years ) with no difference in frequency based on the patients sex ( men / women : 7/5 ) .
although immunoreactivity for androgen receptor has not been systematically studied in wd liposarcomas , the expression of androgen receptor was seen in the tumor cells in the present case .
endogenous and/or exogenous steroids via the androgen receptor may be involved in the growth of this tumor .
wd liposarcomas are relatively large in size , and most tumors are over 10 cm in diameter at the time of surgery .
wd liposarcomas can be subdivided into the following groups : lipoma - like , sclerosing , inflammatory , and spindle cell .
the presence of more than one histologic variant is common in single tumors , and subclassification does not indicate any prognostic significance . in our survey , we found that mixed variants are frequently described in wd liposarcomas . among the 12 cases , local recurrence occurred in 2 cases
. surgical margin may be the most important prognostic factor in that incomplete resection may lead to recurrence , and the risk of dedifferentiation may also be considered . in conclusion , complete resection and long - term follow - up are necessary for wd mesenteric liposarcoma due to the risk of local recurrence of the tumor .
 mesenteric liposarcoma is a rare neoplasm . here , we report the case of a 73-year - old japanese man with a well - differentiated ( wd ) liposarcoma of the mesentery . due to rapid growth of the abdominal mass and abdominal insufficiency , 
 a tumorectomy was performed . 
 the excised tumor was 12.4  9.6 cm in size and weighed 548 g. cut sections showed a lobulated yellow and/or grayish - colored appearance . 
 the histological features were predominantly those of the sclerotic and lipoma - like variants of wd liposarcoma . 
 the cytoplasm of most spindle cells was diffusely immunoreactive for cd34 , while fat cells were positive for s-100 protein . 
 some spindle cell nuclei were positive for cdk4 , and a few were positive for mdm2 . 
 the average ki-67 proliferation index in tumor cells was 10% , and androgen receptor expression was detected in tumor cell nuclei . 
 the present case and 11 cases identified from a literature search were reviewed . 
 the wd mesenteric liposarcomas developed in patients in the fourth to seventh decades of life ( mean age 57.9 years ) . 
 the patients consisted of 7 men and 5 women . 
 all tumors were larger than 10 cm in diameter at the time of surgery . 
 complete resection might be the only curative therapy for wd liposarcomas of the mesentery , but long - term follow - up is needed because of the possibility of a local recurrence of the tumor . 
Introduction
Case Report
Discussion
Disclosure Statement