solitary fibrous tumors ( sfts ) are rare mesenchymal neoplasms of fibroblastic origin , most commonly found in the pleura .
in fact , they are ubiquitous neoplasms , and non - serosal extrathoracic locations have been reported during the last 2 decades , including intra - abdominal cases .
given the rarity of these tumors , misdiagnosis is frequent , and information regarding prognosis and treatment is lacking .
herein , we report the first case of sft developing in the round ligament of the liver .
in august 2010 , a 46-year - old caucasian man presented with a 12-month history of abdominal pain . he had no specific medical history , personal or familial . the initial ultrasonography ( us )
scan , performed 1 year earlier , was interpreted as normal . on self - examination
a ct scan showed a solid and inhomogeneous mass measuring 182  66 mm , located under the abdominal wall , causing displacement of the left and right hepatic lobes but distinct from them ( fig .
iodine injection showed heterogeneous contrast uptake , with a fat interface between the tumor and intra- and retroperitoneal elements ( fig .
histological examination showed a proliferation of nonatypical round to spindle - shaped cells without mitoses , admixed with collagen .
immunohistochemistry ( ihc ) showed no expression of epithelial , smooth muscle or schwann cell markers by tumor cells but solely expressed cd34 .
a diagnosis of gastrointestinal stromal tumor ( gist ) was ruled out by ihc ( no expression of cd117 or dog1 ) and molecular biology ( no kit or pdgfra mutation ) , and the diagnosis of desmoid tumor was made .
second - line treatment based on imatinib ( 400 mg daily ) was started . despite 3 months of treatment ,
the initial biopsy was reexamined and regarded as suspicious for low - grade sarcoma or sft .
mri was performed : on t2-weighted sequences , the tumor had a higher signal than the muscle ( fig .
2a ) ; gadolinium injection was associated with gradual and heterogeneous contrast enhancement on t1-weighted sequences , evoking fibrosis ( fig .
2b ) , but diffusion mri showed important cellularity that was highly suspicious for a malignant process ( fig . 2c ) .
laparotomy found a huge and well - limited tumor that , unexpectedly , was appended to the round ligament of the liver ( fig .
the tumor was free from any other intra - abdominal contact , especially from the liver parenchyma , and was easily removed without any further dissection .
the tumor measured 210  70 mm and weighed 1,990 g. after formalin fixation , it showed a fleshy appearance with gray - white color on cut section and was centered on and appended to the round ligament ( fig .
unlike the microbiopsy , the histological examination of the surgical specimen showed many more characteristic areas of small nonatypical spindle cells scattered in a fibrous stroma without any clear architecture ( fig .
3e ) . ihc analysis confirmed strong expression of cd34 by tumor cells and , above all , highlighted very characteristic ramified vessels , so - called 
3f ) . there was no expression of epithelial ( pancytokeratin , ema ) , smooth muscle ( -smooth actin ) , and schwann cell ( ps100 ) markers .
mitotic count was very low , less than 1 mitosis per 10 high - power fields ( hpf ) .
a regular clinical and radiological monitoring was set up . at the 10-month follow - up ,
the patient was alive with excellent ps , without any signs or symptoms of relapse .
in the past 2 decades , sfts have been identified in the abdominopelvic cavity [ 2 , 3 ] . regarding the liver , fewer than 30 cases
have been reported in the english literature [ 4 , 5 , 6 ] . to our knowledge
, our case represents the first case of sft arising from the round ligament of the liver .
the round ligament , or ligamentum teres , is a degenerative string of tissue stemming from the umbilical vein involution and that anatomically divides the left lobe of the liver from the medial and lateral sections .
most of them are metastases of gastrointestinal cancers ( in particular , mucinous appendiceal neoplasm ) , peritoneal mesothelioma , and more rarely of breast cancer and hepatocarcinoma [ 8 , 9 ] . cases of primary mesenchymal tumors have also been reported , including sarcomas ( malignant fibrous histiocytoma , leiomyosarcoma ) , and benign tumors such as lipomas , lymphangiomas , stromal tumors   and pecomas .
sfts of the round ligament of the liver have not been reported so far . given
they often manifest as large , asymptomatic , slow - growing tumors , and their clinical presentation has no specificity ( pain , abdominal mass ) . in our case , it is likely that the tumor had been evolving slowly for several years before the onset of abdominal pain , and that the us scan was falsely negative because of similar echogenicity between the tumor and the perihepatic tissues .
these tumors demonstrate remarkable radiological heterogeneity , with variable degrees of enhancement , necrosis , or hemorrhage .
ct is the initial investigative modality of choice for the detection of sfts , and is better than a us scan , as exemplified in our case .
typically , the tumor appears as a well - circumscribed hypervascular mass that may displace or exert pressure effects on neighboring organs . at mri
, it typically displays intermediate signal intensity on t1-weighted images , heterogeneous low - signal intensity with flow voids on t2-weighted images , and intense enhancement after administration of gadolinium . in our case , these features existed , but diffusion mri was falsely alarming . on presurgical imaging ,
the large size of the tumor did not allow for the definition of its precise origin or the prediction of a simple surgical removal .
the origin in the round ligament was obvious during the laparotomy only ; however , a postoperative re - reading of the initial ct and mri scans showed that the tumor had infiltrated the umbilical fissure .
the positive diagnosis of sfts is histological , while keeping in mind the frequent difficulty to precisely characterize a mesenchymal neoplasm on small biopsies , as illustrated by our case .
analysis shows a proliferation of rounded to fusiform cells arranged without any well - defined architecture ( so - called 
appearance can be very different from one area to another depending on the relative proportion of cells and stroma .
ihc shows strong expression of cd34 by tumor cells and importantly helps to rule out numerous differential diagnoses , namely smooth muscle tumors , desmoid tumors , tumors of peripheral nerves , gist , spindle cell sarcomas , notably dedifferentiated liposarcomas and synovial sarcomas .
as with our patient 's tumor , molecular biology can also help to rule out some differential diagnoses , mainly gists .
regarding their prognosis , extrapleural sfts have a classically more indolent behavior than pleural sfts and are most always defined as benign
. however , their clinical outcome is unpredictable , and some of them can display histological aggressiveness criteria ( size > 5 cm , mitotic count > 4 per 10 hpf , high cellularity , necrosis , hemorrhage , cytological atypia and infiltrative growth pattern ) or present local invasiveness or local or metastatic relapses [ 3 , 13 ] . like in pleural locations ,
the presence of aggressive features does not always forecast an unfavorable clinical outcome , and half of cases with a malignant lesion ( defined by the presence of high cellularity and/or high mitotic count and/or pleomorphism ) are cured by simple excision . for many authors ,
the complete resection of the tumor is the most important prognostic factor . in our case , and thanks to its  fortunate origin in the round ligament , the tumor was easily and completely removed , and the only pejorative criterion was its large size .
surgical excision is the treatment of choice for sfts , with a 5-year survival rate close to 100% after complete excision .
systemic chemotherapy and radiotherapy have been tried , but with variable success rates . in unresectable sfts ,
antiangiogenic therapy is associated with promising results . as the evolution of extrapleural sfts is unpredictable
this is the first report of sft arising from the round ligament of the liver described in the literature .
even though rare , this diagnosis should be kept in mind to allow early diagnosis and complete surgical resection , which provide the best chance for recovery .
 solitary fibrous tumors ( sfts ) are mesenchymal neoplasms of fibroblastic origin , most commonly found in the pleura . 
 numerous extrathoracic locations have been reported during the last 2 decades . 
 herein , we report the first case of an sft in the round ligament of the liver . a 46-year - old caucasian man presented with a 12-month history of abdominal pain . 
 an ultrasonography - guided microbiopsy first revealed a desmoid tumor . 
 after failure of first- and second - line medical treatments ( celecoxib and tamoxifen , then imatinib ) , histological reexamination was suspicious for a low - grade sarcoma . 
 mri was also suspicious for a malignant process . 
 hence , surgery was decided . 
 laparotomy found a huge and well - limited tumor that , unexpectedly , was appended to the round ligament of the liver and free from any other intra - abdominal contact . 
 the tumor was easily removed . 
 excision was monobloc and macroscopically complete . 
 histological analysis diagnosed an sft arising from the round ligament of the liver . 
 no adjuvant treatment was given . 
 ten months after surgery , the patient is alive without any signs or symptoms of relapse . 
 this is the first report of sft arising from the round ligament of the liver . 
 it illustrates the difficulty in diagnosing such tumors . whilst diagnosis of sft is rare , 
 it should be kept in mind to allow early diagnosis and complete surgical resection , which provide the best chance for recovery . 
Introduction
Case Report
Discussion
Conclusion
Disclosure Statement