approximately 24% of non - hodgkin 's lymphomas are considered to be of extranodal origin .
primary uterine non - hodgkin 's lymphomas are extremely rare accounting for < 1% of all extranodal non - hodgkin 's lymphomas .
however , the diagnosis of primary uterine lymphoma is often delayed due to its low incidence and nonspecific clinical presentation .
, we present magnetic resonance imaging ( mri ) and fluorine-18-fluorodeoxyglucose ( f - fdg ) positron emission tomography ( pet)/ct findings in a patient with primary uterine peripheral t - cell lymphoma .
a 27-year - old female was admitted to our hospital because of intermittent fever with neutropenia for 7 months .
laboratory tests showed decreased white blood cell count ( 1.4    10/l ; range 410    10/l ) .
serum cancer antigen 125 was elevated ( 193  u / ml ; range < 35  u / ml ) .
mri showed an ill - defined mass involved both the uterine corpus and cervix , resulting in diffuse enlargement of the uterus .
this mass showed inhomogeneous hypointensity on unenhanced t1-weighted images , hyperintensity on diffusion - weighted imaging , relative hypointensity compared to the surrounding myometrium on t2-weighted images , and lower enhancement than the surrounding myometrium on enhanced t1-weighted images ( figure 1 ) .
, f - fdg pet / ct was performed showing intense fdg uptake in the thickened wall of the uterine corpus and cervix with suvmax of 26.9 .
there were multiple hypermetabolic lymph nodes in the pelvis and retroperitoneum ( figure 2 ) .
transverse unenhanced t1-weighted image ( a ) showed an inhomogeneous hypointense mass ( arrows ) in the uterus . corresponding transverse diffusion - weighted imaging ( b ) showed peripheral hypointensity of the mass .
saggital t2-weighted mr image ( c ) showed the mass ( arrows ) involved both the endomerium and myometrium , resulting in diffuse enlargement of the uterus .
this mass showed relative hypointensity compared to the surrounding myometrium . on transverse ( d ) , coronal ( e ) , and saggital ( f ) enhanced t1-weighted images , this mass showed lower enhancement ( arrows ) than the surrounding myometrium .
maximum intensity projection pet ( a ) showed intense fdg uptake of the enlarged uterus ( arrow ) and multiple hypermetabolic lymph nodes ( arrowheads ) in the pelvis and retroperitoneum .
transverse ct ( b , c ) , corresponding pet ( d , e ) , and fused ( f , g ) images showed intense fdg uptake in the thickened wall of the uterine corpus ( arrows ) and cervix ( arrowhead ) with suvmax of 26.9 .
ct  =  computed tomography , fdg  =  fluorodeoxyglucose , mri  =  magnetic resonance imaging , pet  =  positron emission tomography .
microphotograph revealed diffuse myometrial infiltration by small round tumor cells with multifocal coagulative necrosis ( figure 3a ) .
the tumor cells were positive for cd2 , cd3 ( figure 3b ) , cd43 , and lat , and negative for cd19 and cd20 .
the imaging and pathologic findings were consistent with primary peripheral t - cell lymphoma of the uterus ( stage , ii e ) . after 3 circles of chemotherapy , a follow - up mri showed decreased thickness of the uterine wall ( figure 4 ) .
histopathology at higher magnification ( a , hematoxylin - eosin , original magnification    400 ) revealed diffuse myometrial infiltration by small round tumor cells .
the tumor cells were positive for cd3 staining ( b , original magnification    400 ) .
a follow - up enhanced t1-weighted image showed decreased thickness of the uterine wall after 3 circles of chemotherapy .
primary uterine non - hodgkin 's lymphomas are extremely rare accounting for < 1% of all extranodal non - hodgkin 's lymphomas .
the mean age of patients with primary uterine non - hodgkin 's lymphoma at presentation is 55 years and abnormal uterine bleeding is the most frequent complaint .
the combination of chemotherapy and irradiation is the most effective treatment regimen for uterine lymphomas . on mri , diffuse enlargement of the uterus , relatively homogeneous signal intensity , and multinodular growth pattern
are helpful for diagnosing uterine lymphoma . in this case , on t2-weighted mr images , the tumor showed relative hypointensity compared to the surrounding myometrium , which may be due to the hypercellularity and less necrosis of the tumor . on diffusion - weighted imaging ,
the tumor showed remarkable hyperintensity indicating marked restricted diffusion of the water molecules due to the dense microstructure . on enhanced t1-weighted mr images , the tumor showed lower enhancement than the surrounding myometrium , which may be due to the minimal tumor angiogenesis and destroying of the normal uterine vessels .
mri may be helpful for the differential diagnosis between uterine lymphoma and uterine leiomyosarcoma or abscess . unlike uterine lymphoma , hemorrhage and necrosis are common in uterine leiomyosarcoma .
therefore , uterine leiomyosarcoma commonly manifests as a large infiltrating myometrial mass with heterogeneous hypointensity on t1-weighted mr images , and intermediate - to - high signal intensity with central hyperintensity on t2-weighted mr images .
uterine abscesses commonly show high - signal intensity on t2-weighted mr images , which is different from relative hypointensity of uterine lymphoma .
fdg pet / ct may be useful for detection , staging , and treatment evaluation of uterine lymphoma .
high - grade uterine lymphomas usually show intense fdg uptake , whereas the low - grade ones show lower fdg uptake . therefore , fdg pet / ct may be helpful for assessment of the tumor grade .
this case indicates uterine lymphoma should be included in the differential diagnosis of abnormal uterine fdg accumulation along with physiological endometrial uptake , postpartum uterus , adenomyosis , endometrial hyperplasia , leiomyoma , cervical cancer , endometrial cancer , choriocarcinoma , uterine sarcoma , and uterine metastasis . in conclusion , primary uterine non - hodgkin 's lymphoma should be taken into consideration when a uterine tumor shows large size , relative hypointensity on both t2-weighted images and enhanced t1-weighted images compared to the surrounding myometrium , and intense fdg uptake on pet / ct .
ethical approval was obtained from the ethics committee of changhai hospital , shanghai , china .
written informed consent was obtained from the patient for publication of this case report and any accompanying images .
 abstractprimary uterine non - hodgkin 's lymphoma is extremely rare accounting for < 1% of all extranodal non - hodgkin 's lymphomas . 
 imaging findings of primary uterine lymphoma have rarely been reported before . 
 we present magnetic resonance imaging ( mri ) and fluorine-18-fluorodeoxyglucose ( 18f - fdg ) positron emission tomography ( pet)/ct findings in a patient with primary uterine peripheral t - cell lymphoma.a 27-year - old female presented with intermittent fever with neutropenia for 7 months . 
 mri showed an ill - defined mass involved both the uterine corpus and cervix , resulting in diffuse enlargement of the uterus . 
 this mass showed inhomogeneous hypointensity on unenhanced t1-weighted images , hyperintensity on diffusion - weighted imaging , relative hypointensity compared to the surrounding myometrium on t2-weighted images and lower enhancement than the surrounding myometrium on enhanced t1-weighted images . 
 fdg pet / ct showed intense fdg uptake in the thickened wall of the uterine corpus and cervix with suvmax of 26.9 . 
 there were multiple hypermetabolic lymph nodes in the pelvis and retroperitoneum . 
 uterine curettage and ct - guided biopsy of the uterine mass revealed peripheral t - cell lymphoma . 
 bone marrow biopsy revealed no evidence of lymphomatous involvement . 
 the imaging and pathologic findings were consistent with primary uterine lymphoma . 
 after 3 circles of chemotherapy , follow - up enhanced mri showed decreased thickness of the uterine wall.despite its rarity , primary uterine non - hodgkin 's lymphoma should be taken into consideration when a uterine tumor shows large size , relative hypointesity on both t2-weighted images and enhanced t1-weighted images compared to the surrounding myometrium , and intense fdg uptake on pet / ct . 
 mri may be helpful for describing the relationship between the tumor and adjacent structures . 
 fdg pet / ct may be useful for tumor detection and staging . 