a lymphoepithelioma - like carcinoma ( lelc ) is a tumor which mimics lymphoepithelioma in terms of its pathological features .
the primary lesion of lelc occurs in the stomach , lungs , thymus , salivary glands or urinary bladder .
lelc of the urinary bladder ( lelcb ) is a rare variant of infiltrating urothelial carcinoma and was first described by zukerberg et al . in 1991 .
including this case , there are merely 105 cases in the english language medical literature , with only 8 cases reported as originating from asian countries [ 3 , 4 , 5 , 6 ] . in 1994 , amin et al .  
pure ( 100% ) , predominant ( 5099% ) and focal ( < 50% )  , with the three types determining a patient 's prognosis .
we herein report a case of lelcb , with a preoperative diagnosis of an undifferentiated carcinoma , in which radical cystectomy and systemic chemotherapy were successfully undertaken .
based on previous case reports of lelcb in the english language medical literature , we examined the prognosis for lelcb .
in addition , we analyzed the preoperative diagnostic characteristics of this lelcb by measuring its apparent diffusion coefficient ( adc ) value by magnetic resonance imaging ( mri ) and compared this to those of past cases of urothelial carcinoma of the urinary bladder at our institution .
on cystoscopy , two bladder tumors were observed , one on the left side of the trigone and the other on the right side of the trigone .
a total body computed tomography ( ct ) scan was performed and the presence of distant metastases or lymph node involvement was excluded .
mri revealed that the tumor on the left side of the trigone had invaded the perivesical soft tissue of the bladder , but not the prostate or seminal vesicles ( fig .
pathological findings revealed undifferentiated atypical epithelial cells with enlarged nuclei that had formed into sheets to invade the muscle layer .
pathological findings revealed large , undifferentiated carcinoma cells with pleomorphic nuclei and prominent nucleoli , the infiltration of inflammatory cells consisting predominantly of lymphocytes , and the reach of their invasion to the perivesical soft tissue of the bladder ( fig .
the final pathological diagnosis was an invasive urothelial carcinoma , lymphoepithelioma - like variant , pt3 .
tumor cells were positive for cytokeratin ( ae1/ae3 ) ( fig . 2c ) and e - cadherin ( fig .
, cisplatin - based systemic chemotherapy was performed , and cancer recurrence was not apparent at the usual follow - up as determined by ct scan and cytological analysis .
according to the who classification criteria , lelcb is defined as a subtype of undifferentiated carcinomas .
to date 105 cases , including this one , have been described in the english language medical literature .
lelcb shows carcinomatous components contrasting with lymphocyte infiltration and mimics chronic inflammation or malignant lymphoma ; immunohistochemical stains such as for cytokeratin are helpful in distinguishing between these diseases [ 6 , 7 ] . between 1991 and june 2015 , 84 cases of lelcb , according to the classification of amin et al .
we allocated the 84 cases to two groups  pure / predominant and focal  and investigated their prognoses based on previous reports .
seventy patients ( 83% ) formed the pure / predominant group and 14 patients ( 17% ) formed the focal group .
kaplan - meier curves of overall survival rates of the pure / predominant and focal groups are shown in figure 3 . as a result ,
the pure / predominant group had as significantly better prognosis than the focal type group ( log - rank test , p < 0.001 ) ( fig .
the predominant or focal types of lelcb include squamous cell carcinoma , adenocarcinoma and urothelial carcinoma .
containing only lelc , this case seemed to have the characteristics of a pure type of lelcb .
unfortunately , there is at present no established treatment for lelcb because of its rarity as a bladder tumor subtype , with few reports existing for this disease .
some reports describe lelcb as being sensitive to cisplatin , while others suggest that it is possible to preserve the bladder in the case of a pure or predominant type , even if the tumor has invaded the muscle [ 4 , 8 , 9 , 10 ] .
adjuvant cisplatin - based chemotherapy was also instituted because radical cystectomy yielded a diagnosis of lelcb pt3 .
the combination of external beam radiotherapy and chemotherapy to preserve the bladder may be considered a suitable treatment option if the diagnosis prior to radical cystectomy is accurate .
epstein - barr virus ( ebv ) is associated with lymphoepithelioma or lelc of several tissues ( lung , stomach and salivary glands ) , except the bladder .
a close reading of the literature suggests that if tumor cells are positive for ebv rna , the tumor might be a metastasis from another tissue .
therefore , we performed ebv - encoded small rna in situ hybridization ( eber - ish ) , but this did not reveal a relationship between ebv and lelcb in this case ( fig .
however , in treating lelcb , eber - ish is useful and necessary to rule out the tumor as being a metastasis from another tissue .
mri is widely used in local staging or to detect lymph node metastases , and is essential for determining suitable treatments for bladder tumors . recently ,
measuring adc values has been suggested to be helpful in diagnosing bladder tumors . to further improve preoperative diagnostic accuracy , we retrospectively measured the adc value of this case .
the mean value was found to be 782  10 mm / s ( fig .
1c ) , which was relatively lower than the mean values we found for muscle - invading urothelial carcinomas studied at our institution ( 56 cases , median 1,047  10 mm / s ; see online suppl .
material , www.karger.com/doi/10.1159/000445049 ) . in urothelial carcinoma , in 2014 yamada et al .   reported a correlation between high adc values and good histopathological features of bladder tumors which is the case for urothelial carcinoma .
however , in spite of the relatively low adc value , the prognosis of this case was relatively good as previously described
. the low adc value calculated in this case may be due to the fact that the observed lymphocyte infiltration probably caused an increase in cell density and a decrease in diffusion capacity .
there are several pitfalls and limitations in detecting pathological characteristics of tumors , and further consideration will have to be given to the usefulness of measuring adc values of bladder tumors .
regardless , though lelcb is a rare tumor , measuring adc values may be useful in predicting the histopathological characteristics of such bladder tumors .
we treated a rare case of lelcb , classed as a pure type and with a better prognosis than the focal type according to the classification of amin et al . .
it is necessary to consider a diagnosis of lelcb when turbt indicates an undifferentiated carcinoma .
additionally , measuring the adc value of a urinary bladder tumor may be helpful in predicting its pathological features .
written informed consent was obtained from the patient for publication of this case report and accompanying images .
a copy of the written consent is available for review from the editor - in - chief of this journal .
the authors received no financial support for the research , authorship and/or publication of this paper .
 lymphoepithelioma - like carcinoma of the urinary bladder ( lelcb ) is a rare variant of infiltrating urothelial carcinoma . 
 we report a case of lelcb in a 43-year - old man . 
 ultrasonography and cystoscopy revealed two bladder tumors , one on the left side of the trigone and the other on the right side of the trigone . 
 transurethral resection of the bladder tumors was performed and pathological analysis revealed undifferentiated carcinoma . 
 we therefore performed radical cystectomy and urinary diversion . 
 immunohistochemically the tumor cells were positive for cytokeratin , but negative for epstein - barr virus - encoded small rna in situ hybridization as found for previous cases of lelcb . 
 the final pathological diagnosis was a lymphoepithelioma - like variant of urothelial carcinoma with perivesical soft tissue invasion . 
 for adjuvant systemic chemotherapy , three courses of cisplatin were administered . 
 the patient subsequently became free of cancer 72 months postoperatively . 
 based on the literature , pure or predominant lelcb types show favorable prognoses due to their sensitivity to chemotherapy or radiotherapy . 
 an analysis of the apparent diffusion coefficient ( adc ) values of bladder tumors examined in our institution revealed that the adc value measured for this lelcb was relatively low compared to conventional urothelial carcinomas . 
 this suggests that measuring the adc value of a lymphoepithelioma - like carcinoma prior to operation may be helpful in predicting lelcb . 