primary renal squamous cell carcinoma ( rscc ) is a rare cancer with a variable incidence of about 0.515% of all urothelial cancers [ 14 ] .
there are only isolated case reports and scant case series of such cases in the english literature [ 18 ] .
herein we report four cases of incidentally detected renal pelvis squamous cell carcinomas in patients having a history of staghorn renal calculi with hydronephrosis .
three of the patients were operated for renal stones in our hospital while one was referred to us for confirmation of diagnosis and further management . with the exception of the latter , in whom a suspicious lesion
was seen on imaging studies , in all the rest a carcinoma was unsuspected clinically as well as radiologically , and the diagnosis came to light only on histology . in one case ,
the whole kidney was infiltrated with rscc ; however , there was no suspicion of a tumor on radiology even retrospectively .
our series highlights the need for a renal pelvic biopsy and periodic radiological evaluation in patients undergoing treatment for renal stones , as rscc usually escape detection , with dire consequences for the patient , and are only identified incidentally at late stages , when the patient undergoes surgery for a nonfunctioning kidney .

 case 1a 50-year - old male patient presented with pain in the right flank , off and on for two months .
the blood urea was 43  mg / dl and serum creatinine 1.4  mg / dl .
the total glomerular filtration rate ( gfr ) was 80% with 11.2% on the right side and 89% on the left side .
x - ray of the kidney , ureter and bladder ( kub ) showed presence of bilateral renal calculi with presence of staghorn calculi in the right kidney and multiple small calculi in the left kidney .
the patient underwent a right nephrectomy for right - sided nonfunctioning kidney . on gross examination the kidney
was enlarged and showed a dilated pelvi - calyceal system , presence of calculi in the lumen , and thinning of the renal parenchyma to a narrow peripheral rim .
extensive sampling of the thickened pelvis was done and microscopic examination showed a well - differentiated squamous cell carcinoma ( figure 3(a ) ) , infiltrating the renal parenchyma and surrounding the perirenal fat ( figure 3(g ) ) .
the patient had an uneventful postoperative course but was lost to follow up after discharge from the hospital before his metastatic workup could be performed . 
  a 50-year - old male patient presented with pain in the right flank , off and on for two months .
the blood urea was 43  mg / dl and serum creatinine 1.4  mg / dl .
the total glomerular filtration rate ( gfr ) was 80% with 11.2% on the right side and 89% on the left side .
x - ray of the kidney , ureter and bladder ( kub ) showed presence of bilateral renal calculi with presence of staghorn calculi in the right kidney and multiple small calculi in the left kidney .
the patient underwent a right nephrectomy for right - sided nonfunctioning kidney . on gross examination the kidney
was enlarged and showed a dilated pelvi - calyceal system , presence of calculi in the lumen , and thinning of the renal parenchyma to a narrow peripheral rim .
extensive sampling of the thickened pelvis was done and microscopic examination showed a well - differentiated squamous cell carcinoma ( figure 3(a ) ) , infiltrating the renal parenchyma and surrounding the perirenal fat ( figure 3(g ) ) .
the patient had an uneventful postoperative course but was lost to follow up after discharge from the hospital before his metastatic workup could be performed . 

case 2an 87-year - old man presented with pain in the left lower abdomen since the last two months , increasing since the past few days .
he had a history of percutaneous nephrolithotomy ( pcnl ) for bilateral renal stones 2 years before .
he had a serum urea level of 77  mg / dl and serum creatinine level of 2.8  mg / dl .
grossly the kidney was markedly enlarged with marked dilatation of the pelvicalyceal system and virtually absent residual renal parenchyma ( figure 2(a ) ) .
a single staghorn stone was identified in the dilated calyces . at the upper pole ,
a pale area of thickening was identified measuring 4  2  2  cm .
histological examination of the thickened area in pelvis showed a well - differentiated squamous cell carcinoma infiltrating the perinephric fat .
the patient had coronary complications after surgery and died in the hospital . 
  an 87-year - old man presented with pain in the left lower abdomen since the last two months , increasing since the past few days .
he had a history of percutaneous nephrolithotomy ( pcnl ) for bilateral renal stones 2 years before .
he had a serum urea level of 77  mg / dl and serum creatinine level of 2.8  mg / dl .
grossly the kidney was markedly enlarged with marked dilatation of the pelvicalyceal system and virtually absent residual renal parenchyma ( figure 2(a ) ) .
a single staghorn stone was identified in the dilated calyces . at the upper pole ,
a pale area of thickening was identified measuring 4  2  2  cm .
histological examination of the thickened area in pelvis showed a well - differentiated squamous cell carcinoma infiltrating the perinephric fat .
two lymph nodes identified at the renal hilum showed metastasis . with these features , the stage was  stage iv ( pt3pn2cm0 ) .
case 3a 50-year - old female patient presented with complaints of pain in the left flank three months ago .
there was reduced urine output ( 600700  ml / day ) ; however , there was no hematuria .
x - ray of kub showed radiopaque shadows in the left kidney and pelvis ( figure 1(a ) ) .
intravenous pyelography ( ivp ) revealed non functioning left kidney ( figure 1(b ) ) .
the patient underwent   left nephrectomy , and on gross examination , the kidney was normal sized ; however , showed few dilated calyces with lodged stones .
surprisingly , nearly the whole kidney was replaced by a solid grey - white tumor , surrounding the dilated calyces , with a scant rim of renal parenchyma seen at the periphery ( figure 2(b ) ) .
microscopy of the tumor revealed a poorly differentiated squamous cell carcinoma ( figures 3(b ) and 3(e ) ) .
the metastatic work - up was negative , and hence she was staged as stage ii ( pt2n0m0 ) .
currently three months after surgery , the patient is alive and undergoing cisplatin - based chemotherapy . 
  a 50-year - old female patient presented with complaints of pain in the left flank three months ago .
there was reduced urine output ( 600700  ml / day ) ; however , there was no hematuria .
x - ray of kub showed radiopaque shadows in the left kidney and pelvis ( figure 1(a ) ) .
intravenous pyelography ( ivp ) revealed non functioning left kidney ( figure 1(b ) ) .
the patient underwent   left nephrectomy , and on gross examination , the kidney was normal sized ; however , showed few dilated calyces with lodged stones .
surprisingly , nearly the whole kidney was replaced by a solid grey - white tumor , surrounding the dilated calyces , with a scant rim of renal parenchyma seen at the periphery ( figure 2(b ) ) .
microscopy of the tumor revealed a poorly differentiated squamous cell carcinoma ( figures 3(b ) and 3(e ) ) .
the metastatic work - up was negative , and hence she was staged as stage ii ( pt2n0m0 ) .
currently three months after surgery , the patient is alive and undergoing cisplatin - based chemotherapy . 

case 4a 53-year - old male presented with complaints of bilateral flank pain since the last five months .
he was previously operated twice for renal stones , having a right pyelolithotomy 16 years before and a right pcnl seven years before .
diethylene triamine pentaacetic acid ( dtpa ) scan showed a small very poorly functioning kidney on the right side .
total gfr was 68.88  ml / min with gfr of the right kidney being 8.09  ml / min and of left being 60.8  ml / min .
contrast enhanced computerized tomography ( cect ) scan showed small irregular hydronephrotic right kidney with a suspicious nodular lesion ( figures 1(c ) and 1(d ) ) .
the left kidney also showed lower calyceal and lower ureteric calculi but with normal renal function .
grossly the kidney was small and showed a dilated pelvicalyceal system filled with pus and fragments of renal calculi .
a solid grey - white nodular lesion with areas of necrosis , measuring 2  1.2  cm , was present near the lower pole .
histopathology of the lesion showed a moderately differentiated squamous cell carcinoma , with solid and focal papillary pattern ( figures 3(c ) and 3(d ) ) .
the patient was referred to our hospital for confirmation of the diagnosis and further management .
he is alive five months after surgery and undergoing cisplatin - based chemotherapy . 
  a 53-year - old male presented with complaints of bilateral flank pain since the last five months .
he was previously operated twice for renal stones , having a right pyelolithotomy 16 years before and a right pcnl seven years before .
diethylene triamine pentaacetic acid ( dtpa ) scan showed a small very poorly functioning kidney on the right side .
total gfr was 68.88  ml / min with gfr of the right kidney being 8.09  ml / min and of left being 60.8  ml / min .
contrast enhanced computerized tomography ( cect ) scan showed small irregular hydronephrotic right kidney with a suspicious nodular lesion ( figures 1(c ) and 1(d ) ) .
the left kidney also showed lower calyceal and lower ureteric calculi but with normal renal function .
grossly the kidney was small and showed a dilated pelvicalyceal system filled with pus and fragments of renal calculi .
a solid grey - white nodular lesion with areas of necrosis , measuring 2  1.2  cm , was present near the lower pole .
histopathology of the lesion showed a moderately differentiated squamous cell carcinoma , with solid and focal papillary pattern ( figures 3(c ) and 3(d ) ) .
the patient was referred to our hospital for confirmation of the diagnosis and further management .
cancers of the kidney and renal pelvis are the ninth most common malignant cancer and form the 12th most common cause of all cancer - related deaths . of all urothelial tumors ,
only 5 - 6% occur in the upper urinary tract ( renal pelvis and ureter ) , and of these only about 615% are squamous cell carcinomas . among malignant renal tumors ,
scc are decidedly rare neoplasms and form only about 0.58% [ 13 , 9 , 10 ] .
over one year ( 1st january 2010 to 31st december 2010 ) , 15 patients with hydronephrosis and nonfunctioning kidney were operated at our hospital and one case of such an operation was sent to us for review . of these 16 cases ,
on reviewing all malignant renal tumors diagnosed in our department during the same time period , we found that rscc comprised 4/21 cases ( 19% ) .
the remaining cases comprised 11 cases of clear cell adenocarcinoma ( 52% ) , two cases of papillary adenocarcinoma ( 9.5% ) , and one case each of chromophobe renal cell carcinoma , one case of collecting duct carcinoma , one case of wilm 's tumor , and one case of transitional cell carcinoma ( 4.8% each ) .
the relatively high incidence of rscc in our series could be due to the referral pattern of our hospital , which is a tertiary care referral institute .  
table 1 shows the various clinical features and pathological findings of the cases in the present series .  
most of the current data of rscc is derived from small case series , over time periods ranging from 6 years to 27 years , and few isolated case reports [ 18 ] .
the predisposing factors leading to development of rscc are chronic irritation due to preexisting renal stones ( most commonly of the staghorn type ) or prior surgery for renal stones , analgesic abuse , or radiotherapy .
chronic irritation induced by the aforementioned conditions , superimposed by infection , is believed to induce squamous metaplasia and subsequent development of leukoplakia and neoplasia in the urothelium , resulting in rscc [ 18 , 11 ] .  
clinically , the mean age of presentation is 56 years , and contrary to earlier reports , there is equal incidence in males and females .
the involvement is unilateral , equally common on the right and left sides . presenting symptoms include loin pain , hematuria , and abdominal lump [ 1 , 2 , 4 ]
. history of previous surgery for renal stone or staghorn calculi in patients of rscc has been reported variably from only 12.3% of cases in one series to 100% of cases in others [ 2 , 4 ] .
li and cheung   reported an incidence of rscc in 2% of patients with recurrent renal stones . in the present series ,
the mean age was 60 years , m  :  f ratio was 3  :  1 , right side to - left - side ratio was 1  :  1 , and most common presenting symptom was flank pain .
hematuria was observed in only one of our patients and may have been due to renal stones .
this is similar to the study by li and cheung . in all of our cases ( 100% )
there was presence of staghorn type of renal stones . in two of our four cases ( 50% )
there was history of prior surgery for renal stones and three out of four patients ( 75% ) had a history of bilateral renal calculi .  
significantly , due to nonspecific and insidious presenting symptoms such as flank pain and hematuria , which often overlap with symptoms of renal stones , lack of specific radiological features , and rarity of this tumor , most cases of rscc are undiagnosed preoperatively and come to light only on histopathological examination of the excised non functioning kidney [ 2 , 3 , 5 , 6 , 8 , 12 ] .
a retrospective review of radiological findings in rscc showed that conventional radiological findings of filling defects , obstructive lesions or nonfunctioning kidney by intravenous urography ( ivu ) , which have been documented sporadically in   the literature , are all nonspecific .
because of this , a renal tumor usually remains unsuspected and further radiological evaluation such as computerised tomography ( ct ) is not done routinely in every case , especially in developing countries , where the cost of these investigations is an issue .
even ct imaging does not help in exact diagnosis , but may provide helpful information regarding the anatomical extent of the tumor .
found that the most helpful features in ct of rscc were presence of enhancing extraluminal and exophytic mass and , in some cases , an intraluminal component .
they further suggested , that as it is impractical to perform ct for every patient with renal stone , ivu should be done periodically , especially in long standing stones , and should be read as a split function test for all portions of renal parenchyma . in such cases , filling defects , delay in appearance of pyelogram , or renal parenchymal thickening should be regarded as renal tumor despite the   absence of mass effects and preservation of renal contour , warranting further studies by ct or biopsy from renal pelvis or calyces during treatment for renal stones . in the present series , similar to the literature ,
due to nonspecific clinical and radiological features , there was lack of confirmed preoperative diagnosis of a renal tumor in all our cases . in 3 of our 4 cases ,
ct was not done preoperatively as clinically , and on conventional radiology such as x - ray , ultrasonography , and ivu , the diagnosis was non functioning kidney with staghorn calculi and hydronephrosis . in 2 of these 3 cases ( cases 1 and 2 ) ,
gross inspection showed only focal areas of thickening of pelvis which were extensively sampled and microscopic examination proved them to be rscc . in the third case , even though the diagnosis was evident on gross examination of the resected specimen , as almost the whole kidney was replaced by the tumor , even a retrospective radiological review did not show any evidence of a tumor , much to the surprise of our radiologists . in the fourth case , though no tumor was suspected clinically , a ct scan was performed and revealed a suspicious nodule present intraluminally in the region of the pelvis and histological examination advised .
hence our series underlines the fact that rscc may be missed , clinically as well as radiologically , in a high number of cases , and the diagnosis may only be incidental during microscopic examination , provided extensive sampling of the kidney , particularly of the renal pelvis , has been done , specially if there is any area of thickening .
due to the above - mentioned reasons , most patients of rscc present at late stages , accounting for the poor prognosis [ 1 , 2 , 4 , 5 , 12 ] .
compared rscc with urothelial carcinomas ( ucs ) and found that though there was no significant difference in prognosis in advanced stage ( pt3 and pt4 ) rscc and uc , more patients of rscc presented at advanced stage ( 94% ) than uc ( 37% ) .
hence , the outcome of rscc patients is poor with median survival of only 57 months after surgery and less than 10% alive after 5 years [ 1 , 2 , 4 , 5 ] . in the present series ,
similarly three of our four patients ( 75% ) presented at advanced stage ( pt3 and pt4 ) . in one of the patients with stage pt3 ,
the nodal status was also advanced ( pn2 ) , upstaging the patient to stage iv .
only case 3 , the 50-year - old female , had a lower stage ( pt2 ) .  
histologically , nearly a fourth of rscc also shows other histological patterns focally including micropapillary , lymphoepithelial , small cell , and sarcomatoid .
rscc with solid and papillary pattern has been seen in 14% of cases in one large series , and most cases are high grade . in our series , one of the four cases ( 25% ) showed a mixed solid and papillary pattern .
two cases were of well - differentiated scc ( 50% ) ,   one of   moderate ( 25% ) and   one of poorly differentiated scc ( 25% ) .
radical nephroureterectomy with excision of bladder cuff is the treatment of choice in patients without metastasis ; however , in view of the unifocal nature of this disease , parenchyma sparing surgeries have also been proposed [ 2 , 4 , 5 , 8 , 12 ] .
cisplatinum - based adjuvant chemotherapy and radiotherapy are usually given due to the advanced stage and poor prognosis in most patients but have shown no survival benefit , highlighting the need for early diagnosis [ 1 , 2 , 4 , 8 , 10 ] .
one of our patients was lost to follow up , one died of intercurrent cad while the remaining two ( one pt2 and the other pt3 ) were on cisplatinum - based chemotherapy and surviving three and five months after surgery , respectively .
primary rsccs are rare tumors and show a strong association with renal stones , which might confound diagnosis
. they may not be radiologically detectable and the first indication of malignancy might come incidentally on histological examination of nephrectomy for nonfunctioning hydronephrotic calculous kidney .
this emphasises the necessity of prompt treatment of renal stones and assessment for renal tumors in patients with long - standing staghorn calculi .
the high incidence of rscc in hydronephrotic kidneys in our series also highlights the need for meticulous sampling of the renal pelvis by the pathologist in such specimens .
 squamous cell carcinoma of the renal pelvis is a rare neoplasm , often unsuspected clinically due to its rarity and ambiguous clinical and radiological features , and hence patients present at advanced stages resulting in poor prognosis . 
 we report here four cases of incidentally diagnosed primary renal squamous cell carcinoma , treated at our hospital over a short span of one year , and review the relevant literature . 
 mean age of the patients ( 3 males , 1 female ) was 60 years . 
 all suffered from staghorn stones . 
 interestingly , renal carcinoma was unsuspected clinically in all patients . in one case , a computerised tomography scan showed a suspicious nodule . 
 all underwent nephrectomy for nonfunctioning kidney . in just two cases , 
 tumor was identified on gross examination , while the other two only showed thickened pelvis . 
 our series emphasises the need for pelvicalyceal biopsy during treatment for long - standing nephrolithiasis , and thorough sampling of the renal pelvis in nephrectomy specimen of such patients . 
1. Introduction
2. Case Series
3. Discussion
4. Conclusion