sarcoidosis is a multisystem disease of undetermined cause which is characterized by the widespread presence of non - caseating granuloma .
autopsy - based series report prevalence rates of renal involvement between 7 and 27% , and the disease is well known for its protean manifestations [ 24 ] .
two non - mutually exclusive clinical and pathological patterns account for the great bulk of renal sarcoidosis , namely ( i ) nephrolithiasis and/or nephrocalcinosis - related to hypercalcaemia and hypercalciuria and ( ii ) interstitial nephritis with or without granulomatous formation [ 5 , 6 ] . in contrast
, renal vascular involvement is believed to be an exceptional complication of sarcoidosis and extensive retrospective series have failed to document any such complication [ 5 , 6 ] .
likewise , renal imaging findings are scanty and , if present , usually restricted to nephrocalcinosis , striated nephrograms or urinary tract obstruction [ 79 ] . here
we report the case of a 22-year - old patient in whom the manifestation of renal sarcoidosis consisted of severe hypertension associated with bilateral vascular lesions and granulomatous interstitial nephritis .
a 22-year - old white woman with a medical history of idiopathic epilepsy and sarcoidosis was referred to our institution for severe hypertension .
six months before her referral to our institution she had been diagnosed with sarcoidosis during the follow - up of clinical features consistent with lfgren 's syndrome . during diagnostic work - up ,
blood pressure ( bp ) was shown to be within normal ranges ( 128/66 mmhg ) .
corticosteroid therapy was considered unnecessary at that point and symptoms resolved within a couple of weeks . upon admission in our department ,
the patient 's bp was 169/123 mmhg under therapy of diltiazem 200 mg lp once daily , without clinical or echocardiographic repercussions .
( 68 mol / l , i.e. egfr = 98 ml / min/1.73 m , using the 4-variable mdrd [ modication of diet in renal disease ] ) formula .
haematuria and urine infection were excluded by dipstick examination and microalbuminuria was within physiological ranges ( 8 mg / l ) .
hormonal investigations , carried out under euvolaemic conditions , substantiated secondary hyperaldosteronism with elevated levels of plasma renin and aldosterone levels in the supine ( 75 mu / l and 31 ng / dl ; reference ranges 1025 and 2.814.4 , respectively ) and upright positions ( 298 mu / l ; and 2919 ng / dl ; reference ranges 1550 and 2001000 ) .
the 24-h urine aldosterone levels were high ( 2487 ng/24 h ; reference range 5051694 ) .
additional testing evidenced elevated levels of 25(oh ) vitamin d3 ( 85 nmol / l ; reference range 1157 ) but normal values of calcaemia ( 2.27
mmol / l ) , calcium urinary excretion ( 2.42 mmol / l ) and angiotensinogen - converting enzyme ( 11 mu / ml ) . an abdominal computed tomography scan ( ct ) revealed multiple bilateral wedge- and nodular - shaped hypodense foci affecting the renal cortex and medulla ( figure  1 ) , with no evidence of urinary tract obstruction .
renal angiography was prompted by persistent suspicion of underlying renal ischaemia : multiple cortical and sub - cortical vascular defects were evidenced in both kidneys ( figure  2 ) . in view of the equivocal nature of the lesions ,
there were no signs of vessel destruction or of small - vessel angeitis in this specimen , and the rest of the examination was unremarkable ( figure  3 ) . 

1.transverse contrast - enhanced abdominal ct during corticomedullary acquisition time displaying multiple , low - attenuation wedge - shaped foci seated in the cortex of both kidneys ( yellow arrows ) and low - attenuation corticomedullary nodules ( white arrowheads ) also present in both kidneys . 

2.selective left kidney angiography showing multiple cortical and sub - cortical vascular defects ( black arrows ) .
3.first renal biopsy demonstrating the presence of sarcoidosic granulomatous inflammation in the vicinity of two normal interlobular arteries ( masson trichrome , original magnification 200 ) .
transverse contrast - enhanced abdominal ct during corticomedullary acquisition time displaying multiple , low - attenuation wedge - shaped foci seated in the cortex of both kidneys ( yellow arrows ) and low - attenuation corticomedullary nodules ( white arrowheads ) also present in both kidneys .
selective left kidney angiography showing multiple cortical and sub - cortical vascular defects ( black arrows ) .
first renal biopsy demonstrating the presence of sarcoidosic granulomatous inflammation in the vicinity of two normal interlobular arteries ( masson trichrome , original magnification 200 ) .
the patient was subsequently started on tapering doses of prednisone ( 1 mg / kg / day ) and ramipril ( 5 mg once daily ) .
bp control was achieved and scr remained stable ( scr , 68 mol / l ; egfr , 98 ml / min/1.73 m ) .
an abdominal mri performed 9 months after the initiation of corticosteroid therapy exhibited only minimal cortical defects in both kidneys whereas the lesions located in the medulla had receded .
two years following the patient 's initial referral and progressive corticosteroid tapering , the patient presented with a recurrent bout of uveitis .
concurrently , renal impairment was evidenced ( scr , 126 mol / l ; egfr , 45 ml / min/1.73 m ) .
corticosteroids were reinitiated but proved to be unsuccessful as the patient 's kidney function failed to improve during the following year .
three years after initial referral , ct imaging ( figure  4 ) substantiated major bilateral cortical atrophy , predominant in the right kidney .
both kidneys displayed irregular contours with focal areas of cortical thinning where vascular defects had previously been noted .
there were also multiple left lateral aortic and caval lymph nodes , of increased size compared with the reference ct .
4.transverse contrast - enhanced abdominal ct during corticomedullary acquisition showing major bilateral kidney atrophy , predominant in the right kidney .
both kidneys displayed irregular contours with focal areas of cortical thinning where vascular defects had previously been noted ( white arrowheads ) .
note the presence of multiple left lateral aortic and caval lymph nodes ( yellow arrows ) .
transverse contrast - enhanced abdominal ct during corticomedullary acquisition showing major bilateral kidney atrophy , predominant in the right kidney .
both kidneys displayed irregular contours with focal areas of cortical thinning where vascular defects had previously been noted ( white arrowheads ) .
note the presence of multiple left lateral aortic and caval lymph nodes ( yellow arrows ) .
a 22-year - old white woman with a medical history of idiopathic epilepsy and sarcoidosis was referred to our institution for severe hypertension .
six months before her referral to our institution she had been diagnosed with sarcoidosis during the follow - up of clinical features consistent with lfgren 's syndrome . during diagnostic work - up ,
blood pressure ( bp ) was shown to be within normal ranges ( 128/66 mmhg ) .
corticosteroid therapy was considered unnecessary at that point and symptoms resolved within a couple of weeks . upon admission in our department ,
the patient 's bp was 169/123 mmhg under therapy of diltiazem 200 mg lp once daily , without clinical or echocardiographic repercussions .
( 68 mol / l , i.e. egfr = 98 ml / min/1.73 m , using the 4-variable mdrd [ modication of diet in renal disease ] ) formula .
haematuria and urine infection were excluded by dipstick examination and microalbuminuria was within physiological ranges ( 8 mg / l ) .
hormonal investigations , carried out under euvolaemic conditions , substantiated secondary hyperaldosteronism with elevated levels of plasma renin and aldosterone levels in the supine ( 75 mu / l and 31 ng / dl ; reference ranges 1025 and 2.814.4 , respectively ) and upright positions ( 298 mu / l ; and 2919 ng / dl ; reference ranges 1550 and 2001000 ) .
the 24-h urine aldosterone levels were high ( 2487 ng/24 h ; reference range 5051694 ) .
additional testing evidenced elevated levels of 25(oh ) vitamin d3 ( 85 nmol / l ; reference range 1157 ) but normal values of calcaemia ( 2.27
mmol / l ) , calcium urinary excretion ( 2.42 mmol / l ) and angiotensinogen - converting enzyme ( 11 mu / ml ) . an abdominal computed tomography scan ( ct ) revealed multiple bilateral wedge- and nodular - shaped hypodense foci affecting the renal cortex and medulla ( figure  1 ) , with no evidence of urinary tract obstruction .
renal angiography was prompted by persistent suspicion of underlying renal ischaemia : multiple cortical and sub - cortical vascular defects were evidenced in both kidneys ( figure  2 ) . in view of the equivocal nature of the lesions ,
there were no signs of vessel destruction or of small - vessel angeitis in this specimen , and the rest of the examination was unremarkable ( figure  3 ) . 

1.transverse contrast - enhanced abdominal ct during corticomedullary acquisition time displaying multiple , low - attenuation wedge - shaped foci seated in the cortex of both kidneys ( yellow arrows ) and low - attenuation corticomedullary nodules ( white arrowheads ) also present in both kidneys . 

2.selective left kidney angiography showing multiple cortical and sub - cortical vascular defects ( black arrows ) .
3.first renal biopsy demonstrating the presence of sarcoidosic granulomatous inflammation in the vicinity of two normal interlobular arteries ( masson trichrome , original magnification 200 ) .
transverse contrast - enhanced abdominal ct during corticomedullary acquisition time displaying multiple , low - attenuation wedge - shaped foci seated in the cortex of both kidneys ( yellow arrows ) and low - attenuation corticomedullary nodules ( white arrowheads ) also present in both kidneys .
selective left kidney angiography showing multiple cortical and sub - cortical vascular defects ( black arrows ) .
first renal biopsy demonstrating the presence of sarcoidosic granulomatous inflammation in the vicinity of two normal interlobular arteries ( masson trichrome , original magnification 200 ) .
the patient was subsequently started on tapering doses of prednisone ( 1 mg / kg / day ) and ramipril ( 5 mg once daily ) .
bp control was achieved and scr remained stable ( scr , 68 mol / l ; egfr , 98 ml / min/1.73 m ) .
an abdominal mri performed 9 months after the initiation of corticosteroid therapy exhibited only minimal cortical defects in both kidneys whereas the lesions located in the medulla had receded .
two years following the patient 's initial referral and progressive corticosteroid tapering , the patient presented with a recurrent bout of uveitis .
concurrently , renal impairment was evidenced ( scr , 126 mol / l ; egfr , 45 ml / min/1.73 m ) .
corticosteroids were reinitiated but proved to be unsuccessful as the patient 's kidney function failed to improve during the following year .
three years after initial referral , ct imaging ( figure  4 ) substantiated major bilateral cortical atrophy , predominant in the right kidney .
both kidneys displayed irregular contours with focal areas of cortical thinning where vascular defects had previously been noted .
there were also multiple left lateral aortic and caval lymph nodes , of increased size compared with the reference ct .
4.transverse contrast - enhanced abdominal ct during corticomedullary acquisition showing major bilateral kidney atrophy , predominant in the right kidney .
both kidneys displayed irregular contours with focal areas of cortical thinning where vascular defects had previously been noted ( white arrowheads ) .
note the presence of multiple left lateral aortic and caval lymph nodes ( yellow arrows ) .
transverse contrast - enhanced abdominal ct during corticomedullary acquisition showing major bilateral kidney atrophy , predominant in the right kidney . both kidneys displayed irregular contours with focal areas of cortical thinning where vascular defects had previously been noted ( white arrowheads ) .
note the presence of multiple left lateral aortic and caval lymph nodes ( yellow arrows ) .
this case reports an unusual presentation of renal sarcoidosis with prominent clinical features consisting of severe hypertension with bilateral vascular injury . despite a history strongly suggestive of sarcoidosis , renal biopsy
indeed , the presence of nodular corticomedullar - located hypodense foci entertained the possibility of a coexisting tumoural process .
only sparse case reports have documented this rare pseudonodular presentation [ 913 ] . in the even fewer instances where a renal biopsy was conducted ,
this lesional pattern was almost invariably related to extensive sarcoid granulomatous inflammation as in our case [ 1113 ] .
renal sarcoidosis is usually associated with marked renal impairment on presentation . nevertheless , in three cases of bilateral , 
pseudotumoral , renal sarcoidosis ( out of a total of four reports ) the initial kidney function was shown to be normal as in the case presented here [ 1315 ] .
renal pathology examination was also motivated by the triangular - shaped lesions located in the cortex which could be interpreted as post - ischaemic or evidence of infectious insults .
renal angiography ultimately confirmed the suspicion of renal ischaemia by demonstrating multiple vascular voids in the renal cortex and sub - cortex . although no pathological process involving the renal arterioles could be demonstrated on pathology , this may be ascribed to a sampling bias given the focal distribution of the renal perfusion defects .
regardless of the underlying mechanism , this process caused severe hypertension associated with secondary hyperaldosteronism and , in fine , widespread glomerular ischaemia and tubulointerstitial fibrosis .
although sarcoidosis is known to embrace a wide variety of clinical and pathological manifestations ( table  1 ) , this case is different from the other rarely reported clinical patterns consisting of severe hypertension associated with small and medium - vessel injury . aside from its rarity ,
sarcoidosis - induced vascular injury has been shown to involve all types of renal vessels . in most cases ,
renal vascular damage is but one of the multiple manifestations of multisystem vasculitis , a rare life - threatening complication associated with sarcoidosis . in the case of small and medium - sized vascular involvement
, the prominent clinical features also include pulmonary angiitis , cerebral vasculitis and skin sarcoidosis consistent with leukocytoclastic vasculitis and granulomatous vasculitis [ 17 , 18 ]
. large vessel damage may either present as renal artery stenosis with concurring severe hypertension   or aortic and renal aneurisms placing patients at high risk of subsequent rupture [ 18 , 20 ] .
in stark contrast , at no point of the disease process did we record any extra - renal vascular involvement .
furthermore , vascular wall involvement with elastic lamina dissolution  as exemplified by previous case reports  was not observed on pathological examination in our case [ 17 , 21 ] . 

table  1.summary of clinical and pathological patterns of renal sarcoidosispattern and/or cause of renal injuryfrequencyrenal function on presentationprominent laboratory featurespathological findings on kidney biopsyabdominal imaging findings ( on ct scan)granulomatous or non - granumolatous tubulointersititial nephritis+++altered , severe impairment is frequentmild proteinuria , microhematuria , sterile leukocyturia,+/ renal tubular acidosis+/ fanconi syndrometubulo - interstial nephritis+/ non necrotizing granuloma with epithelioid - like giant cells+/ schaumann bodiesnormal + + striated nephrogram + /pseudotumoral renal masses ( rare)nephrocalcinosis / nephrolithiasis++altered , severe impairment is frequenthypercalcaemia , hypercalciuria , elevated levels of 1 - 25(oh)vitd3+/renal tubular acidosis+/ fanconi syndromeintratubular and peritubular aggregation of calciumintrarenal calcifications+/ urinary obstructionglomerular diseaseraregenerally normal , mild to moderate impairment is possiblenephrotic range proteinuriamembranous nephritis + + + iga nephritis + + nrrenal vascular involvementvery rare??coexisting gin granuloma - associated vascular injuryrenal artery stenosis or aneurysmsmall- and medium - vessel occlusionmultisystem vascular involvementretroperitoneal fibrosisvery rare  ? ?
, no consistent data given the small number of cases ; a , most frequently described glomerular patterns ; gin , granulomatous interstitial nephritis ; nr , not relevant .
, no consistent data given the small number of cases ; a , most frequently described glomerular patterns ; gin , granulomatous interstitial nephritis ; nr , not relevant .
corticosteroids are regarded as the mainstay of renal sarcoidosis and retrospective studies have highlighted their effectiveness .
however , several pitfalls should be kept in mind : ( i ) reversal of renal impairment is not universal and some patients may require other immunosuppressive therapy such as azathioprine and mycophenolate mofetil , ( ii ) residual renal failure is common , and not all patients regain their baseline renal function , ( iii ) relapses are frequent on cortiscosteroid weaning although patients may respond on reinitiation of therapy and ( iv ) response to therapy is negatively correlated to the extent of renal fibrosis [ 6 , 22 ] .
however , by the time repeat imaging and biopsy were carried out the bilateral hypodense lesions thought to indicate the presence of granulomatous inflammation had resolved . instead
, these lesions had given way to extensive renal fibrosis and the reintroduction of corticosteroids was of no avail .
our case conveys further evidence that hypodense renal masses upon ct imaging may be regarded as a possible , albeit rare , manifestation of sarcoidosis .
it also suggests that renal ischaemia and hypertension may arise via extrinsic compression from granulomatous inflammation in the absence of renal or extra - renal vasculitis .
the occurrence of severe hypertension in a patient with a history of sarcoidosis should urge physicians to consider this complication .
a.h . and d.n . provided the expertise in the imaging and histopathological examinations , respectively .
c.r . undertook the data collection and analysis as well as the initial drafting of the report .
 renal sarcoidosis embraces a wide variety of clinical patterns . 
 renal vascular involvement has seldom been reported and usually in the setting of systemic vasculitis . 
 we report the case of a 22-year - old patient in whom inaugural manifestation of renal sarcoidosis consisted of severe hypertension associated with bilateral perfusion defects and tumour - like nodules . in the setting of renal sarcoidosis 
 , our case suggests that renin - dependant hypertension may arise from renal ischaemia as a result of extrinsic compression of kidney blood vessels due to severe granulomatous inflammation . 
Background
Case presentation
Clinical history
Follow-up
Discussion
Conclusion
Author's contributions