although acute interstitial nephritis is a common cause of acute kidney injury , granulomatous interstitial nephritis ( gin ) remains a rare condition . in the report of mignon et al . besides drugs , other etiologies commonly associated with gin include , infections , immune processes , foreign body reaction , and some instances classified as idiopathic . there are not many published studies of gin , and none from the indian subcontinent . tuberculosis being endemic in india , the causative agents of gin is likely to be different from the other studies . the aim of the study was to analyze the etiology , clinical features and outcome of patients with biopsy - proven gin at our institute from january 2000 to october 2012 . all renal biopsy records from january 2000 to october 2012 were scrutinized for the diagnosis of gin . the clinical data were recorded from the case sheets of patients and also from outpatient ( op ) records of the discharged patients . the proforma included , the presenting history , past history , drug history , vital data , clinical examination , investigations , and management . all slides were stained with h and e , periodic acid - schiff , masson trichrome , silver and ziehl - neelsen stains . in all patients , aggregates of epithelioid histiocytes with or without giant cells within the interstitium or perivascular region were labeled as a granuloma . in addition , the nature of granuloma was assessed for the presence of necrosis , confluence with or without giant cells and schumann or asteroid bodies . patients with tuberculosis were treated with combinations of isoniazid ( 5 mg / kg / d ) , rifampin ( 10 mg / kg / d ) , pyrazinamide ( 10 mg / kg / d ) , ethambutol ( 5 mg / kg / d ) and levofolaxacin ( 15 mg / kg / q 48 h , post hemodialysis ) . for the first 3 months four drugs were prescribed and for the next 6 months two drug were continued . the age was 35  12 years , with a range of 20 - 70 years . the presenting serum creatinine was 6.7  3.8 ( range : 2.3 - 14.7 ) mg / dl . in nine patients tuberculosis was the causative agent . wegener 's granulomatosis , systemic lupus erythematosis ( sle ) , and immunoglobulin a nephropathy ( igan ) , were the associated conditions in one patient each . details of patients with granulomatous interstitial nephritis the number of glomeruli were 11.5  2.5 . the number of patients was too small for statistical analysis of pathologic features between etiologic groups . giant cells were present in all the patients , but with varying severity : scanty ( patient numbers : 3 , 5 , 7 , 8 , 10 , 14 ) to moderate ( patient numbers : 4 , 6 , 11 ) to plentiful ( patient numbers : 1,2,9,12,13 ) . sputum acid - fast bacilli ( afb ) were positive in two of them and chest radiograph revealed miliary pattern in one . the biopsy of the lymph node revealed caseating granuloma with afb on ziehl neelsen staining . in these four patients , the diagnosis of tuberculosis was made after renal biopsy revealed gin . in patients numbers 3 and 5 tuberculin skin test ( tst ) was ulcerated and in patient numbers 1 and 11 , tst was > 20 mm , suggesting tuberculosis . the serum calcium of all the patients was 8.8  1.2 ( range : 7.6 - 9.5 ) mg / dl . the four patients ( patient numbers : 7 , 8 , 11 , and 12 ) who required dialysis at presentation continued on dialysis . sle patient ( patient number 2 ) and wegener 's granulomatosis ( patient number 4 ) had responded to immunosuppression . the number of patients was too small for statistical analysis of pathologic features between etiologic groups . giant cells were present in all the patients , but with varying severity : scanty ( patient numbers : 3 , 5 , 7 , 8 , 10 , 14 ) to moderate ( patient numbers : 4 , 6 , 11 ) to plentiful ( patient numbers : 1,2,9,12,13 ) . sputum acid - fast bacilli ( afb ) were positive in two of them and chest radiograph revealed miliary pattern in one . the biopsy of the lymph node revealed caseating granuloma with afb on ziehl neelsen staining . in these four patients , the diagnosis of tuberculosis was made after renal biopsy revealed gin . in patients numbers 3 and 5 tuberculin skin test ( tst ) was ulcerated and in patient numbers 1 and 11 , tst was > 20 mm , suggesting tuberculosis . the serum calcium of all the patients was 8.8  1.2 ( range : 7.6 - 9.5 ) mg / dl . the four patients ( patient numbers : 7 , 8 , 11 , and 12 ) who required dialysis at presentation continued on dialysis . sle patient ( patient number 2 ) and wegener 's granulomatosis ( patient number 4 ) had responded to immunosuppression . finally , six patients were on conservative management for chronic renal failure . the age of patients was lower in our patients than these studies . while in our patients tuberculosis was a significant cause of gin , in the previous studies dugs and sarcoidosis were leading causes and a higher percentage of ( 42.8% , 6 out of 14 ) required renal replacement therapy ( rrt ) in our patients [ table 2 ] . javaud et al . , reported tuberculosis as a cause of gin in their series . sarcoidosis and tubulointerstitial nephritis with uveitis ( tinu ) were not found to be a causative factor in our series . all patients were investigated fully for all possible causes of gin , once granulomata were found in renal biopsy . igan presenting as gin was reported before , but except for one report all had a cause for igan . gin could be isolated or associated with the organ involvement orienting the diagnosis of underlying diagnosis . in the present study in seven patients tuberculosis was identified after gin was diagnosed on renal biopsy . in summary , gin is a rare cause of renal failure with multiple etiology , which are treatable . in indian subcontinent , tuberculosis is the most common etiology of gin . treatment of the underlying cause can reverse renal failure if it is not severe enough . in our study , many ( 42.8% ) had stage five chronic kidney diseases .
granulomatous interstitial nephritis ( gin ) is a rare condition . 
 drugs , infections , immune processes , and foreign body reaction are the main causes . 
 we identified a total of 14 patients with gin during a period of 13 years in 2798 renal biopsies . 
 there were 8 males and 6 females in the age range of 20 - 70 ( mean 35  12 ) years . 
 the serum creatinine at presentation was 6.7  3.8 ( range : 2.3 - 14.7 ) mg / dl . in nine patients tuberculosis was the causative agent . 
 drugs ( n = 2 ) and wegener 's granulomatosis ( n = 1 ) were other etiologies . systemic lupus erythematosis ( sle ) and immunoglobulin a nephropathy ( igan ) were seen in one patient each . 
 patients with tuberculosis were treated with antituberculous therapy and three of them improved . 
 four out of six patients who required dialysis at presentation remained dialysis dependent , one of whom underwent renal transplantation . 
 two patients progressed to end stage renal disease after 7 years and 9 years each . 
 the patients with drug induced gin had improvement in renal function after prednisolone treatment . 
 patients with sle , and wegener 's granulomatosis responded to immunosuppression . 
 patient with igan was on conservative management . 
 finally , six patients were on conservative management for chronic renal failure .