xanthogranulomatous pyelonephritis ( xgp ) is a rare , distinct and aggressive form of chronic infectious pyelonephritis . it accounts for lesser than 1% of chronic pyelonephritis . though common in fifth to sixth decade complications can occur in the form of psoas abscess , nephro cutaneous fistula , enterocolonic fistula , paranephric abscess and sepsis . it is essential to suspect and diagnose this condition early to prevent the morbidity and mortality . owing to its rarity and clinical curiosity a 75-year - old man presented with difficulty in micturition since 15 days , fever , abdominal and flank pain and burning micturition since 7 days . x - ray , ultrasonography ( usg ) and computed tomography ( ct ) scan abdomen findings include pyonephrosis and cortical atrophy in the right kidney . intravenous urography ( ivu ) revealed non - excretory right kidney . left kidney showed normal excretion resected specimen was yellowish lobulated renal mass measuring 13  8  6 cm with ureter [ figure 1a ] . cut section showed dilated pelvis , calyces and cortical atrophy due to extensive destruction of renal parenchyma , which were covered with thick purulent material [ figure 1b ] . histopathology revealed atrophic and dilated renal tubules showing thyroidisation and sclerosed glomeruli and interstitial fibrosis [ figure 2 ] . many areas showed histiocytes with abundant foamy cytoplasm , lymphoplasmacytic inflammatory cells with foci of polymorph nuclear leukocytes [ figure 3 and inset ] ziehl nelsen stain was negative for acid fast bacilli . ( a ) yellowish lobulated renal mass with ureter ; ( b ) dilated pelvis , calyces and cortical atrophy covered with thick purulent material atrophic and dilated renal tubules showing thyroidisation , sclerosed glomeruli and fibrosis . inset show giant cells and cholesterol clefts ( h and e , 400 ) foamy histiocytes , inflammatory cells . xgp is a severe chronic renal inflammatory condition leading to focal or diffuse kidney destruction . it may be due to defect in degradation of bacteria in the macrophages especially when associated with infection and obstruction by stones . three forms of xgp are recognised : diffuse  is characterized by diffuse involvement of kidney , segmental  by segmental involvement and focal - is located within the cortex . it is often misdiagnosed pre - operatively as pyelonephritis , tuberculosis , perinephric abscess and renal cell carcinoma ( rcc ) . symptoms include flank or abdominal pain , fever , palpable mass , gross hematuria , pyuria , dysuria and weight loss . in our case , symptoms were attributed to bph . other organisms include staphylococcus aureus , group b streptococcus , candida , klebsiella and bacteroides . elevation of serum creatinine and bun in our case can be attributed to impaired renal function . non - functioning , ct scan is the main stay of diagnostic imaging for xgp . xgp has been shown to be associated with transitional cell carcinoma of renal pelvis and rcc . they have even been reported in renal allograph . in diffuse or advanced stage xgp , nephrectomy is the treatment option . focal or segmental xgp if diagnosed early pre - operatively can be treated with antibiotics . pre- and post - operative broad spectrum antibiotics and symptomatic management are also key factors for successful management and better prognosis . we presented this unusual case of elderly male to stress the importance of through evaluation of renal function who gave a history of recurrent urinary tract obstruction and infection . chronic renal infection and obstruction are two common etiological factors for xgp . in all patients of prostatic enlargement , renal function must be assessed for the extent of damage . in non - functioning kidney
xanthogranulomatous pyelonephritis ( xgp ) is rare and aggressive form of chronic infectious pyelonephritis . 
 no single clinical or radiological feature is diagnostic of xgp . a 75-year - old man with prostatic enlargement presented with difficulty and burning micturition fever , abdominal and flank pain . 
 x - ray , ultrasonography and computed tomography scan diagnosis was right kidney pyonephrosis . 
 intravenous urography revealed non - excretory right kidney . 
 right nephrectomy was done . 
 histological diagnosis of xgp was made . in all patients of prostatic 
 enlargement , renal function must be assessed for the extent of damage . 
 surgery is the treatment choice in most cases . 
 pre- and post - operative antibiotics are key factors for successful management and better prognosis .