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Paper text:
atheroembolic renal disease ( aerd ) is defined as renal failure secondary to the occlusion of renal vasculature by cholesterol containing atheromatous plaques dislodged from the aorta or other major arteries .
this occurs either spontaneously , or following invasive vascular procedures such as angiographic catheter insertions , or after the use of anticoagulant and thrombolytic agents .
aerd is often not suspected clinically , and mimics as well as coexists with several other systemic diseases . in spite of advances in imaging modalities and clinical experience with this entity since its first description in 1862 , several issues regarding its diagnosis and management still remain unresolved .
a 73-year - old - man with 40 pack years of smoking history and hypertension was on treatment with amlodipine 5 mg per day .
he was diagnosed with peripheral vascular disease when a surgical consultation for purplish discoloration of toes was sought 3 months ago [ figure 1a ] and warfarin sodium 5.0 mg alternating with 2.5 mg per day was prescribed .
( a ) clinical photograph of the patient showing the purplish discoloration of the toes .
( b ) photomicrograph of renal biopsy showing the characteristic biconcave needle shaped cholesterol atheroemboli lodged in an interlobular sized artery ( h and e , 400 ) in the current admission , he presented with passage of black stools and fresh bleeding per rectum .
warfarin was stopped and an upper gastrointestinal endoscopic examination was performed , which showed a healed duodenal ulcer .
urine output was adequate on the first two days of admission ( about 1800 ml ) and urine examination at this time showed trace proteinuria , 8 - 10 pus cells / hpf .
there was no evidence of hematuria or heme granular casts on microscopic examination of urine sediment . on the third admission day
, he developed abrupt swelling of both legs and sharp decline in urine output to 600 ml which further dropped to 400 ml on fourth day , with development of azotemia .
pending the results of serological investigations , a clinical suspicion of vasculitis was considered and three doses of injection methyl prednisolone 1 gm intravenous daily for three days were administered starting from fifth admission day , followed by oral prednisolone 60 mg per day from 4 day .
a renal biopsy was meanwhile performed which revealed presence of biconvex needle shaped empty spaces in lumen of an interlobular sized artery , consistent with cholesterol atheroemboli [ figure 1b ] .
tubular atrophy and interstitial fibrosis involved about 40% of the cortex , and the proximal tubules in the viable areas showed features of acute tubular injury , including loss of brush borders , epithelial simplification luminal granular casts .
direct immunofluorescence examination was negative for immunoglobulins ( iga , igg , igm ) , complements ( c3 , c1q ) , and also for kappa and lambda light chains .
no refractile crystals were noted in frozen sections of biopsy core submitted for direct immunofluoroscence ( dif ) studies . a final diagnosis of renal failure secondary to atheroembolic renal disease possibly precipitated by oral anticoagulant therapy was rendered .
laboratory parameters at presentation patient 's clinical status gradually improved with progressive increase in urine output and reduction of serum creatinine to 2.3 mg / dl on 21 post admission day [ figure 2 ] .
after review of kidney biopsy report , the oral prednisolone was tapered rapidly in 2 weeks , and cyclophosphamide was withdrawn .
hemodialysis was discontinued and patient was discharged , off dialysis in a clinically stable condition with advice for regular outpatient follow - up .
aerd is a part of systemic disease triggered by the release of cholesterol emboli from a disrupted atheromatous plaque usually located in the aorta to several organs .
renal involvement is frequent owing to their anatomical proximity to the aorta and high rate of perfusion .
incidence of aerd is difficult to estimate as it is often underdiagnosed owing to its propensity to coexist with as well as mimic several other renal disorders .
the reported incidence in biopsy series varies from 1.1% to 4.5% in various studies and an approximately similar incidence in few autopsy studies .
the classic clinical manifestations of aerd include live do reticularis ( purplish rash over lower extremities and abdominal wall ) , purple toes , small nail bed infarcts and various other manifestations related to lodgement of atheroemboli in other organs such as muscles ( myalgia ) , joints ( arthralgias ) , pancreas ( acute pancreatitis ) gastrointestinal tract ( perforation ) or the eye ( retinal infarction ) .
it is worth noting that many of these manifestations are also associated with systemic vasculitis , which is often the first clinical differential diagnosis in patients with aerd , as in the present case .
a further diagnostic difficulty arises in patients with pre - existing peripheral vascular disease , wherein livideo reticularis may be mistaken for manifestations of peripheral vascular disease , leading to a delay in diagnosis of the condition . in the present case ,
the finding of live do reticularis ( purplish discoloration of lower extremities and toes ) , was ascribed to peripheral vascular disease , and oral anticoagulants were prescribed , which possibly led to the sequence of events culminating in aerd .
aerd has a variable , but definite temporal relationship to invasive vascular procedures and use of thrombolytic and anticoagulant therapy .
overall , it is estimated that about 30 - 85% of patients with aerd have a history of invasive vascular procedure in the preceding 3 months .
studies have shown that about 13 - 22% patients with aerd received anticoagulant therapy ( heparin or warfarin ) , as noted in the present case .
the mechanism involves dissolution of superficial clots which destabilize the ruptured atherosclerotic plaques , resulting in showering of cholesterol atheroemboli into the circulation .
the gold standard of diagnosing aerd remains the demonstration of atheroemboli in renal vasculature in a renal biopsy .
delay or failure to diagnose this condition often stems from hesitation to perform renal biopsies , as the patients are elderly and have compromised kidneys due to co - existing morbidities .
ghosts  . involvement of renal vasculature is patchy , and the diagnosis may be missed if few sections are examined in a biopsy . in the present case
also the emboli were visualized in only three of the 43 sections examined , and were also absent from the tissue submitted for immunofluorescence examination .
surgical management includes repair of aortic aneurysms , interposition of prosthetic bypass graft , angioplasty or extracorporeal arterial reconstruction .
few studies have demonstrated the benefits of pulse steroid therapy in patients with aerd.[912 ] we noted a steady improvement in patient 's clinical condition and renal parameters following pulse steroid therapy .
although successful treatment of aerd using both high ( intravenous pulse steroids ) and low dose ( 0.3 mg / kg / day ) corticosteroids has been reported , a careful approach is necessary as both these therapeutic options may predispose the patients ( who frequently suffer from significant co - morbidities ) to infectious complications .
the rationale behind use of steroids in aerd is not clear , but may be related to the suppression of reactive inflammation often seen along with the atheromatous plaques .
activation of the complement ( c5 ) in vitro along with evidence of hypocomplementemia and eosinophilia in many patients suggest a possible role for inflammation in pathogenesis of aerd and , perhaps the response to steroid therapy .
outcome of aerd is generally considered poor with high mortality rate . in a large study , older age , comorbid conditions ( presence of diabetes and history of heart failure ) ,
baseline renal dysfunction , time course of renal function decline , and extra renal manifestations were associated with a significant increased risk for both esrd and death .
a greater awareness regarding its clinical manifestations is essential and in the relevant clinical setting , a timely performed renal biopsy can allow early diagnosis and initiation of appropriate treatment .
pulse steroid therapy appears to be an effective modality and may be offered as a first line treatment in patients with aerd .
atheroembolic renal disease is characterized by renal failure secondary to occlusion of renal vasculature by cholesterol containing atheromatous plaques . 
 clinical presentations of this disease entity are myriad , with limited therapeutic options and unfavorable outcomes . 
 this report describes an elderly male patient with peripheral vascular disease who developed acute renal failure during hospital admission for rectal bleed , and was diagnosed with atheroembolic renal disease on renal biopsy . 
 the patient was managed with pulse steroid therapy and had a favorable outcome .