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pauci - immune crescentic glomerulonephritis ( gn ) is one of the most common causes of rapidly progressive gn ( rpgn ) .
most patients with pauci - immune crescentic gn have glomerular disease as part of an antineutrophil cytoplasmic antibody ( anca)associated systemic vasculitis , such as granulomatosis with polyangiitis , microscopic polyangiitis ( mpa ) , and eosinophilic granulomatosis with polyangiitis , or as a part of renal - limited vasculitis . because ~7590% of patients with pauci - immune crescentic gn have circulating anca , anca is known as a major serologic marker to distinguish pauci - immune crescentic gn from other types of rpgn .
although there is little information about anca - negative pauci - immune crescentic gn owing to a relatively small number of patients , several studies have reported fewer systemic vasculitis manifestations in anca - negative crescentic gn than anca - positive cases .
hemorrhagic complications in pauci - immune crescentic gn are common , but massive gastrointestinal bleeding or cerebral hemorrhage in anca - negative pauci - immune crescentic gn has rarely been reported .
herein , we report a rare case of recurrent massive intestinal bleeding that was caused by an uncontrolled vasculitis combined with anca - negative pauci - immune crescentic gn .
a 61-year - old korean woman was admitted to our hospital with a 1-month history of generalized edema and foamy urine . on admission , she looked ill , and physical examination showed blood pressure 140/90  mmhg ; pulse rate 134 beats / min ; and temperature 37c . pitting edema greater than grade iii of the lower limbs was noted .
g / l ; platelets 277,000/mm ; blood urea nitrogen 54.5  mg / dl ; serum creatinine 3.5  mg / dl ; total protein 5.9  g / dl ; albumin 3.0  g / dl ; total calcium 8.4  g / dl ; phosphorus 5.0  mg / dl ; prothrombin time ( international normalized ratio ) 1.08 ; and activated partial thromboplastin time 34 seconds .
urinalysis revealed many red blood cells ( rbcs ) per high - power field , and protein ( 4 + ) and occult blood ( 2 + ) were also detected .
the spot urine protein - to - creatinine ratio was 3.5  g / g .
her renal function deteriorated rapidly over 7 days ( serum creatinine concentration increased from 3.5  mg / dl to 7.0  mg / dl ) and exhibited features of rpgn . therefore , we performed a renal biopsy and other serologic tests .
the serum immunoglobulin levels , including immunoglobulin ( ig)g , igm , and iga , and complements , including c3 and c4 , were within normal ranges .
the renal biopsy specimen showed cellular or fibrocellular crescentic formation in 92% ( 57/62 ) of glomeruli ( fig .
1 ) . the tubules revealed focal moderate atrophy and loss with infiltration of mononuclear cells in edematous interstitium .
immunohistochemistry , using three glomeruli , demonstrated no staining for igg , iga , igm , complements ( c3 , c1q ) , or fibrinogen .
electron microscopy also showed no dense deposits , with severe effacement of epithelial foot processes .
based on these pathologic findings , she was diagnosed with anca - negative pauci - immune crescentic gn .
the patient was treated with one cycle of steroid pulse therapy ( 500  mg of methylprednisolone daily , for 3 consecutive days ) with monthly intravenous cyclophosphamide ( 400  mg ) , followed by prednisolone ( 50  mg / d ) .
on the 15 hospital day , massive hematochezia occurred , and hemoglobin levels decreased from 9.2  mg / dl to 6.4  g / dl within 24 hours ( fig .
although emergency gastroscopy and colonoscopy were performed , the bleeding focus was not detected , but a large amount of old blood was observed in the terminal ileum .
after 2 days , a colonoscopy was performed again , but abnormal findings associated with bleeding were not detected .
then , a capsule endoscopy was attempted to determine if the bleeding focus was located in the small bowel . however , owing to a slow small bowel transit time , the entire small bowel could not be observed because the capsule did not reach the mid - to - distal ileum .
abdominal computed tomography angiography showed active arterial bleeding on the ileal loop , and selective superior mesenteric arteriography revealed an active contrast extravasation in a branch of the distal ileal artery ( fig .
3 ) . we selectively performed embolization with a permanent embolic agent ( n - butyl cyanoacrylate ; 0.5  ml tissue adhesive , 1.5  ml ethionidized oil mixture ) , and the bleeding stopped . despite successful embolization ,
her hemoglobin level was 6.5  g / dl , and platelet count was 40,000/mm .
emergency colonoscopy showed multiple segmental ulcerations on the terminal ileum , which was consistent with ischemic damage due to embolization of the distal ileal artery ( fig .
4 ) . the patient underwent hemodialysis because of intractable metabolic acidosis , hyperkalemia , and fluid overload . anemia associated with schistocytes and
transfusion - refractory consumptive thrombocytopenia was also present , consistent with microangiopathic hemolytic anemia ( maha ) .
levels of hemostatic markers showed prothrombin time ( international normalized ratio ) 1.00 ; activated partial thromboplastin time 33 seconds ; fibrinogen 399  mg / dl ; and fibrin degradation product < 5.0  g / ml . we ruled out disseminated intravascular coagulation using the international society on thrombosis and hemostasis disseminated intravascular coagulation scoring system . on the 45 hospital day , she suddenly lost consciousness .
the patients neurologic status had worsened to a stupor and then , unfortunately , she passed away .
the final diagnosis was anca - negative pauci - immune gn with a rare presentation of massive gastrointestinal bleeding and intracerebral hemorrhage .
pauci - immune crescentic gn is part of systemic small - vessel vasculitis and usually associated with the presence of ancas directed against myeloperoxidase or proteinase 3 .
although the pathogenesis of anca in vasculitis is not fully understood , anca is known to activate neutrophils by different mechanisms , such as direct fab02 binding to anca antigens on leukocyte surfaces or fc receptor engagement by anca immune complexes , leading to apoptosis and necrosis of neutrophil and endothelial cells . however , in anca - negative small - vessel vasculitis , neutrophil infiltration of the pathologic lesion is reportedly related with other unidentified autoantibodies or t - cell  dependent mechanisms . despite limited information about anca - negative pauci - immune crescentic gn , anca - negative patients reportedly show severe renal manifestations , such as nephrotic - range proteinuria , poorer renal outcomes , and less extrarenal involvement such as fever , arthralgia , skin rash , abdominal pain , or mononeuritis multiplex , compared with anca - positive patients [ 57 ] .
similarly , our case also showed nephrotic - range proteinuria of 3.5  g / d and diffuse cellular crescentic formations in > 90% of glomeruli on renal biopsy . initially , extrarenal manifestations were not observed .
our patient had no evidence of asthma , eosinophilia , or granuloma of the upper respiratory tract .
based on the 2012 international chapel hill consensus criteria , we were able to diagnose mpa and exclude granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis from the possible systemic small - vessel vasculitis conditions .
small - vessel vasculitis can cause local or diffuse pathologic changes in the gastrointestinal tract , including ulcers , bowel wall edema , hemorrhage , paralytic ileus , ischemia , obstruction , and perforation [ 912 ] .
although necrotizing gn and pulmonary capillaritis are very common in mpa , several cases with gastrointestinal bleeding have been reported .
interestingly , a japanese case diagnosed with mpa and pauci - immune crescentic gn showed active bleeding of the superior pancreaticoduodenal artery and iliac branch of the superior mesenteric artery .
the characteristics of this case were very similar to those of the present case : old age , absence of circulating anca , massive active bleeding , and absence of small artery involvement on kidney biopsy .
thrombotic microangiopathy is characterized by platelet aggregation in systemic circulation , thrombocytopenia , and mechanical hemolysis .
although coexistence of thrombotic microangiopathy and pauci - immune crescentic gn is rare , pauci - immune crescentic gn could trigger thrombotic microangiopathy through endothelial damage by proinflammatory mediators .
secondary ischemic multiple ulcerations after embolization , thrombocytopenia caused by consumption of platelets due to recurrent bleeding , and maha contribute to poor outcomes .
initiation of conventional treatment for pauci - immune crescentic gn with or without anca consists of intravenous methylprednisolone pulse therapy followed by progressive reduction of oral prednisolone ( initially 1  mg / kg/24  h ) and cyclophosphamide , either intravenously at a dose of 0.51  g / m or orally at a dose of 23  mg / kg/24  h . our patient received conventional treatment according to this schedule , but massive hematochezia occurred 15 days later . in life- or organ - threatening conditions , such as lung hemorrhage or severe anca - related renal vasculitis , plasma exchange may be recommended . in cases with gastrointestinal bleeding ,
therefore , our patient only received embolization without plasmapheresis or other immunosuppressants , based on previous reports .
although there was a high possibility of the hemorrhagic complications of systemic vasculitis , brain magnetic resonance angiography was not performed .
various factors that could increase bleeding tendency , such as a uremic condition , low platelet count , or frequent transfusions , may contribute to intracerebral bleeding . in summary , to the best of our knowledge , there are only a few reports regarding anca - negative pauci - immune crescentic gn with massive gastrointestinal bleeding .
therefore , the present case is interesting and informative , reporting recurrent massive intestinal bleeding and fatal intracerebral bleeding as a serious hemorrhagic complication of anca - negative pauci - immune gn .
a 61-year - old woman was admitted to hospital because of generalized edema and proteinuria . 
 her renal function deteriorated rapidly . 
 serum immunoglobulin and complement levels were within normal ranges . 
 an autoantibody examination showed negative for antinuclear antibody and antineutrophil cytoplasmic antibody . 
 histologic examination of a renal biopsy specimen revealed that all of the glomeruli had severe crescent formations with no immune deposits . 
 the patient was treated with steroid pulse therapy with cyclophosphamide followed by oral prednisolone . 
 fifteen days later , she experienced massive recurrent hematochezia . 
 angiography revealed an active contrast extravasation in a branch of the distal ileal artery . 
 we selectively embolized with a permanent embolic agent . on the 45th hospital day , 
 the patient suddenly lost consciousness . 
 brain computed tomography showed intracerebral hemorrhage . 
 we report a case of antineutrophil cytoplasmic antibody  
 negative pauci - immune glomerulonephritis with massive intestinal bleeding and cerebral hemorrhage .