Abstract: SA-PO697
Clinicopathologic Features and Outcomes of Endocarditis-Associated Glomerulonephritis (ECGN)
Session Information
- Pathology and Lab Medicine: Clinical
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1602 Pathology and Lab Medicine: Clinical
Authors
- Nguyen, Jane K., Cleveland Clinic, Cleveland, Ohio, United States
- Herlitz, Leal C., Cleveland Clinic, Cleveland, Ohio, United States
Background
ECGN is a well-documented entity but may be under recognized due to its overlapping features with other glomerulonephridities. The aim of this study was to analyze clinical and pathologic characteristics of patients with ECGN.
Methods
Clinical and renal histopathologic data of 12 patients from a single center with biopsy-proven ECGN from 2009 to 2019 were retrospectively analyzed.
Results
Among the 12 patients with ECGN, all presented with acute kidney injury, the male-to-female ratio was 5:1 and mean age was 60 years. Mean serum creatinine at the time of presentation was 4.8 mg/dL. On urine dipstick, 92% of the patients presented with at least 2+ hematuria and 84% had 1+ proteinuria. There were no known cardiac abnormalities in 7 of 12 patients. The most common comorbidities were cardiac valve disease (42%), intravenous drug abuse (17%), and hepatitis C (8%). Infective bacteria were Bartonella (5/12), Staphylococcus (4/12), Enterococcus (2/12) and Streptococcus (1/12). All cases associated with hypocomplementemia (5/10) and/or ANCA antibody (5/10) in the patients tested were found in association with the following bacteria: Bartonella, Enterococcus or Streptococcus viridans. Cryoglobulins were positive in 9 of 11 patients tested. Light microscopy showed either focal or diffuse endocapillary proliferative features in 92% of the cases and 83% of cases showed at least focal necrotizing crescent formation. An active tubulointerstitial infiltrate was seen in 67% of the cases. No cases showed arteritis. Immunofluorescence revealed either dominant or co-dominant C3 staining (10/12 cases) and IgM was the most commonly deposited immunoglobulin with polyclonal 2-3+ staining seen in 58% of the cases. Strong IgM staining was associated with all tested cases of Bartonella (5), Enterococcus (1) and Streptococcus (1). Treatment included long term antibiotics (12/12), heart valve replacement (6/12), immunosuppression (4/12) and dialysis (4/12).
Conclusion
ECGN most commonly presents with AKI. Particularly in subacute endocarditis, positive ANCA serologies and biopsy findings of crescentic GN can lead to missed diagnosis. Strong staining for IgM as well as C3 was seen commonly in cases of ECGN associated with Bartonella and other subacute organisms. A high index of suspicion on renal biopsy was important to timely diagnosis as Bartonella is not detectable on routine blood culture.