Infective Endocarditis-Associated Glomerulonephritis: A Report of 37 Cases
Christie L Boils, Samih H Nasr, Patrick D Walker, Christopher P Larsen. Nephropathology Associates, Little Rock, AR; Mayo Clinic, Rochester, MN
Background: Endocarditis-associated glomerulonephritis was first described over a century ago, with most literature originating from autopsy specimens during the pre-antibiotic era. In order to better define the morphologic spectrum of this entity, we report the largest case series of infective endocarditis-associated glomerulonephritis.
Design: In this collaborative multi-center retrospective review, thirty-seven patients with a renal biopsy showing glomerulonephritis in the setting of infective endocarditis were identified. All cases were processed by routine light, immunofluorescence and electron microscopy.
Results: The study group included 31 men and 6 women with a mean age of 49 years (range 3 to 84). Predisposing states for endocarditis included a prosthetic valve or ventriculoatrial shunt (28%), intravenous drug use (24%), hepatitis C infection (24%) and valve prolapse or insufficiency (16%). Endocarditis most commonly involved the tricuspid valve (30%) and identified Staphylococcus species on culture. Of the patients tested for ANCA, 63% were negative, 25% were positive, and 13% were equivocal. Serum complement testing was normal in 50% of patients tested. The most common morphologic pattern was diffuse crescentic glomerulonephritis (38%) followed by equal numbers of focal crescentic glomerulonephritis (22%) and diffuse proliferative glomerulonephritis showing endocapillary hypercellularity (22%). Absent or pauci-immune staining for all immunoglobulins was noted in 65% of cases, of which 63% revealed focal or diffuse crescentic glomerulonephritis morphologically. Subepithelial humps were noted by electron microscopy in only 16% of cases.
Conclusions: The majority of patients had renal biopsy findings that were not classic for an infection-associated glomerulonephritis, but rather manifested as pauci-immune crescentic glomerulonephritis. These cases would have been morphologically and clinically suspicious for ANCA-associated glomerulonephritis if the presence of endocarditis was unknown. Positive ANCA serology does not exclude the possibility of endocarditis-associated glomerulonephritis as 38% in this series were either equivocal or positive for ANCA. Also in contrast to the typical infection-associated glomerulonephritis, half of patients tested for serum complement had normal C3 and C4 levels. It is important for the practicing nephrologist and renal pathologist alike to maintain a high index of suspicion for this entity considering the potential adverse outcome if a patient with endocarditis were to be treated with cytotoxic agents in lieu of antibiotics.
Category: Kidney (does not include tumors)
Monday, March 19, 2012 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 252, Monday Morning