December 3, 2018
Diagnose This (December 3, 2018)
What is your diagnosis? What would you want to confirm your diagnosis?
The photo shows a fibrocellular crescent dissecting through the center of a glomerulus. In the peripheral portions of the glomerulus no obvious endocapillary proliferation is present, but the glomerulus is so disrupted that this evaluation is made difficult. Overall, the findings are most suggested of an ANCA-mediated or endocarditis-associated glomerulonephritis. However, to resolve this we will need immunofluorescence and electron microscopy. For ANCA-mediated disease we would expect minimal to no immune complex deposition and minimal to no immune complex deposits on electron microscopy. Endocarditis-associated glomerulonephritis can have findings very similar to ANCA-mediated disease however, C3 is prominent by immunofluorescence in these cases and endocapillary proliferation and/or IgG deposition is also seen in around 30% of these patients. Additionally, in endocarditis-associated glomerulonephritis deposits tend to be mesangial and subendothelial by electron microscopy and subepithelial humps are uncommon.