70-year-old male. Rapidly progressive renal failure (within 2 months) with haematuria and proteinuria. The patient declines dialysis and dies of uraemia. Autopsy specimen.
- All glomeruli are changed and show extracapillary proliferation (half-moon shape). These structures consist of proliferating parietal epithelium and inflammatory cells (histiocytes, neutophils) and fill the rim of the capsule. Some are cellular (recent), some fibrocellular and some fibrous (older lesions). There are also fresh lesions with fibrin exudate seeping into the capsule area. There is an extensive periglomerular inflammatory reaction with numerous neutrophilic granulocytes. Also note the acute pyelonephritis.
Pathogenesis: The extracapillary proliferation occurs when the glomerular capillary slings are damaged. The leakage of fibrin generates a path for infiltration with histiocytes and granulocytes. Causes include immune complex glomerulonephritis, anti-basal-membrane-antibody disease and ANCA- (antineutrophil-cytoplasmic antibody) positive glomerular vasculitiss.
The prognosis depends on the extent of glomerular destruction. Cases with extensive damage such as this are described as rapidly progressive glomerulonephritis.