WBC casts
WBC casts (black arrows) in a biopsy specimen of a patient with acute interstitial nephritis. Images courtesy of Patrick Walker, MD.
Autosomal recessive polycystic kidney disease (ARPKD)
Gross pathology and low-power light microscopy of kidney tissue in a neonate with ARPKD. The kidneys are enlarged but maintain their reniform shape, and are full of microscopic cysts derived from dilated distal tubules and cortical collecting ducts. Images courtesy of Patrick Walker, MD.
Simple renal cysts
Microscopic renal cysts. Note the flattened to cuboidal epithelium lining the cysts. Images courtesy of Patrick Walker, MD.
Crescents
A segmental (left, black arrow) and circumferential crescent (right) in a patient with IgA nephropathy. Images courtesy of Patrick Walker, MD.
Endocapillary hypercellularity
A normal appearing glomerulus (left) compared to a glomerulus with endocapillary hypercellularity (right). Note the hypercellular capillary loop (red arrow) compared to the normal capillary lumens (black arrows). This histologic feature can be seen in several glomerular disorders, including IgA nephropathy, post-infectious glomerulonephritis, lupus nephritis, and C3 glomerulopathy. Images courtesy of Patrick Walker, MD.
Immunofluorescent staining in C3 glomerulopathy
Immunofluorescent staining pattern in a patient with C3 glomerulopathy. There is strong C3 staining in the capillary loops and mesangium. Immunoglobulin staining, such as IgG, is typically absent or at a lower intensity by at least two orders of magnitude than C3. Images courtesy of Patrick Walker, MD.
Dense deposit disease
Dense deposit disease on electron microscopy in a patient with C3 glomerulopathy. This lesion results from intramembranous transformation of the glomerular basement membrane by sausage-like, “osmiophilic” dense material. Images courtesy of Patrick Walker, MD.
Membranoproliferative glomerulonephritis
Membranoproliferative pattern of glomerular injury in a patient with C3 glomerulopathy. This pattern of injury typically has endocapillary proliferation, diffuse capillary wall thickening, increased mesangial matrix, and mesangial proliferation visible on light microscopy, producing a lobular appearance of the glomerular tuft. Images courtesy of Patrick Walker, MD.
Foam Cells
Clusters of interstitial foam cells (arrows) in a kidney biopsy. These are commonly found in biopsy specimens of patients with Alport syndrome, FSGS, IgA nephropathy, and other proteinuric kidney diseases. Image courtesy of Patrick Walker, MD.