The vesicoureteral junction. In normal individuals (A), the intravesical portion of the ureter is oblique, such that the ureter is closed by muscle contraction during micturition. The most common cause of reflux is congenital complete or partial absence of the intravesical ureter (B).
Vesicoureteral reflux
Vesicoureteral reflux demonstrated by a voiding cystourethrogram. Dye injected into the bladder refluxes into both dilated ureters, filling the pelvis and calyces.
Rt. The cortical surface is studded with focal pale abscesses, more numerous in the upper pole and middle region of the kidney; the lower pole is relatively unaffected. Between the abscesses there is dark congestion of the renal surface. Lt. Cut section showing multiple small yellow abscess mainly in the cortex but also in the medulla. Note the markedly congested parenchyma & pelvic mucosa.
Acute pyelonephritis
There is intense acute neutrophilic infiltration within tubules and the renal substance.
Acute PyelonephritisAreas of pale gray necrosis are limited to the papillae. The distal part of each pyramid is greyish white and necrotic.
Papillary necrosis
Typical coarse scars of chronic pyelonephritis associated with vesicoureteral reflux. The scars are usually located at the upper or lower poles of the kidney and are associated with underlying blunted calyces.
Chronic pyelonephritis
The cortical surface shows coarse depressed scars, each with greyish-white center.
There is a large collection of chronic inflammatory cells associated with fibrosis that involves the interstitum & periglomerular areas (arrow). This biopsy is from here a patient with a history of multiple recurrent urinary tract infections.
Chronic pyelonephritis
Both lymphocytes and plasma cells are seen at high magnification in this case of chronic pyelonephritis. It is not uncommon to see lymphocytes accompany just about any chronic renal disease: glomerulonephritis, nephrosclerosis, pyelonephritis. However, the plasma cells (arrows) are most characteristic for chronic pyelonephritis.
Chronic pyelonephritis
There is prominent eosinophilic and mononuclear infiltrate of the interstitium
Acute drug-induced tubulo-interstitial nephritisThere is prominent vacuolization of tubular epithelial cells. Some tubules show epithelial sloughing & regeneration (arrow).
Toxic Acute tubular necrosis due to ethylene glycol poisoning