Acute pyelonephritis. The cortical surface is studded with focal pale abscesses
discrete, yellowish, raised abscesses are grossly apparent on the renal surface
suppurative necrosis seen on M/E
Large masses of intratubular neutrophils frequently extend within involved nephrons into the collecting ducts, giving rise to the characteristic white cell casts found in the urine
papillary necrosis is a distinct subtype:
pyelonephritis with urinary tract obstruction
c/f: pain at the costovertebral angle and systemic evidence of infection, such as chills, fever, and malaise; indications of bladder and urethral irritation (dysuria, frequency, urgency)
Urinary findings include pyuria and bacteriuria.