Chapter 15: Renal Pathology

Renal Pathology review of renal pathology provides an in-depth analysis of kidney disorders, beginning with congenital anomalies such as renal agenesis, horseshoe kidney, and the distinction between autosomal recessive and autosomal dominant polycystic kidney diseases. The chapter extensively categorizes glomerular diseases into nephritic and nephrotic syndromes, detailing the pathogenesis, clinical presentation, and specific histological findings for each. Key nephritic conditions covered include acute poststreptococcal glomerulonephritis with its characteristic subepithelial humps, rapidly progressive glomerulonephritis (RPGN) associated with Goodpasture syndrome and crescent formation, IgA nephropathy (Berger disease), and Alport syndrome. The discussion on nephrotic syndrome, defined by proteinuria greater than 3.5 grams per day, explores membranous glomerulonephritis, minimal change disease involving podocyte foot process effacement, focal segmental glomerulosclerosis (FSGS), and membranoproliferative glomerulonephritis (MPGN) with its tram-track appearance. Secondary glomerular diseases, particularly diabetic nodular glomerulosclerosis (Kimmelstiel-Wilson syndrome) and systemic lupus erythematosus, are also examined. The text shifts to tubulointerstitial diseases, differentiating between acute and chronic pyelonephritis, drug-induced interstitial nephritis, and acute tubular injury (ATI), which is identified as a primary cause of acute renal failure marked by granular casts. Urolithiasis is broken down by stone composition, including calcium oxalate, struvite (staghorn calculi), uric acid, and cystine stones. Vascular pathologies such as renal artery stenosis and benign versus malignant nephrosclerosis are reviewed alongside renal infarction. Finally, the chapter outlines renal neoplasms, contrasting adult renal cell carcinoma and its paraneoplastic syndromes with the pediatric Wilms tumor, and concludes with urinary bladder pathologies, including cystitis and transitional cell carcinoma risks associated with smoking and chemical exposures.