Kidney and Urinary Tract

Question 1

Nephrotic syndrome

Answer 1

• Group of conditions characterized by increased basement membrane permeability, permitting the urinary loss of plasma proteins
• Clinical; massive proteinuria, hypoalbuminemia, generalized edema, hyperlipidemia and hypercholesterolemia

Question 2

Minimal change disease (lipoid nephrosis)

Answer 2

• The prototype of the nephrotic syndrome
• Lipid-laden renal cortices
• EM: fusing of epithelial foot processes
• Responds well to adrenal steroid therapy

Question 3

Focal segmental glomerulosclerosis

Answer 3

• Major cause of nephrotic syndrome, clinically similar to MCD
• Characterized by sclerosis within capillary tufts of deep juxtamedullary glomeruli
• Focal distribution: some of the glomeruli
• Segmental distribution: part of the glomerulus
• Do not respond to steroids
• More common in African Americans
• Associated with HIV

Question 4

Membranous glomerulonephritis

Answer 4

• Major primary cause of the nephrotic syndrome - accompanied by azotemia
• Immune complex disease
• Thickened capillary walls
• Immune complexes in intramembranous and epimembranous locations within the BM
• “Spike and dome” appearance - stain
• Granular deposits of IgG or C3 - granular immunofluorescence
• Sometimes associated with; HBV, syphilis, malaria infection, drugs or malignancy

Question 5

Diabetic nephrophathy

Answer 5

• Clinically manifested by nephrotic syndrome
• Increase in mesangial matrix
  1) Diffuse glomerulosclerosis
  2) Nodular glomerulosclerosis

Question 6

Renal amyloidosis

Answer 6

• Cause of nephrotic syndrome
• Subendothelial and mesangial amyloid deposits
  1) Primary (AL) amyloidosis - in patients with plasma cell dyscrasias - monoclonal lambda light chains - most common type
  2) Secondary (AA) amyloidosis - in patins with long-standing neoplasia or inflammation - serum amyloid A protein

Question 7

Nephritic syndrome

Answer 7

• Characterized by inflammatory rupture of the glomerular capillaries - bleeding into the urinary space
• Clinical; Oliguria, azotemia, hypertension, hematuria (leakage of red cells directly from glomerular capillaries into Bowman space - red cell casts)

Question 8

Poststreptococcal glomerulonephritis

Answer 8

• Prototype of the nephritic syndrome
• Immune-complex disease - antigen of streptococcal origin - most often group A beta-hemolytic streptococci
• Lab; urinary red cells and red cell casts, azotemia, decreased serum C3, and increased titers of anti-streptococcal antibodies
• Electron-dense “humps” on epithelial side
• “Lumpy-bumpy” immunofluorescence

Question 9

Rapidly pregressive glomerulonephritis (RPGN)

Answer 9

• Nephritic syndrome that progresses rapidly to renal failure within weeks or months
• Formation of crescents between the Bowman capsule and the glomerular tuft - result from deposition of fibrin in the Bowman capsule and from proliferation of parietal epithelial cells of the Bowman capsule.
• Etiology: 50% - poststreptococcal - immune complex deposition

Type I: ANCA-negative - antiglomerular BM antibody
Type II: ANCA-negative - immune-complex type
Type III: ANCA-positive - antineutrophil cytoplasmic antibodies

Question 10

Goodpasture syndrome

Answer 10

• Cause: antibodies directed against antigens in glomerular and pulmonary alveolar BM
• IgG - linear immunofluorescence
• Clinical: nephritic syndrome, pneumonitis with hemoptysis, hematuria, RPGN crescentic morphology

Question 11

Focal glomerulonephritis

Answer 11

• Focal and segmental disease, but differs from focal segmental glomerulosclerosis in that the changes are inflammatory and proliferative rather than sclerotic
• Most often - immune complex disease

Question 12

Alport syndrome

Answer 12

• Hereditary nephritis
• Associated with nerve deafness and ocular disorders - lens dislocation and cataracts
• Clinical characteristics: nephritic syndrome progressing to end-stage renal disease by 30y
• Cause: mutation in the gene for the α5 chain of type IV collagen

Question 13

IgA nephropathy (Berger disease)

Answer 13

• Deposition of IgA in the mesangium
• Most frequently, the disease is characterized by benign recurrent hematuria in children, usually following an infection - 1 to 2 days
• Can be component of Henoch-Schönlein disease

Question 14

Membranoproliferative glomerulonephritis

Answer 14

• Clinical characteristic - slow progression to chronic renal disease
• BM thickening and cellular proliferation
• Reduplication of glomerular basement membrane into two layers - “tram-track” appearance

Type I: immune-complex nephritis - unknown antigen
Type II: dense deposit - IgG antibody with specificity for the C3 convertase

Question 15

Most common pathogen of urinary tract and kidney infection?

Answer 15

• Most frequently, the infection involves the normal flora of the colon, most often Escherichia coli
• Most common pathogen in young, sexually active woman is Staphylococcus saprophyticus

Question 16

Acute Pyelonephritis

Answer 16

• Infection of the renal parenchyma

- Fever, leukocytosis, flank tenderness, urinary white cells, and white cells casts in the urine

Question 17

Cystitis

Answer 17

• Infection of lower urinary tract - bladder

- Pyuria and often hematuria, but unitary white cell casts are not found.

Question 18

Acute tubular necrosis

Answer 18

• Most common cause of acute renal failure
• Revesible condition
• Can lead to cardiac standstill from hyperkalemia
• Precipitated by renal ischemia, caused by prolonged hypotension or shock - induced by gram-negative sepsis, trauma, or hemorrhage

Question 19

Fanconi syndrome

Answer 19

• Dysfunction of the proximal renal tubules
• May be hereditary or acquired
• Impaired reabsorption of glucose, amino acids, phosphate, and bicarbonate
• Clinical: glycosuria, hyperphosphaturia and hypophosphatemia, aminoaciduria, and systemic acidosis

Question 20

Cystinuria

Answer 20

• Impaired tubular reabsorption of cysteine

- Cystine stones

Question 21

Hartnup disease

Answer 21

• Impaired tubular reabsorption of tryptophan

- Leads to pellagra-like manifestations

Question 22

Chronic pyelonephritis

Answer 22

• Coarse, asymmetric corticomedullary scarring
• Interstitial inflammatory infiltrate –> interstitial fobrosis and tubular atrophy
• Causes: chronic urinary tract obstruction and repeted buts of acute inflammation

Question 23

Urolithiasis

Answer 23

• Characterized by calculi (stones) in the urinary tract
  A) Calcium stones - most common (80-85%) - calcium oxalate or/both calcium phosphate
  
  • Increased intestinal absorption of calcium
  • Increased primary excretion of calcium
  • Hypercalcemia –> caused by hyperparathyroidism, malignancy, sarcoidosis, vit. D intoxication, or milk-alkali syndrome
    B) Ammonium magnesium phosphate stones
    C) Uric acid stones
    D) Cystine stones

Question 24

Adult polycystic kidney disease

Answer 24

• Autosomal dominant inheritance
• Most comma inherited disorder of the kidney
• Partial replacement of renal parenchyma by cysts - bilaterally, enlarged kidneys
• Often associated with berry aneurysm of the circle of Willis
• Clinical: hypertension, hematuria, palpable renal masses, progression to renal failure

Question 25

Benign tumors of the kidney

Answer 25

• Adenoma - derived from renal tubules, may be precursor lesion to renal carcinoma
• Angiomyolipoma - hamartoma consisting of fat, smooth muscle, and blood vessels
• Oncocytoma - comprised of cells with abundant granular acidophilic cytoplasm replete with mitochondria

Question 26

Renal cell carcinoma

Answer 26

• Most common renal malignancy
• More common in men, higher incidence in cigarette smokers
• Gene deletions in chromosome 3
• Originates in renal tubules, most often arises in upper pole
• Frequently invade renal veins or the vena cava - early hematogenous dissemination
  1) Clear cell RCC - most common type
  2) Papillary RCC
  3) Chromophobe RCC
• Triad of flank pain, palpable mass, and hematuria (hematuria as the most frequent presenting sign)
• Fever, secondary polycythemia, ectopic production of carious hormones or hormone-line substances

Question 27

Wilms tumor (nephroblastoma)

Answer 27

• Most common renal malignancy of early childhood (peak 2-4 years of age)
• Originates from primitive metanephric tissue
• Palpable flank mass
• Deletions of short arm of chromosome 11. WT-1 and WT-2 genes - cancer suppressor genes.
• WAGR complex - Wilms tumor, Aniridia, Genitourinary malformations, and mental-motor Retardation –> WT-1 gene
• Hemihypertrophy (gross asymmetry of the body)
• Associated with Denys-Drash syndrome

Question 28

Transitional cell carcinoma

Answer 28

• Most common tumor of the urinary collecting system - renal calyces, pelvis, ureter, or bladder
• Often multifocal in origion - field effect
• Early sign is hematuria
• Marked tendency to recur after resection
• Tend to spread contiguously