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Flashcards in Renal Deck (144)
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120

Horseshoe Kidney

  • fusion of upper or lower poles of kidneys ⇒ horseshoe-shaped structure continuous across midline anterior to great vessels.
    • most fused at lower pole (90%).

121

Multicystic Renal Dysplasia

  • persistence in the kidney  of abnormal structures: cartilage, undifferentiated mesenchyme, and immature collecting ductules: and by abnormal lobar organization.
  • associatead with ureteropelvic obstruction, ureteral agenesis or atresia, and anomalies of lower urinary tract.
  • dysplasia is uni or bilateral and cystic.
    • enlarged, irregular, and multicystic.  
    • cysts vary in size and lined by flattened epithelium.  
    • presence of islands of undifferentiated mesenchyme with cartilage and immature collecting ducts.
  • unilateral dysplasia discovered by appearance of flank mass, opposite kidney is normal.
  • bilateral multicystic renal dysplasia will go to renal failure.

122

Adult Polycystic Kidney Disease

  • autosomal dominant.  multiple expanding cysts of both kidneys that destroy renal parenchyma and cause renal failure.  systemic disease = cysts happen in other organs.
  • 1/400-1000 births.  need mutation of both alleles of PKD gene.
  • bilateral.  initially involve portions of nephrons ⇒ renal function good until 30-50yrs.
  • mutations of chromosome 16p13.1 (PKD1) and 4q21 (PKD2).
    • PKD1 is 85%.  severe disease, end-stage renal disease or death by age 53.  
    • age 69 for PKD2.
  • PKD1 encodes polycystin-1 an integral membrane protein in tubular epithelial cells in distal nephron.
  • PKD2 encodes polycystin-2, integral membrane protein in all segments of renal tubules and some extrarenal tissues.  functions as Ca-permeable cation channel so a defect ⇒ disrupted intracellular Ca level regulation.
  • defects in mechanosensing, Ca flux, and signal transduction underlie cyst formation.
  • polycystin 1 and 2 are located on primary cilium of tubular cells.  bending cilia allows Ca channels to open.
    • defect ⇒ no opening of Ca channels ⇒ changes in cellular proliferation, basal levels of apoptosis, interactions with ECM, and secretory function of epithelia.
    • ↑ proliferation and ↑ intraluminal fluid from ↑ secretion ⇒ cyst formation
  • morphology: bilaterally enlarged kidneys.  mass of cysts with no obvious parenchyma btw.
    • cysts filled with clear, serous fluid or turbid, red-brown hemorrhagic fluid.
    • arise from tubules and move toward calyces and pelvis ⇒ pressure defects.
    • lining of epithelium.
  • presentation: asymptomatic until renal insufficiency.
    • or pain from hemorrhage or dilation of cysts, hematuria, urinary tract infection, renal stones, HTN.
    • dragging sensation.
    • sometimes insidious onset hematuria with progressive chronic kidney disease (proteinuria, polyuria, HTN).
    • progression accelerated in blacks, males, and pts with HTN.
    • 40% have polycystic liver disease.
    • also can have intracranial berry aneurysms, mitral valve prolapse
    • 40% die of coronary of HTN heart disease, 25% of infection, 15% ruptured berry aneurysm or HTN intracerebral hemorrhage.

123

Childhood Polycystic Kidney Disease

  • autosomal recessive.  perinatal, neonatal, infantile, and juvenile forms.
    • perinatal and neonatal most common
  • caused by mutations of PKHD1 gene encoding fibrocystin.  highly expressed in adult/fetal kidney and liver and pancreas.
    • localized to primary cilium of tubular cells
  • morphology: kidneys enlarged with smooth surface.  numerous small cysts in cortex and medulla, looks spongelike.
    • dilated elongated channels perpendicular to cortical surface.  cylindrical dilation of collecting tubules.
    • cysts have uniform lining of cuboidal cells.
    • liver has cysts with portal fibrosis and proliferation of portal bile ducts.
  • survive infantile or juvenile form may ⇒ hepatic fibrosis with bland periportal fibrosis and proliferation of well-differentiated biliary ductules = congenital hepatic fibrosis.
  • may develop portal HTN with splenomegaly

124

Medullary Sponge Kidney

  • restricted to lesions consisting of multiple cystic dilations of collecting ducts in medulla.
  • in adults, incidental finding or from secondary complications: calcifications in dilated ducts, hematuria, infection, urinary calculi.  renal function normal.  
  • gross inspection: papillary ducts in medulla dilated, small cysts present.
    • cysts lined by cuboidal epithelium or transitional epithelium.  
    • cortical scarring absent unless have pyelonephritis.
  • features: hematuria, UTI, recurrent renal stones.

125

Nephronophthisis

  • variable number of cysts in medulla, concentrated at corticomedullary junction.
  • cortical tubulointerstitial damage causes renal insufficiency.
  • most genetic cause of end-stage renal disease in children and young adults.
  • juvenile form - NPH1, NPH2, NPH3 mutated.
    • present in primary cilia, basal bodies of the cilia, or centrosome organelle.
    • NPH1, NPH3-NPH6 = nephrocystins
    • NPH2 = inversin, mediates left-right patterning during embryogenesis 
  • 3 forms:
    • 1. sporadic/nonfamilial 
    • 2. familial juvenile nephronophthisis = most common.
      • autosomal recessive, manifest in childhood or adolescence.  
    • 3. renal-retinal dysplasia = as ocular lesions.
  • morphology: small kidneys with contracted granular surfaces and cysts in medulla (corticomedullary junction).  small cysts in cortex.
    • lined by flattened or cuboidal epithelium, surrounded by inflammatory cells or fibrous tissue.
    • widespread atrophy and basement membrane thickening of proximal and distal tubules in cortex.  interstitial fibrosis.  
  • in children or adolescents with unexplained chronic renal failure, family history, and chronic tubulointerstitial nephritis.
  • features: salt wasting, polyuria, growth retardation, anemia. defect in concentrating ability, tubular acidosis. can have ocular motor abnormalities, retinal dystrophy, liver fibrosis, and cerebellar abnormalities.  terminal renal failure in 5-10 yrs.

126

Adult-Onset Medullary Cystic Disease

  • variable number of cysts in medulla, concentrated at corticomedullary junction.
  • cortical tubulointerstitial damage causes renal insufficiency.
  • autosomal dominant.  mutation in MCKD1 and MCKD2.  progresses to end-stage kidney disease in adult life.
  • morphology: small kidneys with contracted granular surfaces and cysts in medulla (corticomedullary junction).  small cysts in cortex.
    • lined by flattened or cuboidal epithelium, surrounded by inflammatory cells or fibrous tissue.
    • widespread atrophy and basement membrane thickening of proximal and distal tubules in cortex.  interstitial fibrosis.  
  • features: salt wasting, polyuria.

127

Acquired (Dialysis-Associated) Cystic Disease

  • pts have end-stage renal disease, are on dialysis, and show numerous cortical and medullary cysts.
    • contain clear fluid, lined by hyperplastic or flattened tubular epithelium, contain calcium oxalate crystals.
    • form from obstruction of tubules by interstitial fibrosis or oxalate crystals.
  • presentation: mostly asymptomatic.  may have hematuria.  7% develop renal cell carcinoma.

128

Simple Cysts

  • multiple or single cortical cystic spaces usually 1-5cm in diameter.
  • translucent, lined by gray, glistening, smooth membrane, filled with clear fluid.  single layer of cuboidal or flattened cuboidal epithelium.  can be atrophic.  
  • usually post mortem findings.
  • if hemorrhage ⇒ sudden distension and pain, and bizarre radiographic shadows.
    • have smooth contours, are avascular, and show as fluid on ultrasound.

129

Obstructive Uropathy

  • ⇒ ↑ susceptibility to infection and stone formation.
  • unrelieved ⇒ hydronephrosis/obstructive uropathy = permanent renal atrophy.
  • can be sudden/insidious, partial/complete, uni/bilateral.
  • common causes:
    • congenital anomalies: posterior urethral valves and structures, meatal stenosis, bladder neck obstruction, ureteroplevic junction narrowing, vesicoureteral reflux.
    • urinary calculi
    • benign prostatic hypertrophy
    • tumors
    • inflammation
    • sloughed papillae or blood clots
    • pregnancy
    • uterine prolapse and cystocele
    • functional disorders: spinal cord damage, diabetic nephropathy, abnormalities or ureter or bladder.
  • hydronephrosis = dilation of renal pelvis and calyces associated with progressive atrophy of kidney from obstruction to outflow of urine.
    • high pressure in pelvis causes renal atrophy and causes dimunition in inner medullary blood flow.
    • also get interstitial fibrosis.
    • GFR decreases later on, have impaired concentrating ability.  
  • morphology: sudden and complete obstruction ⇒ ↓ GFR, mild dilation of pelvis/calyces, atrophy of renal parenchyma. 
    • subtotal/intermittent ⇒ normal GFR, progressive dilation.
    • kidney enlargred.  interstitial inflammation
    • chronic = cortical tubular atrophy with diffuse interstitial fibrosis.  progressive blunting of apices of pyramids, become cupped.
    • advanced = kidney thin-walled cystic structure with parenchymal atrophy, total obliteration of pyramids, thinning of cortex.
  • presentation:
    • acute = pain from distention, renal colic, prostatic enlargment ⇒ bladder symptoms.
    • unilateral complete/partial hydronephrosis = silent.  diagnose by ultrasound.
    • bilateral partial obstruction = inabiity to concentrate urine, polyuria, nocturia, distal tubular acidosis, salt wasting, secondary renal calculi, chronic tubulointerstitial nephritis with scarring and atrophy of papilla and medulla.  HTN.
    • complete bilateral obstruction = oliguria or anuria ⇒ death.  if relieved can have postobstructive diuresis (lose lots of sodium chloride).

130

Urolithiasis

  • men>women, ages 20-30yrs.  family predisposition.
  • 4 types:
    • 1. calcium stones (70%) 
    • 2. triple stones/struvite stones (15%)
    • 3. uric acid stones (5-10%)
    • 4. cystine stones (1-5%)
  • mucoprotein matrix in all stones.
  • could also be caused by deficiency in inhibitors of crystal formation in urine: pyrophosphate, diphosphate, citrate, glycosaminoglycans, osteopontin, nephrocalcin. 
  • determinant = ↑ urinary concentration of constituent, supersaturated.  can have low urine volume as well.
  • morphology: 80% unilateral.  usually in renal calyces and pelves and bladder.
    • renal pelvies - small stones, smooth or jagged.  
  • presentation: smaller stones produce colic with intense pain and ureteral obstruction.
    • larger stones remain silent in renal pelvis.
      • manifest by hematuria

131

Calcium Oxalate Calculi

  • 70% of calculi
  • calcium oxalate or mixed with calcium phosphate
  • 5% have hypercalcemia and hypercalciuria; 55% have hypercalciuria without hypercalcemia; 20% have hyperuricosuric calcium nephrolithiasis (↑ uric acid secretion).
  • 5% have hyperoxaluria from ↑ absorption; hypocitraturia with acidosis and chronic diarrhea ⇒ stones.
  • radiopaque

132

Magnesium Ammonium Phosphate Calculi

  • 15% of all calculi
  • Magnesium ammonium phosphate.
  • from bacteria (Proteus) which convert urea to ammonium ⇒ alkaline urine ⇒ precipitation.
  • forms large stones = staghorn calculi.  take up large part of renal pelvis.

133

Uric Acid Calculi

  • 5-10% of calculi
  • common with hyperuricemia (gout). 
  • 50% have neither hyperuricemia nor ↑ uric acid secretion.  have urine pH <5.5 ⇒ precipitate uric acid
  • radiolucent.

134

Cystine Calculi

  • 1-5% of calculi
  • from genetic defects in renal absorption of amino acids ⇒ cystinuria
  • get stones at low urinary pH.

135

Renal Papillary Ademona

  • small adenoma arising from renal tubular epithelium.
  • benign, usually found at autopsy.  
  • usually papillary
  • morphology: <0.5cm in diameter, in cortex, pale yellow-gray, discrete, well-circumscribed nodules.
    • made of complex, branching, papillomatous structues with complex fronds.
    • can grow as tubules, glands, cords, and sheets.
    • cuboidal to polygonal cells in shape, regular small central nuclei, scanty cytoplasm, no atypia.
    • have trisomy 7 and 17.  
    • 3cm is cutoff for metastases.

136

Angiomyolipoma

  • benign, made of vessels, smooth muscle, and fat.
  • in 25-50% pts with tuberous sclerosis = loss of function mutation in TSC1 or TSC2 tumor suppressor genes.
  • lesions of cerebral cortex ⇒ epilepsy, mental retardation, skin abnormalities, and benign tumors.
  • susceptible to spontaneous hemorrhage.

137

Oncocytoma

  • benign epithelial tumor of large eosinophilic cells with small round nuclei and large nucleoli.
  • numerous mitochondria.
  • gross: tan or mahogany brown, homogeneous, well encapsulated. up to 12cm in diameter.
  • can be familial = multicenteric.

138

Renal Cell Carcinoma

  • in older people (50-70yrs), 2:1 men:women.
  • arise from tubular epithelium.
  • risk factors: tobacco**, obesity, HTN, estrogen therapy, asbestos, petroleum, heavy metals, tuberous sclerosis, acquired cystic disease, chronic renal failure.
  • usually sporadic but can be autosomal dominant.
    • Von Hippel-Lindau syndrome - in familial and sporadic clear cell tumors.
    • Familial clear cell carcinoma
    • Hereditary papillary carcinoma -multiple bilateral tumors with papillary histology.  mutated MET.
  • types:
    • clear cell carcinoma (70-80%)
    • papillary carcinoma (10-15%)
    • chromophobe renal carcinoma (5%)
    • collecting duct (Bellini duct) carcinoma (<1%)
  • morphology: usually at the poles.  tendency to invade the renal vein and grow as solid column of cells in vessel.  can extend to right side of heart.
  • presentation: costrovertebral pain, palpable mass, and hematuria seen in 10% of cases.  hematuria most reliable.
    • general symptoms: fever, malaise, weakness, weight loss. 
    • paraneoplastic syndromes: polycythemia, hypercalcemia, HTN, hepatic dysfunction, feminization or masculinization, Cushing syndrome, eosinophilia, leukomoid rxn, amyloidosis.
    • tendency to metastasize widely before have symptoms.
      • metastasizes to: lungs, bones, regional lymph nodes, liver, adrenal, and brain.
  • prognosis: 5 year survival 45%.  15-20% with renal vein invasion.  70% without distant metastases.
  • tx: nephrectomy.

139

Clear Cell Carcinoma

  • 70-80% renal cell carcinomas
  • nonpapillary cells, clear or granular cytoplasm.  95% sporadic. associated with VHL on chromosome 3 (deletion or somatic mutation or hypermethylation)
  • VHL encodes protein in ubiquitin ligase complex, mutation ⇒ ↑ HIF-1 ⇒ ↑ VEGF, PDGF, TGF-alpha, TGF-beta.  upregulation of insulin-like growth factor 1.
  • arises from proximal tubular epithelium.
  • solitary unilateral lesion, spherical.  bright yellow-gray-white tissue, distorts renal outline.  yellow = prominent lipid accumulation in tumor cells.
  • large areas of ischemic, opaue, gray-white necrosis and foci of hemorrhage. 
  • margins sharply defined and confined in capsule.
  • growth pattern can be trabecular or tubular.
  • tumor cells rounded or polygonal shape with clear or granular cytoplasm (glycogen and lipids).
  • branching vasculature, cysts, and solid areas.
  • most are well differentiated but some have nuclear atypia with bizarre nuclei and giant cells.

140

Papillary Carcinoma

  • 10-15% renal cell carcinomas
  • papillary growth pattern, familial and sporadic.
  • sporadic = trisomies 7, 16, 17, and loss of Y in males
  • familial = trisomy 7.
  • MET on chromosome 7 = receptor for hepatocyte growth factor.
  • multifocal in origin, bilateral.
  • from distal convoluted tubules.
  • hemorrhagic and cystic.
  • most common type in those with acquired cystic disease.
  • cuboidal or low columnar cells in papilary formations.
  • interstitial foam cells in papillary cores.  psammoma bodies.
  • little stroma but highly vascularized.

141

Chromophobe Renal Carcinoma

  • 5% renal cell carcinomas
  • made of cells with prominent cell membranes and pale eosinophilic cytoplasm with halo around nucleus.
  • arranged in solid sheets with concentration of largest cells around blood vessels.
  • multiple chromosome losses and extreme hypodiploidy.
  • grow from intercalaed cells of collecting ducts
  • good prognosis.
  • hard to distinguish from oncocytoma.

142

Collecting Duct Carcinoma

  • <1% renal cell carcinomas
  • from collecting duct cells in medulla.
  • characterized by nests of malignant cells enmeshed within prominent fibrotic stroma (medullary).
  • irregular channels lined by atypical epithelium with hobnail pattern.

143

Urothelial Carcinomas of Renal Pelvis

  • 5-10% of renal tumors come from urothelium of renal pelvis.
  • produce hematuria quickly, small when discovered.
  • block urinary outflow and cause palpable hydronephrosis and flank pain.
  • can involve pelvis, ureters, bladder.
    • 50% have preexisting bladder urothelial tumor.
  • foci of atypia or carcinoma in situ in urothelium remote from renal pelvis and bladder in pts with analgesic nephropathy and Balkan nephropathy.
  • infiltration of pelvic wall and calcyes is common.
  • presentation: flank pain, hydronephrosis, hematuria.
  • poor prognosis.