Renal - Pathology (2) Flashcards

1
Q

Hydronephrosis

  • Definition
  • Due to…
  • Findings
A
  • Definition
    • Distention/dilation of the renal pelvis and calyces [A] [B].
  • Due to…
    • Usually caused by urinary tract obstruction (e.g., renal stones, BPH, cervical cancer, injury to ureter)
    • Other causes include retroperitoneal fibrosis and vesicoureteral reflux.
  • Findings
    • Dilation occurs proximal to site of pathology.
    • Only impairs renal function if bilateral or patient only has one kidney.
    • Leads to compression atrophy of renal cortex and medulla.
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2
Q

Renal cell carcinoma

  • Definition
  • Due to…
  • Findings
  • Associations
  • Treatment
A
  • Definition
    • Most common 1° renal malignancy
    • Most common in men 50–70 years old
  • Due to…
    • Originates from proximal tubule cells –>Ž polygonal clear cells [A] filled with
      accumulated lipids and carbohydrates.
  • Findings
    • Manifests clinically with hematuria, palpable mass [B] [C], 2° polycythemia, flank pain, fever, and weight loss.
    • Invades renal vein then IVC and spreads hematogenously
      • Metastasizes to lung and bone.
    • “Silent” cancer because commonly presents as a metastatic neoplasm
  • Associations
    • Associated with gene deletion on chromosome 3 (sporadic or inherited as von Hippel-Lindau syndrome).
      • RCC = 3 letters = chromosome 3.
    • Increased incidence with smoking and obesity
    • Associated with paraneoplastic syndromes (ectopic EPO, ACTH, PTHrP).
  • Treatment
    • Resection if localized disease.
    • Immunotherapy or targeted therapy for advanced/metastatic disease.
    • Resistant to chemotherapy and radiation therapy.
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3
Q

Renal oncocytoma

  • Definition
  • Findings
  • Treatment
A
  • Definition
    • Benign epithelial cell tumor (arrows in [A] point to a well-circumscribed mass with a central scar).
  • Findings
    • Large eosinophilic cells with abundant mitochondria without perinuclear clearing [B] (vs. chromophobe renal cell carcinoma).
    • Presents with painless hematuria, flank pain, and abdominal mass.
  • Treatment
    • Nephrectomy.
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4
Q

Wilms tumor (nephroblastoma)

  • Definition
  • Findings
  • Due to…
A
  • Definition
    • Most common renal malignancy of early childhood (ages 2–4).
    • Contains embryonic glomerular structures.
  • Findings
    • Presents with huge, palpable flank mass and/or hematuria.
  • Due to…
    • “Loss of function” mutations of tumor suppressor genes WT1 or WT2 on chromosome 11.
    • May be part of Beckwith-Wiedemann syndrome or WAGR complex:
      • Wilms tumor
      • Aniridia
      • Genitourinary malformation
      • Mental Retardation (intellectual disability).
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5
Q

Transitional cell carcinoma

  • Definition
  • Findings
  • Associations
A
  • Definition
    • Most common tumor of urinary tract system (can occur in renal calyces, renal pelvis, ureters, and bladder) [A].
  • Findings
    • Painless hematuria (no casts) suggests bladder cancer.
  • Associations
    • Associated with problems in your Pee SAC:
    • Phenacetin
    • Smoking
    • Aniline dyes
    • Cyclophosphamide.
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6
Q

Squamous cell carcinoma of the bladder

  • Definition
  • Risk factors
  • Findings
A
  • Definition
    • Chronic irritation of urinary bladder –>Ž squamous metaplasia –>ŽŽ dysplasia and squamous cell carcinoma.
  • Risk factors
    • Schistosoma haematobium infection (Middle East), chronic cystitis, smoking, and chronic nephrolithiasis.
  • Findings
    • Presents with painless hematuria.
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7
Q

Acute infectious cystitis

  • Definition
  • Findings
  • Risk factors
  • Due to…
  • Lab findings
A
  • Definition
    • Inflammation of urinary bladder.
  • Findings
    • Presents as suprapubic pain, dysuria, urinary frequency, and urgency.
    • Systemic signs (e.g., fever, chills) are usually absent.
  • Risk factors
    • Female gender (short urethra), sexual intercourse (“honeymoon cystitis”), and indwelling catheters.
  • Due to…
    • E. coli (most common).
    • Staphylococcus saprophyticus—seen in sexually active young women (E. coli is still more common in this group).
    • Klebsiella.
    • Proteus mirabilis—urine has ammonia scent.
    • Adenovirus—hemorrhagic cystitis.
  • Lab findings
    • Positive for leukocyte esterase (+).
    • Nitrites appear for gram-negative organisms (especially E. coli).
    • Sterile pyuria and (-) urine cultures suggest urethritis by Neisseria gonorrhoeae or Chlamydia trachomatis.
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8
Q

Acute pyelonephritis

  • Findings
  • Due to…
  • Risk factors
  • Complications
  • Treatment
A
  • Findings
    • Affects cortex with relative sparing of glomeruli / vessels [A].
    • Presents with dysuria, fever, costovertebral angle tenderness, nausea, and vomiting.
    • Often presents with white cell casts in urine.
    • CT shows striated parenchymal enhancement (arrow in [B])
  • Due to…
    • Ascending UTI (E. coli is most common), vesicoureteral reflux, and hematogenous spread to kidney.
  • Risk factors
    • Indwelling urinary catheter, urinary tract obstruction, diabetes mellitus, and pregnancy.
  • Complications
    • Chronic pyelonephritis, renal papillary necrosis, and perinephric abscess.
  • Treatment
    • Antibiotics.
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9
Q

Chronic pyelonephritis

  • Definition
  • Due to…
  • Findings
A
  • Definition
    • The result of recurrent episodes of acute pyelonephritis.
  • Due to…
    • Typically requires predisposition to infection such as vesicoureteral reflux or chronically obstructing kidney stones.
  • Findings
    • Coarse, asymmetric corticomedullary scarring, blunted calyx.
    • Tubules can contain eosinophilic casts resembling thyroid tissue [C] (thyroidization of kidney).
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10
Q

Drug-induced interstitial nephritis (tubulointerstitial nephritis)

  • Definition
  • Findings
A
  • Definition
    • Acute interstitial renal inflammation.
  • Findings
    • Pyuria (classically eosinophils) and azotemia occurring after administration of drugs that act as haptens, inducing hypersensitivity.
    • Nephritis typically occurs 1–2 weeks after certain drugs (e.g., diuretics, penicillin derivatives, sulfonamides, rifampin), but can occur months after starting NSAIDs.
    • Associated with fever, rash, hematuria, and costovertebral angle tenderness, but can be asymptomatic.
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11
Q

Diffuse cortical necrosis

  • Definition
  • Due to…
  • Associations
A
  • Definition
    • Acute generalized cortical infarction of both kidneys.
  • Due to…
    • Likely due to a combination of vasospasm and DIC.
  • Associations
    • Associated with obstetric catastrophes (e.g., abruptio placentae) and septic shock.
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12
Q

Acute tubular necrosis

  • Definition
  • Prognosis
  • Key finding
  • 3 stages
  • Due to…
A
  • Definition
    • Most common cause of intrinsic renal failure.
  • Prognosis
    • Self-reversible in some cases, but can be fatal if left untreated.
    • Death most often occurs during initial oliguric phase.
  • Key finding
    • Granular (“muddy brown”) casts [A].
  • 3 stages:
    1. Inciting event
    2. Maintenance phase
      • Oliguric
      • Lasts 1–3 weeks
      • Risk of hyperkalemia, metabolic acidosis
    3. Recovery phase
      • Polyuric
      • BUN and serum creatinine fall
      • Risk of hypokalemia
  • Due to…
    • Ischemic injury
      • 2° to decreased renal blood flow (e.g., hypotension, shock, sepsis, hemorrhage, CHF).
      • Results in death of tubular cells that may slough into tubular lumen [B]
      • Proximal tubule and thick ascending limb are highly susceptible to injury.
    • ƒƒNephrotoxic injury
      • 2° to injury resulting from toxic substances (e.g., aminoglycosides, radiocontrast agents, lead, cisplatin), crush injury (myoglobinuria), hemoglobinuria.
      • Proximal tubule is particularly susceptible to injury.
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13
Q

Renal papillary necrosis

  • Definition
  • Due to…
  • Associations
A
  • Definition
    • Sloughing of renal papillae Ž–> gross hematuria and proteinuria.
  • Due to…
    • May be triggered by a recent infection or immune stimulus.
  • Associated with:
    • ƒƒDiabetes mellitus
    • Acute pyelonephritis
    • Chronic phenacetin use (acetaminophen is phenacetin derivative)
    • Sickle cell anemia and trait
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14
Q

Acute kidney injury (acute renal failure)

  • Normal nephron vs. acute kidney injury
  • Types
A
  • Normal nephron vs. acute kidney injury
    • In normal nephron, BUN is reabsorbed (for countercurrent multiplication), but creatinine is not.
    • Acute kidney injury is defined as an abrupt decline in renal function with increased creatinine and increased BUN over a period of several days.
  • Types
    • Prerenal azotemia
    • Intrinsic renal failure
    • Postrenal azotemia
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15
Q

Prerenal azotemia

  • Type of condition
  • Definition
  • Urine osmolality (mOsm/kg)
  • Urine Na+ (mEq/L)
  • FENa
  • Serum BUN/Cr
A
  • Type of condition
    • Acute kidney injury (acute renal failure)
  • Definition
    • As a result of decreased RBF (e.g., hypotension) Ž–> decreased GFR.
    • Na+/H2O and urea retained by kidney in an attempt to conserve volume, so BUN/creatinine ratio increases.
  • Urine osmolality (mOsm/kg)
    • > 500
  • Urine Na+ (mEq/L)
    • < 20
  • FENa
    • < 1%
  • Serum BUN/Cr
    • > 20
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16
Q

Intrinsic renal failure

  • Type of condition
  • Definition
  • Urine osmolality (mOsm/kg)
  • Urine Na+ (mEq/L)
  • FENa
  • Serum BUN/Cr
A
  • Type of condition
    • Acute kidney injury (acute renal failure)
  • Definition
    • Generally due to acute tubular necrosis or ischemia/toxins
      • Less commonly due to acute glomerulonephritis (e.g., RPGN).
    • Patchy necrosis leads to debris obstructing tubule and fluid backflow across necrotic tubule Ž–> decreased GFR.
    • Urine has epithelial/granular casts.
    • BUN reabsorption is impaired Ž–> decreased BUN/creatinine ratio.
  • Urine osmolality (mOsm/kg)
    • < 350
  • Urine Na+ (mEq/L)
    • > 40
  • FENa
    • > 2%
  • Serum BUN/Cr
    • < 15
17
Q

Postrenal azotemia

  • Type of condition
  • Definition
  • Urine osmolality (mOsm/kg)
  • Urine Na+ (mEq/L)
  • FENa
  • Serum BUN/Cr
A
  • Type of condition
    • Acute kidney injury (acute renal failure)
  • Definition
    • Due to outflow obstruction (stones, BPH, neoplasia, congenital anomalies).
    • Develops only with bilateral obstruction.
  • Urine osmolality (mOsm/kg)
    • < 350
  • Urine Na+ (mEq/L)
    • > 40
  • FENa
    • > 1% (mild)
    • > 2% (severe)
  • Serum BUN/Cr
    • > 15
18
Q

Consequences of renal failure

  • Definition
  • 2 forms of renal failure
  • Consequences
A
  • Definition
    • Inability to make urine and excrete nitrogenous wastes.
  • 2 forms of renal failure
    • Acute (e.g., ATN)
    • Chronic (e.g., hypertension, diabetes, congenital anomalies)
  • Consequences (MAD HUNGER):
    • Metabolic Acidosis
    • ƒƒDyslipidemia (especially increased triglycerides)
    • ƒƒHyperkalemia
    • ƒƒUremia—clinical syndrome marked by increased BUN and increased creatinine
      • ƒƒNausea and anorexia
      • Pericarditis
      • Asterixis
      • Encephalopathy
      • Platelet dysfunction
    • Na+/H2O retention (CHF, pulmonary edema, hypertension)
    • ƒƒGrowth retardation and developmental delay (in children)
    • Erythropoietin failure (anemia)
    • Renal osteodystrophy
19
Q

Renal osteodystrophy

A
  • Failure of vitamin D hydroxylation, hypocalcemia, and hyperphosphatemia Ž–> 2° hyperparathyroidism.
  • Hyperphosphatemia also independently decreases serum Ca2+ by causing tissue calcifications, whereas decreased 1,25-(OH)2 vitamin D –>Ž decreased intestinal Ca2+ absorption.
  • Causes subperiosteal thinning of bones.
20
Q

ADPKD

  • Type of disorder
  • Definition
  • Due to…
  • Findings
A
  • Type of disorder
    • Renal cyst disorder
  • Definition
    • Formerly adult polycystic kidney disease.
    • Innumerable cysts [A] causing bilateral enlarged kidneys (arrows in [B]), ultimately destroy the kidney parenchyma.
  • Due to…
    • Autosomal Dominant
    • Mutation in PKD1 (85% of cases, chromosome 16) or PKD2 (15% of cases, chromosome 4).
  • Findings
    • Presents with flank pain, hematuria, hypertension, urinary infection, progressive renal failure.
    • Death from complications of chronic kidney disease or hypertension (caused by increased renin production).
    • Associated with berry aneurysms, mitral valve prolapse, benign hepatic cysts.
21
Q

ARPKD

  • Type of disorder
  • Definition
  • Due to…
  • Findings
  • Associations
A
  • Type of disorder
    • Renal cyst disorder
  • Definition
    • Formerly infantile polycystic kidney disease.
  • Due to…
    • Autosomal Recessive.
  • Findings
    • Infantile presentation in parenchyma.
    • Significant renal failure in utero can lead to Potter sequence.
  • Associations
    • Associated with congenital hepatic fibrosis.
    • Concerns beyond neonatal period include hypertension, portal hypertension, and progressive renal insufficiency.
22
Q

Medullary cystic disease

  • Type of disorder
  • Definition
  • Findings
A
  • Type of disorder
    • Renal cyst disorder
  • Definition
    • Inherited disease causing tubulointerstitial fibrosis [C] and progressive renal insufficiency with inability to concentrate urine.
  • Findings
    • Medullary cysts usually not visualized
    • Shrunken kidneys on ultrasound.
    • Poor prognosis.
23
Q

Simple vs. complex renal cyst

  • Simple cysts
  • Complex cysts
A
  • Simple cysts
    • Usually found in outer cortex filled with ultrafiltrate [D].
    • Very common, and account for majority of all renal masses.
    • Found incidentally and typically asymptomatic.
  • Complex cysts
    • Including those that are septated, enhanced, or have solid components as seen on CT
    • Require follow-up or removal due to risk of renal cell carcinoma.