FA - Renal Pathology Flashcards
What are causes of RBC casts?
Glomerulonephritis, ischemia, or malignant HTN
What are causes of WBC casts?
Tubulointerstitial inflammation, acute pyelonephritis, transplant rejection
What are causes of fatty/oval body casts?
Nephrotic syndrome
What are causes of granular/muddy brown casts?
ATN
What are causes of waxy casts?
Advanced renal disease/chronic renal failure
What are causes of hyaline casts?
Non-specific and can be a normal finding
What defines a focal glomerular disorder and what is an example?
<50% of glomeruli involved, e.g. FSGS
What defines a diffuse glomerular disorder and what is an example?
> 50% of glomeruli involved, e.g. DPGN
What defines a proliferative glomerular disorder and what is an example?
Hypercellular glomeruli, e.g. mesangial proliferative
What defines a membranous glomerular disorder and what is an example?
Thickening of GBM, e.g. membranous nephropathy
What defines a primary glomerular disease and what is an example?
Involves only the glomerulus, e.g. minimal change dz
What defines a secondary glomerular disease and what is an example?
Involves glomeruli and other organs, thus a dz of another organ system or a systemic dz with renal manifestation, e.g. SLE, diabetic nephropathy
What are some pure nephritic syndromes?
Acute PSGN, RPGN, Berger’s IgA GN, Alport syndrome
What are some pure nephrotic syndromes?
Minimal change dz, FSGS, membranous nephropathy, amyloidosis, diabetic glomerulonephropathy
What are some mixed nephritic/nephrotic syndromes?
DPGN, MPGN
What are general features of nephrotic syndrome?
Proteinuria (frothy urine), hyperlipidemia, fatty casts, edema.
May also see thromboembolism (loss of AT III) and increased risk of infection (loss of Igs)
What are the findings in FSGS?
LM - segmental sclerosis and hyalinosis
EM - effacement of podocyte foot processes
What are common associations in FSGS?
Most common cause of nephrotic syndrome in adults (esp. AA, Hisp. populations)
Assoc. with HIV infection, heroin abuse, massive obesity, interferon treatment, CKD due to congenital absence or surgical removal
What are the findings in membranous nephropathy?
LM - diffuse capillary and GBM thickening
EM - “spike and dome” appearance with SUBEPITHELIAL deposits
IF - granular
What are common associations in membranous nephropathy?
Most common SLE presentation
Second most common cause of primary nephrotic syndrome in adults (esp. Caucasians)
Can be idiopathic or caused by drugs, infections, SLE, solid tumors
What are the findings in minimal change disease?
LM - normal glomeruli
EM - diffuse effacement of podocyte foot processes
Selective loss of albumins due to GBM polyanion loss
What are the common associations in minimal change disease?
Most common in children. May be triggered by a recent infection or an immune stimulus. Responds to corticosteroid Rx
What are the findings in amyloidosis?
Congo red stain shows apple-green birefringence under polarized light
What are the associations in amyloidosis?
Chronic conditions such as multiple myeloma, TB, RA
What are the findings in Type I MPGN?
EM - subendothelial “tram track” deposits (GBM splitting due to mesangial ingrowth)
IF - granular staining
What are the findings in Type II MPGN?
EM - intramembranous IC deposits (dense deposits)
What are the associations in Type I MPGN?
Associated with HBV, HCV
What are the associations in Type II MPGN?
Associated with C3 nephritic factor
What are the findings in diabetic glomerulonephropathy?
LM - nonenzymatic glycosylation of GBM –>inc. permeability and thickening, mesangial expansion, K-W lesions
What are the associations in diabetic glomerulonephropathy?
NEG of efferent arterioles –>increased GFR and mesangial expansion
What are general features of nephritic syndrome?
Inflammatory process which leads to hematuria and RBC casts in urine. Associated with azotemia, oliguria, hypertension (secondary to salt retention), proteinuria (<3.5g/day)
What are the findings in acute PSGN?
LM - glomeruli enlarged and hypercellular, neutrophils, “lumpy-bumpy” appearance
EM - subepithelial immune complex humps
What are the associations in PSGN?
Most frequently seen in children
Peripheral and periorbital edema, dark urine, hypertension
Resolves spontaneously
What are the findings in RPGN?
LM and IF - crescent moon shaped
Crescents consist of fibrin and plasma proteins (e.g. C3b) with glomerular parietal cells, monocytes, and macrophages
What disease processes can present like RPGN?
Goodpasture's syndrome -- type II HSR, antibodies to GBM and alveolar BM with linear IF Wegener's granulomatosis (c-ANCA) Microscopic polyangiitis (p-ANCA)
What are the findings in DPGN?
LM - wire looping of capillaries
EM - subendothelial and sometimes intramembranous IgG-based ICs often with C3 deposition
IF - granular
What are the associations in DPGN?
Most common cause of death in SLE
SLE and MPGN can present as nephrotic syndrome and nephritic syndrome concurrently
What are the findings in IgA nephropathy?
LM - mesangial proliferation
EM - mesangial IC deposits
IF - IgA based IC deposits in the mesangium
What are the associations in IgA nephropathy?
Associated with HSP (fever, petechial rash, arthalgia, GI disturbance), may follow recent illness (URI, gastroenteritis)
What features define Alport syndrome?
X-linked mutation in Type IV collagen –>split BM
Presents as glomerulonephritis, deafness, eye problems (less common)
What are the general complications of kidney stones and how can they be prevented?
Can lead to severe complications, such as hydronephrosis and pyelonephritis
Treat and prevent by adequate hydration, citrate (Ca++ binder) for recurrent stones
What are the most common types of kidney stones and how do they precipitate?
Calcium (80%, radioopaque), precipitates as calcium phosphate at high pH, calcium oxalate at low pH (hypercalciuria + normocalcemia)
What are some conditions that predispose to calcium stones?
Conditions that cause hypercalcemia (cancer, high PTH) –>hypercalciuria
What are some conditions that predispose to calcium oxalate conditions?
Ethylene glycol use or Vitamin C abuse
What are the features of ammonium magnesium phosphate (struvite) stones?
15% of stones, radioopaque, precipitate at high pH
Caused by infection with urease+ bugs (Proteus, Staphylococcus, Klebsiella) that hydrolyze urea to ammonia –>increased urine pH
Can form staghorn calculi –>nidus for UTI
What are the features of uric acid stones?
5% of stones, radiolucent (visible on CT/US but not X-ray), precipitate at low pH
Strong association with hyperuricemia; often seen in diseases with high cell turnover. Treat by urine alkalinization.
What are the features of cystine stones?
1% of stones, radioopaque, precipitate at low pH.
Most often secondary to cystinuria, hexagonal crystal. Treat by urine alkalinization.
What are the causes of hydronephrosis?
Can be caused by urinary tract obstruction or vesicoureteral reflux
What are the consequences of hydronephrosis?
Causes dilation of the renal pelvis and calyces proximal to obstruction. May result in parenchymal thinning in chronic, severe cases.
What are the features of renal cell carcinoma?
Originates from proximal tubular cells –>polygonal clear cells filled with accumulated lipids and carbohydrates
What is the classic triad of RCC? What are other clinical findings?
Triad: hematuria, palpable mass, flank pain; may also see secondary polycythemia, fever, and weight loss
What are common sites of metastasis in RCC?
Lung and bone
What is the epidemiology of RCC? What is the genetic defect?
Males 50-70 years, increased incidence with smoking and obesity. Sporadic gene deletion on chromosome 3 or inherited (VHL syndrome). May also be associated with paraneoplastic syndromes.
What are the features of Wilms’ tumor?
Contains embryonic glomerular structures. Presents with huge, palpable flank mass and/or hematuria.
What is the epidemiology of Wilms’ tumor?
Most common renal malignancy of early childhood (ages 2-4)
Caused by deletion of tumor suppressor gene WT1 on chromosome 11.
May be part of Beckwith-Wiedemann syndrome (WT2) or WAGR complex (Wilms’ tumor, aniridia, genitourinary malformation, mental retardation)
What are the features of transitional cell carcinoma?
Most common tumor of the urinary tract (renal calyces, renal pelvis, ureters, bladder). Presents with painless hematuria.
What are the features of acute pyelonephritis?
Affects the cortex with relative sparing of glomeruli/vessels. Presents with fever, CVA tenderness, n/v.
WBC casts in urine are classic.
What are the histological findings in acute pyelonephritis?
Neutrophilic infiltration into renal interstitium.
What are the causes/predisposing factors of chronic pyelonephritis?
Result of recurrent episodes of acute pyelonephritis. Typically requires predisposition to infection such as vesicoureteral reflux or chronically obstructing kidney stones
What are the histologic findings in chronic pyelonephritis?
Coarse, asymmetric corticomedullary scarring with lymphocytic infiltration and fibrosis, blunted calyx, tubules can contain eosinophilic casts (thyroidization)
What are the features of drug-induced interstitial nephritis?
Acute interstitial renal inflammation. Pyuria (eosinophils) and azotemia occurring after administration of drugs that act as haptens, including HSR –>fever, rash, hematuria, CVA tenderness OR asymptomatic
What are the types of drugs implicated in interstitial nephritis?
Typically occurs 1-2 weeks after use of diuretics, penicillin derivatives, sulfonamides, rifampin or months after starting NSAIDs
What are the features of diffuse cortical necrosis?
Acute generalized cortical infarction of both kidney. Likely due to combination of vasospasm and DIC
What is the epidemiology of diffuse cortical necrosis?
Associated with obstetric catastrophes (e.g. abruptio placentae) and septic shock
What are the features of acute tubular necrosis?
Most common cause of intrinsic renal failure.
3 stages: Inciting event, maintenance phase (oliguria, lasts 1-3 weeks with risk of hyperkalemia, highest risk of death), recovery phase (polyuric, BUN/Cr fall, risk of hypokalemia). Hallmark muddy brown casts.
What are possible causes of ATN?
Renal ischemia (shock, sepsis), crush injury (myoglobinuria), drugs (sulfonamides, MTX, IV acyclovir, triamterene), toxins
What are the features of renal papillary necrosis?
Sloughing of renal papillae –>gross hematuria and proteinuria. May be triggered by recent infection or immune stimulus.
What are common associations in renal papillary necrosis?
Diabetes mellitus, acute pyelonephritis, chronic phenacetin use, sickle cell anemia and trait
What is the definition of ARF/AKI?
Acute renal failure is defined as an abrupt decline in renal function with increased Cr and BUN over a period of several days
What defines prerenal azotemia?
As a result of decreased RBF –>decreased GFR. Na+/H2O and urea retained by kidney in an attempt to conserve volume so BUN/Cr ratio increases
What defines intrinsic renal failure?
Generally due to ATN or ischemia/toxins; less commonly due to acute glomerulonephritis.
Patchy necrosis leads to debris obstructing tubule and fluid backflow across necrotic tubule –>dec. GFR
Impaired BUN reabsorption –>decreased BUN/Cr ratio
What defines postrenal azotemia?
Due to outflow obstruction (stones, BPH, neoplasia, congenital anomalies). Develops only with bilateral obstruction
What is the Uosm, UNa, FeNa, and serum BUN:Cr in prerenal azotemia?
Uosm >500, UNa 20
What is the Uosm, UNa, FeNa, and serum BUN:Cr in intrinsic renal failure?
Uosm 40, FeNa >2%, serum BUN:Cr <15
What is the Uosm, UNa, FeNa, and serum BUN:Cr in postrenal azotemia?
Uosm 40, FeNa >2%, serum BUN:Cr >15
What are some cardiovascular consequences of renal failure?
Na+/H2O retention –>CHF, pulmonary edema, HTN
What are some metabolic consequences of renal failure?
Hyperkalemia, metabolic acidosis, dyslipidemia, uremia (elevated BUN:Cr, nausea and anorexia, asterixis, encephalopathy, platelet dysfunction)
What are some hematological consequences of renal failure?
Anemia (failure of Epo production)
What are some pediatric complications of renal failure?
Growth retardation and developmental delay
What are some renal complications of renal failure?
Renal osteodystrophy –>failure of Vit D hydroxylation, hypocalcemia, hyperphosphatemia (secondary hyperparathyroidism) –>subperiosteal thinning of bones
What defines ADPKD?
Multiple, large, bilateral cysts that ultimately destroy the kidney parenchyma. Presents with flank pain, hematuria, HTN, UTI, progressive renal failure. Malignant potential.
What is the epidemiology of ADPKD?
AD mutation in PKD1 or PKD2. Death from complications of CKD or HTN (caused by increased renin production). Syndrome presents in middle age.
What are common associations of ADPKD?
Berry aneurysms, MVP, benign hepatic cysts
What defines ARPKD?
Infantile, parenchymal presentation (radial formation). Significant renal failure in utero can lead to Potter’s syndrome. Concerns beyond neonatal period include HTN, portal HTN, progressive renal insufficiency
What defines medullary cystic disease (cystic renal dysplasia)?
Inherited disease causing tubulointerstitial fibrosis and progressive renal insufficiency with inability to concentrate urine. Medullary cysts usually not visualized; shrunken kidneys on ultrasound. Poor prognosis.
