kidney pathlo

uCystic Renal Masses—Cortical Cysts

uCommon Renal masses-benign in nature

uHave epithelial lining with simple serous fluid

uVary in size from 1 mm to giant cysts containing 5,000 mL of clear amber fluid.

uUsually unilocular but may contain some septations or loculations.

uCan be located anywhere in the kidney, including adjacent tissues of the renal pelvis (peripelvic cyst) and small divisions of collecting system.

uUltrasound determines the location of the cyst.

uSimple Renal Cyst

uOccur in 50% of people over the age of 50

uMost renal cysts are simple cortical cysts that originate from obstructed uriniferous tubules (functional kidney tubules)

uTypes of renal cyst include:

uPyelogenic

uCalyceal diverticula that sonographically appear as a simple cyst

uParapelvic

uCortical cysts that bulge into the central sinus of the kidney

uPeripelvic

uLymphatic cysts in the central sinus

uSimple Renal Cyst

Sonographic Findings

uAcoustic enhancement

uAbsence of internal echoes

uSharply defined thin wall

uRound or oval in shape

uCortical or parenchymal cysts are located in the periphery

uPeripelvic cysts are located in the center (renal sinus) of the kidney

uComplex Cysts—Hemorrhagic Cysts

u≈6% of simple renal cysts show hemorrhage and the prevalence of hemorrhage increases in polycystic kidney disease.

uReported incidence of neoplasm in these lesions approaches 30%.

uLesions not meeting classical criteria for a cyst should be investigated by aspiration or CT.

uPresence of blood on CT in any form increases attenuation—hemorrhagic cysts appear hyperdense

uAtypical Renal Cysts

uCysts with a single thin septation, minimal wall calcification, internal echoes caused by artifact or lobulated shapes may all be associated with simple benign cysts

uCharacteristics that are atypical and may suggest a malignant cystic lesion include:

uMultiple thick septation

uIrregular walls

uSolid component

uThese cysts should require histological confirmation (fine needle aspiration) for definitive diagnosis.

uCalcifications in Cysts

uLayered, eggshell-thin cyst wall is hyperechoic, decreasing sound transmission and makes accurate diagnosis difficult.

uIncreased association with malignancy

uImportant to obtain images from two scanning planes, as cyst pattern can be identified in calcium-free portions.

uMilk of Calcium (MOC)

urepresents small calcium carbonate crystals but can form from other substances.

uMOC may move within the cystic mass when patient changes position

uMOC is usually asymptomatic and requires no treatment.

uTuberous Sclerosis

uA multi-system genetic disease. Classic presentation includes: seizures, mental retardation, and facial angiofibromas.

uThe kidneys are the main focus of a abdominal sonographic evaluation in a patient with tuberous sclerosis.

uPatients with tuberous sclerosis have an increased incidence of renal cysts and angiomyolipomas.

uAngiomyolipomas are typically bilateral in patients with tuberous sclerosis.

uVon Hippel-Lindau Disease

uAutosomal Dominant disorder.

uVon Hippel Lindau syndrome is characterized by retinal and central nervous system hemangioblastoma

uPresents in the 3rd -5th decade of life.

uTumors are bilateral in up to 75% of cases and multifocal in 80% to 90% of cases.

uConcurrent Findings:

uRenal cell carcinomas ( Kidneys)

uPheochromocytomas ( Adrenal)

uIslet cell tumors ( Pancreas)

uRenal and pancreatic cysts

uAngiomyolipoma

uHyperechoic benign renal tumor with echogenicity is greater than or equal to that of the renal sinus.

uA propagation speed artifact may result in the posterior displacement of structures due to slower acoustic velocity in this fatty mass.

uCT confirmation of fat in an echogenic renal mass is considered diagnostic of angiomyolipoma.

u80% Involve the right kidney

uMalignant Neoplasms–Renal Cell Carcinoma

uAKA: hypernephroma or adenocarcinoma

uMost common malignant tumor of kidney ≈ 80% to 90% of all renal malignancies in adults.

uOccurs most often after age 50 and has a 2:1 male to female ratio.

u10% to 25% incidence of bilateral or multifocal RCC in patients with von Hippel-Lindau disease

uClassic symptoms include costovertebral angle pain, a palpable mass, and hematuria but only 15% of patients present with all three symptoms

uNephrectomy is recommended

uTumor extension into the renal veins and inferior vena cava is common.

uThe lungs are the most common site of distant metastases. Lymph nodes, liver, bone, adrenal glands, and the contralateral kidney are also metastatic sites.

uRCC Sonographic Findings

uHypoechoic relative to the normal adjacent renal parenchyma

uRCC with IVC invasion

uRenal Metastases

uRenal parenchyma may be the site of secondary tumors that have metastasized from other primary organs (lung, breast, colon, etc...)

uMalignant cells from leukemia and lymphoma can metastasize to the kidney.

uSonographically presents as:

uHypoechoic masses

uDiffusely enlarged inhomogeneous kidney

uWilm’s Tumor

uWilm's tumor (nephroblastoma) is the most common childhood renal tumor

uMean age at diagnosis is 3-4years

uPatients typically present with a large asymptomatic flank mass. Other symptoms include:

uhypertension

ufever

uHematuria

uMetastasis can be seen to the lungs, liver, bone, lymph nodes, and retroperitoneum.

u90% survival rate

uTumor extension can be seen into the renal vein and inferior vena cava

uWilm's tumors must be differentiated from adrenal neuroblastomas. Wilm's tumors destroy the renal contour. If normal renal contour is maintained bilaterally, an abdominal mass is most likely an adrenal neuroblastoma.

uHydronephrosis

uDilatation of the renal pelvis and calyces.

uThe normal renal sinus is a central echogenic area composed of peripelvic fat, renal vessels, lymph nodes and collecting structures.

uProduces a separation of the normal sinus echogenicity by an anechoic urine collection.

uOccurs in 65% to 85% of pregnancies ( Rt)

uIf untreated, hydronephrosis secondary to obstruction can lead to:

uHypertension

uLoss of renal function

uSepsis

uHydronephrosis

uCommon causes include:

uCalculi

uBenign prostatic hypertrophy

uProstate cancer

uPelvic malignancies

uPregnancy

uUreteropelvic junction obstruction

uThree common areas of obstruction by a stone:

uUreterovesical junction (most common)

uUreteropelvic junction

uPelvic brim

uObstructive nephropathy is also diagnosed by evaluating the intrarenal vascularity.

uAn RI difference between the kidneys of greater than 0.1 has been shown to be indicative of functionally significant unilateral obstruction.

uHydronephrosis

uGrade I Hydronephrosis

uGrade II Hydronephrosis

uHydronephrosis

uGrade III Hydronephrosis

uUrolithiasis (arrows) is noted within the proximal ureter in both images

uNephrolithiasis

uCalculi can develop anywhere in the urinary system (urolithiasis)

uMost develop in the kidney (nephrolithiasis)

uPrevalence of nephrolithiasis is 0.1% to 5% of population in industrial countries

uMore common in White men aged 20 to 50 years

u> 80% of nephrolithiases contain some form of calcium

uUreteral stones are more difficult to visualize with sonography and may only be detected if ureter is significantly dilated

uNephrolithiasis

uKidney Stones

Bladder Jets

uNephrocalcinosis

uNephrocalcinosis is renal parenchymal calcium deposition, predominantly cortical or medullary or involving both regions

uNephrolithiasis occurs in the collecting system

uCortical nephrocalcinosis is usually bilateral and diffuse

uSonography appearance of nephrocalcinosis may be difficult to differentiate from large renal calculi (staghorn calculi) or air (emphysematous pyelonephritis)

uCauses of Nephrocalcinosis

uMedullary nephrocalcinosis (95%)

uHyperparathyroidism

uRenal tubular acidosis type I

uMedullary sponge kidney

uCortical nephrocalcinosis (5%)

uChronic glomerulonephritis

uRenal cortical necrosis

uTransplant kidney: Chronic rejection

uMedullary Sponge Kidney

A. Note the tiny bright dots in the pyramids, represents small calculi

B. Same patient, linear array transducer angled medially to demonstrate the small calculi

uAcute Pyelonephritis

uMost renal infections occur via an ascending route from the bladder.

uEither unilateral or bilateral

uOnset is usually abrupt

uAPN most common in women aged 15 to 35 years and occurs in 1% to 2% of all pregnant women

uClose correlation of patient’s clinical course is vital

u- Ultrasound findings include:

uUnilateral or bilateral;

uFocal (multifocal) or diffuse;

uFocal swelling or no focal swelling; and

uRenal enlargement or no renal enlargement

uAbsence of sinus echoes

uUltrasound may be normal

uAcute Pyelonephritis

uThis is a tubulointerstitial inflammation of the kidney

uBoth the renal pelvis and parenchyma are inflamed

uBacteria enters bladder and ascends the ureter, enters the renal tubules at the papillary tip, via the collecting system

uE. Coli is a big offender

uMay lead to perinephric abscess

uTreatment is antibiotics, both oral and IV

uUltrasound is useful in identifying renal and perirenal abscesses, stones, and hydronephrosis

uEmphysematous Pyelonephritis

uLife-threatening disease with mortality rate as high as 30% to 40%

uEmphysematous pyelonephritis is a bacterial infection associated with renal ischemia.

uMore commonly occurring in diabetics (87-97% of patients), immunosuppressed patients and patients with urinary tract obstructions.

uMost commonly caused by E. coli infection

uNephrectomy is usually required to treat infection.

uChronic Pyelonephritis

uRenal injury induced by recurrent renal infection due to pathologic involvement of calyces and pelvis.

uRecurrent renal inflammatory bouts eventually scar kidney and obstructions contribute to parenchymal atrophy

uSevere hypertension contributes to disease progressing

uSignificant cause of renal failure—responsible for 25% of renal insufficiency cases and end-stage renal disease

uSonographically, chronic pyelonephritis leading to end-stage renal disease, appears as a small hyperechoic kidney with cortical thinning.

uXanthogranulomatous Pyelonephritis (XGPN)

uRare type of CPN resulting from chronic infections due to a long term obstruction.

uCharacterized by replacement of normal renal parenchyma with lipid-laden (foamy) macrophages, plasma cells, and multinucleated giant cells

uMost common predisposing factors are chronic infection and obstruction of the ureteropelvic junction, generally from a staghorn calculus

uWomen and diabetic patients seem more susceptible.

uFailure to depict a normal kidney associated with a staghorn calculus suggest the diagnosis of XGPN

uPatients normally present with this triad:

u75% have renal calculi, usually of the staghorn variety;

uhave renal enlargement; and

ulack of renal function.

uPyonephrosis

uAKA: Pyohydronephrosis

uPurulent material in the collection system of the kidney associated with an infection secondary to renal obstruction.

uPercutaneous or surgical drainage is required for adequate treatment.

uSonography findings are variable owing to stage and duration of inflammation and extent of proteolysis of purulent material

uFungal Infections

uCandidiasis is the most common renal fungal disease.

uFungal infections result from hematogenus seeding or ascend from the bladder.

uSonographic Findings: hyperechoic, nonshadowing masses.

uAt risk: Premature infants with long-term indwelling catheters for prolonged hyperalimentation and adult patients with diabetes, cancer (especially leukemia or lymphoma); indwelling foreign bodies; chronic illness; intravenous drug abuse; prolonged antibiotic, corticosteroid or immunosuppressive therapy; and immunocompromise from AIDS

uAcute Renal Failure (ARF)

uAn abrupt decrease in renal filtration marked by an increase in serum creatinine or blood urea nitrogen (azotemia). However, immediately after kidney injury the only sign of ARF may be a decrease in urine production.

uThree main mechanisms of ARF:

uPrerenal Failure

uHypotension

uVolume depletion

uDecreased Cardiac Output

uIntrinsic (Intrarenal) Renal Failure

uAcute tubular necrosis (most common)

uGlomerular diseases (Nephritic syndrome)

uInterstitial nephritis (Drugs or Contrast agents)

uAutoimmune diseases

uPostrenal Failure

uBilateral renal obstruction

uAcute Renal Failure (ARF)

uUltrasound's role in diagnosing the cause of acute renal failure is to determine:

uHydronephrosis (indicates postrenal failure)

uAbnormal resistive index (suggests intrinsic)

uDistinguishing the cause is important in relieving obstruction and in facilitating appropriate treatment of other renal medical disease.

uPrompt intervention prevents loss of renal parenchyma.

uLaboratory studies used to evaluate ARF:

uUrine output

uUrinalysis

uBlood urea nitrogen

uSerum creatinine

uChanges in serum creatinine reflecting changes in glomerular filtration rate, is the most accurate method of determining ARF.

uAcute Tubular Necrosis

uATN is the most common cause of medical renal disease or intrinsic (Intrarenal) acute renal failure.

uATN results from prolonged ischemia or nephrotoxins (drugs and contrast agents) causing damage to the tubular epithelium of the nephron leading to acute renal failure.

uThe renal insufficiency that occurs in ATN can be reversible.

uMore likely occurs in patients with history of recent surgery, sepsis, or hypovolemia.

uSonographic findings include:

uRenal enlargement

uIncreased resistive index (RI)

uAcute Glomerulonephritis

uAcute glomerulonephritis is an inflammatory response resulting in glomerular damage caused by infectious and noninfectious causes.

uThe most common infectious cause of acute GN is infection by Streptococcus species due to upper respiratory and skin infections.

uPresenting symptoms include:

uSudden onset of hematuria

uProteinuria

uAzotemia

uRed blood cell casts in urine

uSonographic findings

uRenal enlargement

uIncreased resistive index (RI)

uRenal Sinus Lipomatosis

uIncreased renal sinus fat that replaces normal renal parenchyma.

uUltrasound shows an increase in the central sinus echo complex with cortical thinning.

uIntravenous urography demonstrates compression of the calyces and renal pelvis by renal sinus fat.

uPapillary Necrosis

uIschemia of the medullary pyramids.

uClinical diagnosis can be made by identifying sloughed papilla in the urine. Passage of sloughed papillae can cause pain and ureteric obstruction.

uPapillary necrosis is associated with the following conditions:

uAnalgesic abuse (most common)

uDiabetes mellitus

uUrinary tract obstruction and infections

uRenal vein thrombosis

uSickle cell disease

uChronic heart failure

uPapillary Necrosis Sonographic Findings

uEchogenic material within the collecting system representing sloughed papillae.

uTriangular cystic collections are seen representing the absence of the medullary pyramids.

uBright echoes produced by the arcuate arteries can be visualized at the periphery of the cystic space.

uRenal Vein Thrombosis

uAssociated with:

uExtrinsic compression

uNephrotic syndrome (most common)

uRenal tumors

uRenal transplants

uTrauma

uUrinary retention / low urine output

uSonographic findings include:

uDilated thrombosed renal vein

uAbsent intrarenal venous flow

uEnlarged hypoechoic kidney

uHigh-resistance renal artery waveform

u(Increased RI)

uRenal Artery Thrombosis

uRenal artery thrombosis (occlusion) is a sudden cause of prerenal failure that presents as:

uAcute flank pain

uHematuria

uSudden rise is blood pressure

uSonographic findings include:

uFocal hypoechoic areas of infarct

uAbsence of intrarenal arterial flow

uRenal enlargement

uChronic Kidney Disease

uAn irreversible disease that affects the function of the nephrons, causing a decreased GFR, tubular function, and reabsorption.

uTwo main causes of CKS are diabetes, HTN

uOther causes : glomerulonephritis, chronic pyelonephritis, renal vascular disease

uSonographic findings

uEchogenic kidneys

uDiminished kidney size, < 9cm

uCortical thinning

uPoor visualization of renal sinus and pyramid

Cortical thickness may be more sensitive than renal length in determining the progression of disease and should be used for follow up care.

uChronic Kidney Disease

uA. A patient with CKD with small echogenic kidneys

uB An obese patient with a large layer of perinephric fat presented with CKD related to diabetes.