Pathology of the Kidneys and UUT

Question 1

Cysts

Answer 1

Simple cysts
Complex cysts
Parapelvic cysts

Use Bosniak grading to determine risk of malignancy

Exact cause unknown
More common as people age
Asymptomatic; rarely cause problems
Do not affect renal function
If large enough, can cause dull pain in flank or back, fever, and upper abdo pain.
Can be solitary or multiple
Can involve one or both kidneys

Ultrasound presentation:
Anechoic, well defined, thin-walled, fluid-filled structure with posterior enhancement

Question 2

Complex cysts

Answer 2

Considered malignant until proven benign

Ultrasound presentation:
May contain septations, thick walls, calcifications, internal echoes, and mural nodularity

Question 3

Parapelvic cysts

Answer 3

Usually ovoid in shape
Originate from the renal sinus
Most likely lymphatic in origin
Do not communicate with the collecting system **
Largely asymptomatic, but may occasionally cause pain, haematuria, hypertension, or obstruction

Question 4

Multicystic Dysplastic Kidney Disease (MCDK)

Answer 4

Abnormal development in utero
Attributed to genetics
Affects one kidney only
Multiple cysts of varying sizes
“Bunch of grapes”
Non-functioning kidney

Question 5

Polycystic Kidney Disease

Answer 5

Can be autosomal dominant (ADPKD) or autosomal recessive (ARPKD)
Both forms can lead to renal failure

Question 6

ADPKD

Answer 6

Twenty times more common
Appears later in life (40+ years)
By age 60 years, approximately 50% of people with ADPKD have end-stage renal disease
Cysts arise from any nephron segment
Bilateral disease
Enlarged kidneys with multiple asymmetrical cysts

Question 7

ARPKD

Answer 7

• Diagnosed in utero or shortly after birth
• Can present with symmetrically enlarged echogenic kidneys that retain their shape
• “Cysts” are dilatations of the collecting duct
• In older children, kidneys are enlarged with echogenic cortex and medulla, and corticomedullary differentiation is lacking

Question 8

Benign solid tumours

Answer 8

Make up about 15-20% of all solid renal tumours in the parenchyma

Four types:
Renal adenomas
Angiomyolipomas
Lipomas
Leiomyomas

Question 9

Renal adenoma

Answer 9

Most common benign renal tumours
Arises from mature tubular cells
Almost always less than 3cm in size
Can’t differentiate them from other solid renal tumours

Types include:
Renal oncocytoma
Papillary adenomas

Ultrasound presentation:
Echogenic or isoechoic well-circumscribed lesion <3cm, but some can be larger

Question 10

Angiomyolipoma

Answer 10

Composed of fat, muscle, and blood vessels
Tumour size varies between 1 and 20 cm
May be multifocal
Incidental finding

Ultrasound presentation:
Well circumscribed echogenic solid lesion (mostly!)

Question 11

Leiomyoma

Answer 11

Rare

Smooth muscle tumour

Question 12

Renal Cell Carcinoma (RCC)

Answer 12

The most common of all renal neoplasms 85 - 95%
Twice as common in men >40yrs
Develops in the sixth or seventh decade of life

Clinical presentation:
Often non-specific
Haematuria, flank pain and palpable mass

Ultrasound presentation:
Most RCC’s are isoechoic, however can be hyperechoic

Question 13

Transitional Cell Carcinoma (TCC)

Answer 13

Rare type of kidney cancer (more in week 8)
Most common bladder and lower UT cancer (ureter, urethra), can arise from the renal pelvis or calyx

Clinical presentation:
Pain in back
Haematuria
Frequent urination

Ultrasound presentation:
Solid hypoechoic lesion/s originating within the renal pelvis or calyx

Question 14

Lymphoma

Answer 14

Renal lymphoma is usually seen as a part of spectrum of multi-systemic lymphoma, however, rarely may be seen as a primary disease

Ultrasound presentation:
Solid hypoechoic lesion/s

Question 15

Wilm’s tumour

Answer 15

Nephroblastoma

Often affects children 3-4 years of age, less common after 5 years of age
The most common cancer in children

Clinical presentation:
Constipation
Abdo pain, swelling, or discomfort
N & V & fever, LOA

Ultrasound presentation:
Large solitary, predominantly solid and echogenic mass
May contain cystic areas – multiloculated mass

Can be present in utero

Question 16

Renal metastases

Answer 16

The most common renal metastases arise from carcinomas, such as lung, colorectal, ENT, breast, soft tissue, and thyroid

Clinical presentation:
Flank pain
Haematuria
Weight loss

Ultrasound presentation :
Variable!

Question 17

Hydronephrosis

Answer 17

Causes:
- Blockage of urine flow down ureter
Internal blockage i.e. calculi, scarring in the ureter, tumour blocking VUJ
External blockage i.e. mass effect compressing ureter closed
- Vesicoureteric reflux (pathology lecture in week 8)

Vesicoureteric reflux:
Failure of the bladder to empty properly
Most common in babies and young children
Can be unilateral or bilateral
Urine refluxes from bladder back up into kidney
Bacteria from bladder can reach the kidney
Can lead to kidney infection and kidney damage

Question 18

Pyelonephritis

Answer 18

Urinary tract infection that starts in urethra or bladder and travels to the kidney/s
Main cause – gram negative bacteria (i.e. E. coli), most often from faeces
P/W fever, nausea, frequent urination, pain in back, side, or groin
Needs medical attention asap – antibiotics +/- hospitalisation

Ultrasound presentation:
Can involve one or both kidneys
Can involve partial or whole kidney/s (focal or diffuse)

Echogenic wedge-defect if partial pyelonephritis
Loss of blood flow seen on colour Doppler

Question 19

Renal abscess

Answer 19

Complication of pyelonephritis
Two types: renal and perirenal

Both start with tubular necrosis
Renal abscesses form a walled-off cavity
Perirenal abscesses appear as a more diffuse liquification area between the renal capsule and fascia

Question 20

Pyonephrosis

Answer 20

Pyo = pus
Pus, debris, or haemorrhage seen within a dilated pelvicalyceal system

Ultrasound presentation:
Echoes seen within the pelvicalyceal system
Can sometimes look solid

Question 21

Glomerulonephritis

Answer 21

Inflammation of the glomeruli
Can be acute or chronic
Usually affects both kidneys
Early diagnosis and treatment needed to prevent renal failure

Causes:
Staphylococcal infection (strep throat)
Immunologic illnesses

Question 22

Renal scarring

Answer 22

Caused by recurrent UTIs – reflux, pyelonephritis
Permanent damage to parenchyma
Reduction in function

Ultrasound presentation:
Appears “on top” of the medullae, not between them
Thinned parenchyma

Question 23

Renal atrophy

Answer 23

• Kidneys are smaller than expected given a person’s age and height
• Can be congenital (renal hypoplasia) or acquired
• Congenital renal atrophy doesn’t treatment; check for normal thickness of parenchyma
• Acquired due to lower blood supply to the kidneys and / or loss of nephrons.
• Can be due to chronic infections or hydronephrosis

Question 24

Renal failure

Answer 24

• End-stage kidney disease
• Kidneys no longer adequately filter the blood of waste products or control level of fluid in the body
• As kidney disease progresses, GFR decreases. By end-stage kidney disease, GFR is less than 15ml per minute
• Can be acute or chronic
• Treatment – dialysis or transplant

Ultrasound presentation:
Acute – may appear normal in size or be enlarged and hypoechoic with parenchymal disease
Chronic – small, echogenic kidneys with loss of normal anatomy

Question 25

Duplex kidney pathology

Answer 25

- Two collecting systems / ureters - Ureters may join before bladder, or result in two ureteric openings - Correct placement for ureter arising from lower pole or moiety - Ectopic placement for ureter from upper pole or moiety - Ectopic ureter more susceptible to reflux as not crossing the bladder wall diagonally as the ureter in the normal place does - Hydronephrosis often present in upper moiety due to reflux - Dysplastic upper moiety (scarring)

Question 26

Urolithiasis

Answer 26

- Commonly known as kidney stones - Similar to gallstones, concentrated urine results in higher amounts of minerals and acid salts that stick together to form the calculi - Most common symptom – severe pain - Can cause obstruction distal to calculi - Treatment – DRINK MORE WATER! May require lithotripsy to break up larger or stuck calculi Ultrasound presentation: Very echogenic with posterior shadowing

Question 27

Medullary Sponge Kidney

Answer 27

Congenital, rare, benign Dilatation of collecting tubules in one or more renal papillae Sponge-like cavitary regions in one or both kidneys Echogenic medullary pyramids May contain nephrocalcinosis

Question 28

Nephrocalcinosis

Answer 28

Calcium levels in the kidneys are increased Causes: Hypercalcaemia due to hyperparathyroidism Some medications Sarcoidosis Tuberculosis of the kidney and AIDS-related infections Vit D toxicity Ultrasound presentation: Calcification in the medullary pyramids Posterior shadowing is dependent on amount of calcification

Question 29

Renal Artery Stenosis

Answer 29

Narrowing of renal artery Leads to renovascular hypertension – a secondary type of blood pressure Causes: RAS at origin – atherosclerosis RAS in distal artery – fibromuscular disease Clinical presentation: Hypertension that cannot be medically-controlled Ultrasound presentation: Stenosis seen on colour Doppler Smaller kidney on side with RAS

Question 30

Renal Infarction

Answer 30

No blood flow to the kidney Thromboemboli or thrombus Can involve the whole kidney or only partial (wedge-defect) Main DDx pyelonephritis and renal tumours Clinical presentation: Pain N / V / Fever Hypertensive

Question 31

Obstructive Nephropathy

Answer 31

Renal changes due to urine blockage Urine backs up into the kidney – becomes swollen Can be uni- or bilateral, depending on where blockage is ``` Common causes: Calculi – bladder or renal Benign prostatic hypertrophy Tumours – primary or secondary Mass-effect lesions blocking ureter/s Scar tissue inside or outside ureter/s or urethra Inability to void ``` Ultrasound presentation: Hydronephrosis (uni- or bilateral) Changes to renal arterial haemodynamics Thinned parenchyma (long-term)

Question 32

Renal Transplantation

Answer 32

- Necessary when the person’s own kidneys no longer filter their blood – end-stage kidney disease - Dialysis artificially cleans the blood several times a week - Transplant can be familiar or a stranger - Donor’s left kidney is used for the transplant (easier access, longer ureter) - Recipient’s kidneys stay in situ usually US request: Depends on how old the transplant is Early days: Size, vascular supply issues / leaks, ureter leaks, hematoma, urinoma, abscess, seroma, lymphocele Later on: Size, vascular supply, resolution of hematoma / urinoma / abscess / seroma / lymphocele

Question 33

Renal Trauma

Answer 33

Can result in: Lacerated kidney Hematoma – perirenal or within kidney Urinoma