Summary of Radiology of Retroperitoneal and Urogenital Pathologies
Radiology of Retroperitoneal & Urogenital Pathologies
Introduction
The kidney is a paired organ responsible for filtering blood, balancing fluids and electrolytes, and eliminating metabolic waste as urine. Understanding common kidney diseases, their clinical signs, ultrasound appearance, and basic management helps in early recognition and appropriate referral.
Definition: The kidney filters blood to produce urine, regulate fluid and electrolyte balance, and maintain acid-base homeostasis.
Acute vs Chronic Renal Failure
Acute Renal Failure (ARF)
- Sudden decrease in renal function; often reversible if recognized and treated.
- Common causes: acute tubular necrosis (ATN) (most common), obstruction, renal artery stenosis, infection.
- Clinical findings: elevated BUN and creatinine, hematuria, oliguria (low urine output), hypertension.
- Ultrasound (US) signs often seen in ATN:
- Enlarged kidneys
- Hyperechoic pyramids which may later return to normal
- Hyperechoic cortex
- Increased resistive index on Doppler
Definition: Acute tubular necrosis (ATN) is damage to renal tubule cells often caused by ischemia or toxins, leading to acute kidney failure.
Chronic Renal Failure (CRF)
- Progressive loss of renal function over time; not usually reversible.
- Causes include chronic glomerulonephritis, hypertensive nephropathy, diabetic nephropathy, chronic pyelonephritis.
- Ultrasound typically shows small, echogenic kidneys with loss of corticomedullary differentiation.
Medullary Diseases (Overview)
Medullary diseases affect the renal medulla and include:
- Medullary sponge kidney
- Renal medullary necrosis (papillary necrosis)
- Medullary nephrocalcinosis
Medullary Sponge Kidney
- AKA tubular ectasia; congenital, often autosomal recessive pattern reported.
- Characterized by cystic dilations of collecting ducts in the medulla leading to urine stasis and stone formation.
- Most common cause of medullary nephrocalcinosis.
- Usually bilateral and appears in younger patients; associated with Caroli disease of the liver.
- Symptoms: often asymptomatic; may present with recurrent nephrolithiasis, hematuria, flank pain, or UTIs.
- Ultrasound: echogenic medullary pyramids when stones are present.
Renal Medullary Necrosis (Papillary Necrosis)
- Papillae of the kidney undergo ischemic necrosis.
- Associated causes: analgesic overuse, ischemia, severe infections, sickle cell disease, diabetes.
- Clinical signs: hematuria, passage of sloughed papillae, decreased urine output (oliguria or anuria).
Medullary Nephrocalcinosis
- Deposition of calcium in the renal medulla.
- Commonly associated with hypercalcemia and hyperparathyroidism.
- Lab: elevated serum calcium.
- US: echogenic calculi in the medulla often with posterior acoustic shadowing.
Renal Masses (Benign and Malignant)
Benign Solid Tumors
- Angiomyolipoma (AML), renal adenoma, hemangioma, oncocytoma, lipoma.
- Angiomyolipoma (AML):
- AKA renal hamartoma; contains fat, vessels, and smooth muscle.
- Common in middle-aged women and in tuberous sclerosis (multiple bilateral AMLs in up to 95% of adult TS patients).
- Usually cortical, hyperechoic and homogeneous on US; may produce speed propagation artifact.
- Large AMLs can cause hematuria or hemorrhage; CT is best modality for fat characterization.
- Oncocytoma:
- Benign tumor of tubular origin, more common in men in their 60s.
- US appearance nonspecific (iso- to hypoechoic); CT may show a central stellate scar.
- Difficult to differentiate from RCC without biopsy or excision.
Malignant Tumors
- Renal cell carcinoma (RCC), Wilms tumor (nephroblastoma, pediatric), transitional cell carcinoma (TCC), metastatic disease, renal lymphoma.
- Renal Cell Carcinoma (RCC):
- Most common primary malignant renal tumor in adults.
- Risk factors: smoking, hypertension, obesity, von Hippel-Lindau
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Kidney Overview
Klíčové pojmy: Acute tubular necrosis (ATN) is the most common cause of acute renal failure and shows enlarged kidneys with hyperechoic pyramids on US., ARF is often reversible; look for elevated BUN/creatinine, oliguria, and increased resistive index on Doppler., Medullary sponge kidney causes cystic dilation of collecting ducts and predisposes to nephrolithiasis., Medullary nephrocalcinosis is calcium deposition in the medulla, commonly from hyperparathyroidism and hypercalcemia., Angiomyolipoma is a benign hyperechoic cortical mass often associated with tuberous sclerosis and may contain fat detectable on CT., Renal cell carcinoma typically appears as an iso- to hypoechoic hypervascular solid mass and can invade the renal vein/IVC., ADPKD causes bilateral enlarged kidneys with multiple cysts, early hypertension, and increased risk of RCC and cerebral aneurysms., Multicystic dysplastic kidney is usually unilateral in infants with noncommunicating cysts and contralateral compensatory hypertrophy., Acquired cystic disease of dialysis appears after years on dialysis and increases RCC risk., Simple renal cysts are anechoic with thin walls and posterior enhancement and generally require no treatment.