Pathology of the Kidneys and UUT Part 1 Flashcards

Cysts

Types of Cysts

• Simple Cysts: Anechoic, imperceptible wall, round shape. No workup required, approximately 0% chance of malignancy.

• Complex Cysts: Considered malignant until proven benign. Can have multiple internal features (septations, nodularity, etc.).

• Parapelvic Cysts: Typically ovoid, originate from renal hilum; asymptomatic but may cause pain or obstruction.

Bosniak Classification of Renal Cysts: grading to determine risk of malignancy

Detailed Characteristics

Simple Cysts

• Aetiology: Unknown, more common as people age

• Presentation: Asymptomatic; occasionally causes flank or abdominal pain when large, do not affect renal function.

• Sonographic Appearance: Anaechoic, well-defined, fluid-filled structure, with posterior enhancement.

Complex Cysts

• Presentation: May have septations, thick walls, and calcifications.

• US Presentation: Internal echoes and mural nodularity are common

Parapelvic Cysts

• Characteristics: Ovoid, originate from within the renal hilium, close to the renal pelvis and calcyes NOT within the renal parenchyma, lymphatic origin, does not communicate with the collecting system.

• Clinical Consequence: Usually asymptomatic but can cause pain, haematuria, obstruction or hypertension.

• SEPARATE CYSTIC STRUCTURES

Multicystic Dysplastic Kidney Disease (MCDK)

• Definition: Abnormal development in utero, often genetic; affects one kidney.

• Presentation: Multiple cysts of various sizes; described as resembling a "bunch of grapes."

• Non-functioning kidney

Polycystic Kidney Disease (PKD)

Types

• Autosomal Dominant (ADPKD): More common; displayed later in life (age 40+). 50% progression to end-stage renal disease by age 60.

  • Presentation: Bilateral disease with multiple asymmetrical cysts leading to enlarged kidneys.

• Autosomal Recessive (ARPKD): Diagnosed at birth or utero; bilateral enlargement with echogenic kidneys retaining shape; collecting duct dilatations.

• In older children, kidneys are enlarged with echogenic cortex and medulla and corticomedullary differentiation is lacking

Renal Benign Solid Tumours

• Overview: Constitute about 15-20% of all solid renal tumours.

Types

1. Renal Adenomas: Most common benign tumours; arising from mature tubular cells, typically <3cm.

   • Subtypes: Renal oncocytoma, papillary adenomas.

   • US Appearance: Echogenic or isoechoic, well-circumscribed lesions and can be >4cm

2. Angiomyolipomas: Tumours composed of fat, muscle, and blood vessels; size varies (1-20cm).

   • US Appearance: Well-defined, echogenic solid lesions, often asymptomatic; no colour flow

3. Lipomas: Rare; composed of adipose tissue.

4. Leiomyomas: Rare smooth muscle tumours; echogenicity can vary.

Summary

• Review key sonographic terminology related to renal pathologies.

• List differential diagnoses for hypoechoic and hyperechoic lesions in the kidney.

• Describe sonographic features of various cyst classifications and their malignancy risks.