Pediatric Renal Abscess

  • Etiology:
    — Infected fluid collection that is uncommon complication of acute pyelonephritis
    — May be associated with renal stones and obstructive uropathy
  • Imaging US: Well-defined hypoechoic lesion within cortical or cortical medullary parenchyma
  • Imaging US Color Doppler: Decreased vascularity and blood flow
  • Imaging CT: Well-defined low density lesion with thick irregular wall in kidney with obscuration of perinephric fat
  • DDX: Complicated renal cyst, renal tumor
  • Complications: Abscess rupture into calyceal system or perinephric space or anterior or posterior pararenal space or peritoneal cavity
  • Treatment: Antibiotics
  • Note: Must document resolution of abscess at end of therapy in order to rule out underlying renal tumor
  • Clinical: Present with fever and flank pain or abdominal pain and chills and dysuria

Radiology Cases of Renal Abscess

CT and US of renal abscess
Axial (left upper) and coronal (right upper) CT with contrast of the abdomen shows a round low density lesion in the lower pole of the left kidney. Transverse (lower left) and sagittal (lower right) color doppler US of the the left kidney shows the round lesion in the lower pole to be solid and avascular in nature.
CT of pediatric acute pyelonephritis followed by development of a renal abscess
Coronal CT without contrast of the abdomen (above) shows an enlarged left kidney with associated perinephric fat around its inferior pole. Sagittal (below left) and transverse (below left) ultrasound of the left kidney obtained 1 month later after antibiotic treatment shows a well-circumscribed, round, isoechoic lesion in the inferior pole of the left kidney.

Radiology Cases of Renal Abscess Due to Infective Endocarditis

MRI of infective endocarditis of the brain and CT of infective endocarditis of the spleen and kidneys
Coronal T1 MRI with contrast of the brain (above) shows multiple small enhancing lesions in the brain and one large ring enhancing lesion in the right hemisphere of the brain. Coronal CT with contrast of the abdomen (below) shows multiple peripheral low density wedge shaped lesions in the spleen and both kidneys.