Diagnostic Ultrasound - Abdomen and Pelvis

Renal Junction Line
Diagnoses: Urinary Tract
TERMINOLOGY
• Defect or line representing incomplete embryologic fusion
of 2 primary renal lobes: Upper and lower poles of kidney
IMAGING
• Wedge-shaped hyperechoic defect or echogenic line at
upper to middle 1/3 of kidney
• No associated loss of parenchyma
• Characteristic location at anterosuperior aspect of kidney
• More commonly seen on right
• Variable size of defect
• Overlays column of Bertin
TOP DIFFERENTIAL DIAGNOSES
• Scar
• Fetal lobulation
• Angiomyolipoma
KEY FACTS
PATHOLOGY
• Layer of connective tissue trapped from fusion of 2
metanephric elements in formation of kidney
• Deep diagonal groove extending from anterior surface of
upper pole of kidney into hilum
CLINICAL ISSUES
• Normal variant
DIAGNOSTIC CHECKLIST
• Absence of parenchymal loss useful to differentiate it from
cortical scar
• Characteristic location
• Increased echogenicity on ultrasound
• Fat density on CT
• Fat signal intensity on MR
(Left) Longitudinal
transabdominal ultrasound
demonstrates a junctional
parenchymal defect ſt as a
small triangular echogenic
focus between the upper and
middle 1/3 of the kidney.
(Right) Longitudinal
transabdominal ultrasound
demonstrates an
interrenuncular septum ſt as
a thin echogenic line
communicating with the renal
sinus.
(Left) Longitudinal
transabdominal ultrasound
demonstrates an
interrenuncular septum ſt as
a thin echogenic line at the
upper to middle 1/3 of the
kidney. Note the fetal
lobulation as indentations
between the medullary
pyramids in this infant. (Right)
Coronal T1 C+ FS MR of the
kidneys shows bilateral
interrenuncular septa ſt as
complete clefts extending into
the renal sinus.
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