Diagnostic ultrasound ( PDFDrive )

CHAPTER 52 The Pediatric Urinary Tract and Adrenal Glands 1813
A
B
C
D
E
FIG. 52.53 Posttransplant Lymphoproliferative Disorder
(PTLD). (A) and (B) Longitudinal and transverse gray-scale
images of right lower quadrant renal allograft reveal mild
collecting system dilation. *, Dilated renal pelvis. (C) and (D)
Transverse images demonstrate a large, ill-deined pelvic mass
that extends superiorly along the medial aspect of the kidney
(arrows). K, Kidney. (E) Coronal reformatted image from
computed tomography scan of pelvis shows the large pelvic
mass obliterating the distal right ureter with proximal ureteral
dilation (arrow). Arrowhead indicates portion of Foley catheter
within bladder.
dilated collecting ducts that relect sound. he cortex is frequently
compressed by the dilated medullary collecting ducts, leading
to a hypoechoic halo. Dilated cortical collecting ducts located
immediately beneath the renal capsule may be seen with highresolution
ultrasound (Fig. 52.54). hey tend to lie in parallel
columns with a distribution that is radial to the kidney as a
whole. 169 Renal size stabilizes or decreases over time. Macrocysts
are not usually noted at birth but may develop later in childhood.
Histologic hepatic involvement is present in all patients with
ARPKD. In embryonic life, biliary precursor cells form a periportal
sheet known as the “ductal plate” that is progressively remodeled
to generate intrahepatic bile ducts. A remodeling defect in patients
with ARPKD leads to intrahepatic ductal dilation and progressive
portal tract ibrosis. Patients who survive the neonatal period
may develop portal hypertension as a result of the periportal
ibrosis.