Diagnostic ultrasound ( PDFDrive )

364 PART II Abdominal and Pelvic Sonography
ultrasound diagnosis of localized cystic disease, although CT or
MRI conirmation is typically needed. In addition, CT (or MRI)
better shows the thick, ibrous, encapsulating capsule characteristic
of MLCN. 258
Neoplasm-Associated Renal Cystic Disease
Acquired Cystic Kidney Disease
Acquired cystic kidney disease (ACKD) occurs in the native
kidneys of patients with renal failure undergoing either hemodialysis
or peritoneal dialysis. ACKD afects 40% to 90% of these
patients, depending on the duration of dialysis. 127,128,247,259 RCC
occurs in 4% to 10% of patients with ACKD. 259 he pathogenesis
of ACKD is speculative. Epithelial hyperplasia caused by tubular
obstruction resulting from toxic substances plays some role in
the development of both cysts and tumors. 259 On histology,
multiple small cysts (0.5-3 cm) involving both renal cortex and
medulla are found. Hemorrhage into cysts is common. Ultrasound,
CT, and MRI are useful in the evaluation and follow-up of patients
with ACKD and its complications. 127,128,260 ACKD and tumor
development persist even ater successful renal transplantation.
ACKD and tumors may develop in renal allograts during dialysis
therapy. 261
At sonography, inding three to ive cysts in each kidney in
a patient with chronic renal failure is diagnostic. 261 he cysts are
usually small, as are the kidneys, which typically are quite
echogenic (Fig. 9.76). Internal echoes are seen in cysts that have
hemorrhaged. Tumors are solid or cystic with mural nodules.
Von Hippel–Lindau Disease
VHL disease is transmitted as an autosomal dominant gene with
variable expression and moderate penetrance. Its incidence is
1 : 35,000. 248 he predominant signiicant abnormalities include
retinal angiomatosis, central nervous system hemangioblastomas,
pheochromocytomas, and renal cell carcinoma
(40%). RCC in VHL patients usually is multifocal (75%-90%)
and bilateral (75%). hese patients are oten ofered nephronsparing
surgery. In addition, renal cysts, the most common
inding in VHL disease, are found in 76% of patients. 262 Cysts
range from 0.5 to 3.0 cm in size and are mostly cortical based.
Ultrasound may be used as an initial screening test for VHL
disease. However, CT or MRI is better for detection of the small,
multifocal, bilateral tumors found in VHL disease and are the
preferred modalities for surveillance ater nephron-sparing
surgery (Fig. 9.77).
Tuberous Sclerosis
Tuberous sclerosis is an autosomal dominant syndrome characterized
by mental retardation, seizures, and adenoma sebaceum.
Many cases also result from spontaneous mutation. he incidence
ranges from 1 : 9000 to 1 : 170,000. 263 Associated renal lesions
include cysts, AML, and RCC (1%-2%). 248 he renal cysts vary
in size from microscopic to 3 cm. At sonography, if only cysts
are present, it may be diicult to diferentiate tuberous sclerosis
from ADPKD. he presence of cysts and multiple AMLs suggests
FIG. 9.76 Acquired Cystic Kidney Disease. Sagittal sonogram
demonstrates an echogenic small kidney containing multiple cysts. A
small amount of intraperitoneal dialysate luid is seen.
A
B
FIG. 9.77 Von Hippel–Lindau Disease. (A) Transverse and (B) sagittal sonograms show multiple small, complex cystic lesions.