Diagnostic ultrasound ( PDFDrive )

354 PART II Abdominal and Pelvic Sonography
A
B
FIG. 9.63 Diffuse B-Cell Bladder Lymphoma. (A) Transverse sonogram shows a large irregular mass that replaces the bladder. (B) Corresponding
contrast-enhanced CT shows a bulky mass that occupies the entire bladder lumen. (Courtesy of R. Brooke Jeffrey, MD.)
leukemic iniltration. 220 Renal leukemia may also be manifested
as a coarsened renal echo pattern with distortion of the central
sinus echo complex. 221 Alternatively, the kidneys may be diffusely
echogenic. Focal masses may be single or multiple. 222
hese patients are prone to renal, subcapsular, and perinephric
hemorrhage.
Metastases
Kidney
Renal metastases are typically clinically occult, but autopsy series
done before cross-sectional imaging documented an incidence
of 2% to 20%. 223 he true prevalence of renal metastases in the
era of cross-sectional imaging is unknown, but the prevalence
of subclinical, imaging-apparent renal involvement is likely greater
than estimated by gross autopsy.
Spread to the kidneys is by a hematogenous route. he most
common primary tumors giving rise to renal metastases are
(1) lung carcinoma, (2) breast carcinoma, and (3) RCC of the
contralateral kidney. 120 Other tumors that may produce renal
metastases include colon, stomach, cervix, ovary, pancreas, and
prostate. 120 Renal metastatic spread may manifest as a solitary
mass, multiple masses, or a difusely iniltrating mass that
enlarges the kidney. Choyke et al. 224 evaluated 27 patients with
renal metastases and found that metastases are usually multifocal;
however, large, solitary tumors may occur that are otherwise
indistinguishable from primary RCC. Also, a new renal lesion
in a patient with advanced cancer is more likely a metastatic
than a primary tumor. If a single renal lesion is discovered synchronously
in a patient with a known primary tumor, or with a
tumor in remission with no evidence of other metastases, renal
biopsy is necessary to diferentiate a primary RCC from a renal
metastasis.
Contrast-enhanced CT is the best radiographic technique for
detecting renal metastasis, although ultrasound is almost as
sensitive. 224 At sonography, the appearance depends on the pattern
of involvement. A solitary metastasis will be seen as a solid
mass indistinguishable from RCC; this oten occurs with colon
carcinoma. 224 Central necrosis, hemorrhage, and calciication
may be evident. Multiple metastases usually appear as small,
poorly marginated, hypoechoic masses. Involvement of the
perinephric space is possible, particularly with malignant melanoma
and lung cancer. 224 Iniltrating renal metastases are particularly
subtle at ultrasound; as with other iniltrating processes,
the only manifestation at sonography may be an enlarged, but
still reniform, kidney (Fig. 9.64).
Ureter
Ureteral metastases are rare; evidence of difuse metastases
elsewhere is seen in 90% of cases. 225 Metastatic disease to the
ureter occurs by hematogenous or lymphatic dissemination.
Tumors that may secondarily involve the ureter include melanoma,
bladder, colon, breast, stomach, lung, prostate, kidney,
and cervical lesions. hree types of ureteral involvement occur:
(1) iniltration of the periureteral sot tissues, (2) transmural
involvement of the ureteral wall, and (3) submucosal nodules.
With the irst two types, imaging may demonstrate strictures
with or without an associated mass. Intraluminal lesions may be
shown with the third type. 188 At sonography, the site of tumor
involvement may be seen if a mass is present. Usually, however,
the only manifestation of ureteral involvement is secondary
hydronephrosis.
Bladder
Although rare, metastases to the bladder may occur with malignant
melanoma, lung, gastric, or breast cancer. he appearance