Diagnostic ultrasound ( PDFDrive )

356 PART II Abdominal and Pelvic Sonography
well-deined peripheral mass is seen. Carcinoid tumor is a rare
renal tumor that tends to be solid, with peripheral or central
calciication. 230 Other benign tumors that have been described
include lipomas and hemangiomas.
Renal sarcomas are aggressive tumors that account for
approximately 1% of all malignant renal tumors. Leiomyosarcoma
is the most common, representing 58% of all renal sarcomas.
Hemangiopericytoma represents 20%. At sonography, these
tumors cannot be distinguished from RCC. Liposarcoma accounts
for 20% of all renal sarcomas. Depending on the amount of
mature fat present, these tumors can be quite hyperechoic and
indistinguishable from AMLs. Less common sarcomas include
rhabdomyosarcoma, ibrosarcoma, and osteogenic sarcoma.
Wilms tumor may rarely occur in adults and cannot be diferentiated
radiologically from RCC.
Bladder
Mesenchymal bladder tumors also are rare, accounting for about
1% of all bladder tumors. Leiomyoma is the most common
benign bladder tumor. Most leiomyomas arise from the submucosa
near the bladder trigone. 231 hese tumors may show intravesical
(63%), intramural (7%), or extravesical (30%) growth. 231 At
sonography, a well-deined, round or oval, solid mass will be
seen. Cystic degeneration may occur. Neuroibromas of the
bladder may be seen as an isolated inding or may occur with
difuse systemic disease. hese tumors are similar to leiomyomas
at ultrasound. Cavernous hemangiomas are most oten found
in the dome and posterolateral bladder wall. 232 At sonography,
two types have been described: (1) a round, well-deined, solid,
hyperechoic, intraluminal mass that is highly vascular on color
Doppler ultrasound and (2) difuse wall thickening with multiple
hypoechoic spaces and calciication. 232 Bladder pheochromocytomas
are rare; they account for only 1% of all pheochromocytomas.
231 Patients may have symptoms that include headaches,
sweating, and tachycardia related to bladder distention or voiding.
Pheochromocytomas arise in the submucosa and may be found
anywhere in the bladder, but usually at the dome. At ultrasound,
a well-deined, solid, intramural bladder wall mass will be seen
(Fig. 9.66). Malignant mesenchymal bladder tumors are rare;
the most common are leiomyosarcomas and rhabdomyosarcomas.
At sonography, a large, iniltrative mass is seen.
RENAL CYSTIC DISEASE
Cortical Cysts
Simple renal cysts are benign and luid illed. Although their
exact pathogenesis is unknown, they likely originate from distal
convoluted or collecting ducts. 233 Incidence of simple cysts
increases with advancing age, and they are found in at least
A
B
C
FIG. 9.66 Bladder Pheochromocytoma. (A) Suprapubic image
of the bladder shows a smooth surface to a solid bladder mass.
(B) Transvaginal scan with partial bladder emptying shows the mucosa
is intact over the submucosal nodule. (C) Color Doppler image
conirms lesional vascularity. (With permission from Damani N,
Wilson S. Nongynecologic applications of transvaginal ultrasound.
Radiographics. 1999;19:S179-S200. 83 )