Diagnostic ultrasound ( PDFDrive )

352 PART II Abdominal and Pelvic Sonography
appearance of an AML: an echogenic lesion with shadowing. As
mentioned earlier, although several distinguishing features have
been suggested, there is signiicant imaging overlap between
classic AMLs and small, echogenic RCCs. Involvement of regional
lymph nodes and extension of AMLs into the IVC have also
been described. 207 Further, it may be diicult to diferentiate a
large, exophytic AML from a large, retroperitoneal liposarcoma
(Fig. 9.59). Helpful features that may allow diferentiation from
liposarcomas include (1) a defect in the renal parenchyma where
the tumor originates and (2) the presence of enlarged vessels
and other associated AMLs. 208 he blood vessels in an AML lack
normal elastic tissue and are prone to aneurysm formation and
hemorrhage. 209 Color low Doppler sonography appears to be
the best imaging modality to detect an intratumoral pseudoaneurysm
in a hemorrhagic AML. 210
Small, asymptomatic AMLs may be followed for growth; if
large, symptomatic, or hemorrhaged, surgery is oten performed.
FIG. 9.59 Exophytic Angiomyolipoma. Sagittal sonogram shows
a large, exophytic, echogenic angiomyolipoma.
If possible, renal-sparing surgery is preferable, because these
tumors are benign or may be multiple. Embolization may also
be used to treat actively bleeding AMLs. 211
Lymphoma
Kidney
he kidney does not contain lymphoid tissue. hus lymphomatous
involvement of the kidney occurs from either hematogenous
dissemination or contiguous extension of retroperitoneal
disease. Renal involvement occurs more oten in the setting
of non-Hodgkin lymphoma than Hodgkin lymphoma. By the
time renal disease is evident, disseminated disease is usually
apparent. Urinary tract symptoms are uncommon. Occasionally,
lank pain, a lank mass, or hematuria may occur. Nonetheless,
at autopsy, renal involvement is found in one-third of lymphoma
patients, 212 and bilateral renal disease is more common than
unilateral disease. Isolated renal disease may be seen in patients
undergoing treatment.
he sonographic appearance of renal lymphoma depends
on the pattern of involvement. Focal parenchymal involvement
may appear as solitary or multiple nodules. hese masses appear
homogeneous and hypoechoic or anechoic (Fig. 9.60). hey may
simulate cysts; however, increased through transmission is
absent. 213,214 As with other iniltrating renal tumors, iniltrating
lymphoma is manifested by maintenance of a reniform shape
despite disruption of renal architecture. he kidney may be
enlarged (Fig. 9.61). Tumor may invade the renal sinus and destroy
the echogenic, central echo complex. 215 Direct invasion of the
kidney by large retroperitoneal lymph node masses may occur
with associated vascular and ureteral encasement. Large, retroperitoneal,
hypoechoic conglomerate adenopathy may extend
into the renal pelvis and cause hydronephrosis. he absence of
renal venous invasion, despite extensive retroperitoneal and renal
A
B
FIG. 9.60 Renal Lymphoma. (A) Transverse sonogram shows a subtle right midpole contour deformity and vague hypoechoic lesion.
(B) Contrast-enhanced CT conirms mildly border-deforming renal lesion and shows contralateral lesions.