Diagnostic ultrasound ( PDFDrive )

606 PART II Abdominal and Pelvic Sonography
K
A
B
FIG. 17.7 Ultrasound-Guided Biopsy of Renal Mass. (A) Longitudinal image shows a 2-cm solid mass (arrows) extending from lower pole
of the left kidney (K). (B) Mass was biopsied using an 18-gauge biopsy device, conirming renal cell carcinoma.
masses has increased and both biopsy accuracy and safety proiles
have improved. Current literature shows diagnostic rates for renal
mass biopsy of 85% to 92%. 72,73 Other authors have also shown
exceptional results, 74-76 but these studies are in some cases limited
by the mode of determining true-negative results, which is based
on stability on imaging follow-up. However, we know that the
lack of growth in a renal mass does not imply a true-negative
result, because 25% of renal tumors will not grow. 77 Nondiagnostic
biopsies are more common in cystic or nonenhancing masses
especially if small (<4 cm) or deep (>13 cm skin-to-tumor
distance). 73
It is helpful to keep in mind that the smaller the renal mass
is, the more likely it is to be benign. 78,79 In one large series, 46%
of tumors less than 1 cm were benign. 78 Cross-sectional imaging
has allowed accurate characterization of many benign renal
masses, notably benign cysts and fat-containing angiomyolipomas.
he problem is with the indeterminate, small, enhancing
renal mass, speciically the oncocytoma, small renal cell carcinoma,
and lipid-poor angiomyolipoma, which cannot be
reliably diferentiated by imaging. 80 For these reasons and because
a wider range of treatment options, including active surveillance
and ablation, is available to patients, renal mass biopsy is being
increasingly utilized. he current guidelines of the American
Urological Association state that renal mass biopsy is appropriate
for patients with a clinical stage 1 renal mass (conined to the
kidney and ≤7 cm) in whom a wide range of management options
are under consideration, ranging from surgery to observation.
When performed in the appropriate circumstances, biopsy may
afect a change in clinical management in 40% of patients. 74
Sonographic guidance can be used in the biopsy of kidneys
with difuse parenchymal disease. Insertion of the needle into
the cortex of the lower-pole renal parenchyma with tip directed
away from the central hilum under continuous real-time guidance
results in few complications and produces a tissue sample of
excellent quality for analysis. An 18-gauge biopsy needle provides
a specimen that is equivalent in diagnostic quality to the biopsy
specimen obtained by the traditional 14-gauge cutting needle. 81
In fact, Hergesell et al. 19 found a 99% success rate in obtaining
diagnostic tissue using an 18-gauge needle, with only 0.36% of
patients experiencing a signiicant bleeding complication. In this
series, postbiopsy ultrasound revealed a clinically occult hematoma
greater than 2 cm in 2% of patients. Similarly, asymptomatic
hemorrhage may be detected by CT in up to 90% of patients
ater uncomplicated kidney biopsy. 82 Arteriovenous (AV) istulas
may be seen in about 10% of patients immediately ater kidney
biopsy and usually resolve spontaneously (Fig. 17.8).
Clinically important bleeding is the most serious complication
ater kidney biopsy, occurring in 0.3% to 6.6% of patients. 16,17,23
Gross hematuria may occur in 5% to 7% and usually stops within
6 to 12 hours. 83 Microscopic hematuria occurs in up to 100% of
patients and should not be regarded as a complication.
Adrenal Gland
he most common indication for adrenal biopsy is to conirm
metastatic disease in a patient with an adrenal mass and a known
primary malignancy elsewhere. Currently, CT and MRI characterization
of adrenal masses has supplanted biopsy in many cases
in establishing benignity of an adrenal mass. Nevertheless,
occasional histologic diagnosis is required. In this case, CT
guidance is generally the preferred adrenal biopsy technique
because of the deep location of the adrenal glands in the retroperitoneum.
Percutaneous biopsy can yield a diagnosis in more
than 93% of patients. 84,85
he right adrenal gland is more accessible to ultrasound-guided
biopsy than the let adrenal gland because the right lobe of the
liver provides a sonographic window to optimize imaging (Fig.
17.9). Bright, echogenic, fat-containing adrenal masses and
homogeneous, thin-walled, luid-illed adrenal masses may not