Diagnostic ultrasound ( PDFDrive )

CHAPTER 39 The Fetal Urogenital Tract 1353
FIG. 39.22 Congenital Mesoblastic Nephroma. Longitudinal scan
of a 35-week fetus shows a large, heterogeneous solid mass (calipers)
replacing most of the right kidney, except for the upper pole (arrow).
FIG. 39.23 Normal Adrenal Gland. Longitudinal scan of a 31-week
fetus demonstrates the Y- or V-shaped adrenal gland (arrow) at the
superior border of the kidney (K).
Mesoblastic nephroma is usually seen as a moderately echogenic,
solid mass completely replacing the kidney or localized to part
of the kidney 111 (Fig. 39.22). he mass may demonstrate increased
vascularity and cystic components. Polyhydramnios is a frequent
association 110,112 and may lead to preterm labor and preterm
birth. Perinatal complications are likely, including acute fetal
distress, neonatal hypertension, and hypercalcemia. 110 Other
reported fetal renal tumors include an intrarenal neuroblastoma,
a tumor much more frequently associated with the adrenal
gland. 113
Adrenal Mass
At the end of the irst trimester, the normal adrenal glands appear
as pyramid-shaped hypoechoic structures at the superior aspect
of the kidneys. hey are quite prominent, approximately half
the size of the kidney. he size of the adrenal gland increases
with gestation, but relatively less than the kidney. During the
second and third trimesters, corticomedullary diferentiation is
apparent, with a hyperechoic medulla and a hypoechoic cortex.
On longitudinal sonogram, the adrenals are seen as V- or
Y-shaped structures superior to the kidneys (Fig. 39.23).
Abnormalities of the adrenal gland include hemorrhage, cyst,
hypertrophy, and tumor. he diferential diagnosis for fetal
suprarenal masses includes those of adrenal origin (including
adrenal neuroblastoma, adrenal hemorrhage, adrenal cyst, and
rarely adrenal cortical adenoma or carcinoma) and those of
extraadrenal origin (including those of renal origin [such as
mesoblastic nephroma, duplication anomaly with hydronephrosis,
upper-pole cystic dysplasia, urinoma], intraabdominal
pulmonary sequestration, enteric duplication cysts, splenic
cysts, and lymphangioma) (Table 39.3). 114-116
Neuroblastoma may occur anywhere along the sympathetic
chain, but 90% are located in the adrenal gland. he prenatal
sonographic appearance is variable and ranges from a complex
cystic mass with thick septations (the most common presentation),
to a uniformly echogenic solid mass (Fig. 39.24), to rarely
calciied. 116-118 Importantly, a complex cystic neuroblastoma is
FIG. 39.24 Adrenal Neuroblastoma. Longitudinal scan shows a
large echogenic solid mass (calipers) adjacent to the upper pole of the
left kidney (K). (Courtesy of John R Mernagh, MD, McMaster University
Medical Center, Hamilton, Ontario.)
TABLE 39.3 Suprarenal Masses
Adrenal Origin
Neuroblastoma
Hemorrhage
Cyst
Adenoma or carcinoma
Nonadrenal Origin
Renal origin: tumor (e.g.,
mesoblastic nephroma),
duplication anomaly,
upper-pole cystic
dysplasia, urinoma
Intraabdominal pulmonary
sequestration
Enteric duplication cyst
Splenic cyst
Lymphangioma