Ultrasound1 Robert

A. Lee,

MD

Figure 1. Transverse oval, sharply marginated, I = inferior vena cava.

#{149} I

William

Cbarboneau,

MD

sonogram of the liver (a) isoechoic mass (arrow)

and magnified US view of the left lobe (b) with an echogenic central scar (arrowheads)

HISTORY

U

A 24-year-old

woman

pain underwent trasonography

(CT)

, and

with

vague

scintigraphy

(Figs

ul-

1-3).

The US images demonstrated a 6-cm, sharply marginated, isoechoic mass in the lateral segment of the left lobe of the liver. The mass had a homogeneous architecture except for an echogenic band running through its middlc portion, which is consistent with a central scar (Fig 1). CT scans obtained before the administra-

Index

terms:

RadloGraphics I From the sembly. CRSNA,

954

U

Liver, 1990; Department

Received 1990

RadioGrapbics

and

focal

nodular

hyperplasia,

l0954-956 of Diagnostic

Radiology,

accepted

March

U

23,

1990.

Lee and

76 1 .3 1 1 4 #{149} Liver

neoplasms,

Mayo

First

Address

Clinic,

200 reprint

Charboneau

a 6-cm A

aorta,

=

.

FINDINGS

U

.

tion of contrast material showed the mass to be hypoattenuated, well circumscribed, and homogeneous (Fig 2a) During the arterial phase of dynamic CT scanning, the mass was inhomogeneous and hyperattenuated (Fig 2b). On slightly delayed scans, the mass was isoattenuated relative to the normal hepatic parenchyma (Fig 2c). Scintigraphy of the liven was performed with technctium-99m sulfur colloid. Planar images (Fig 3a) and axial single photon emission computed tomographic (SPECT) images (Fig 3b) were obtained and demonstrated a large mass with mildly increased uptake in the left lobe of the liven.

abdominal

diagnostic imaging with (US), computed tomography

show

St. SW,

requests

diagnosis Rochester,

MN 55905.

From

the

1989

RNSA

scientific

as-

toJ.W.C.

Volume

10

Number

5

a.

b. Figure 2. (a) Nonenhanced CT scan demonstrates an oval, wcll-marginatcd, hypoattenuated mass (arrows) in the lateral segment of the left lobe. (b) Dynamic CT scan obtained during artenial phase shows heterogeneous, hypcrattcnuated pattern of enhancement (arrowheads) (c) Dclayed CT scan shows the mass to be homogeneously isoattenuated relative to liver (arrows). .

C.

a. Figure creased

September

1990

3. Planar Tc-99m sulfur-colloid liver scan (a) and axial SPECT uptake in the mass located in the left lobe (arrows) S = spleen, .

Lee and

image *

Charboneau

=

(b) demonstrate gallbladder.

U

slightly

RadioGrapbics

in-

U

955

DIAGNOSIS: the liven. U

Focal

nodular

hyperplasia

of

DISCUSSION

Focal nodular hyperplasia is a benign hepatic tumor composed of nodules of hepatocytes and Kupffcr cells separated by fibrous septa. Characteristically, there is a central stellate scar of connective tissue with septa radiating toward the periphery. Bile duct proliferation occurs within the fibrous septa or between hepatocytes. Portal tniads and central veins are absent (1). Focal nodular hyperplasia occurs most frequently in the 3rd to 5th decades of life, with a 2 : 1 female preponderance. Patients with these tumors are usually asymptomatic and have normal liver function (1). The diagnosis of focal nodular hyperplasia may require correlation of findings from 5evenal different radiologic studies. On US scans, the tumors are usually homogeneous and well marginated. The echogenicity of the tumors is variable, with isoechoic and hypoechoic lesions being the most common, as reported by Welch et al (2) On CT scans obtained without contrast enhancement, focal nodular hyperplasia is usually hypoattenuated and homogeneous. After the intravenous administration of contrast material, the tumor usually becomes either hyperattenuated or isoattenuated, depending on the rate of contrast material injection and the time delaybefore scanning (2,3). The central scar is usually not seen on cither CT or US scans (2) In addition, central scarring is not specific for focal nodular hyperplasia. Scarring can also be seen in fibrolamellar hepatocellular carcinoma, hemangioma, and hepatic adenoma after hemorrhage or necrosis (3 ,4) Therefore, correlation of

ful in making the diagnosis. Since significant numbers of Kupffer cells are normally present in focal nodular hyperplasia, uptake equal to or greater than that in normal liven parenchyma can occur. In a review of the literature by Rogers et al (5), 58% of the cases of focal nodular hyperplasia showed uptake equal to that of normal parenchyma, 7% showed hyperconcentration of Tc-99m sulfun colloid, and were relatively photopenic. No other hepatic masses usually contam sufficient Kupffen cells to cause normal or increased uptake (5) However, rare instances of focally increased uptake due to hemangioma, hepatoblastoma, liver herniation, and hepatocellular carcinoma have been reported (1). 35%

.

U REFERENCES 1 . Friedman A, Fishman

cal disease. the liver, Baltimore: 2

.

biliary tract, pancreas, Williams & Wilkins,

T, Sheedy

P, et al.

Fo-

A, ed. Radiology

P, Johnson

of

and spleen. 1987; 183-

CM, et al.

Focal

nodular hyperplasia and hepatic adenoma: comparison of angiography, CT, US, and tigraphy. Radiology 1985; 156:593-595.

.

.

188. Welch

E, Radecki

In: Friedman

3

.

4

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5

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Matheu D, Bruncton C, Vasilc N. Hepatic

J, Drouillard adenomas

scm-

J, Pointrcau and focal

nodular hypcrplasia: dynamic CT study. Radiology 1986; 160:53-58. Friedman A, Lichtcnstein J, Goodman Z, Fishman E, Siegelman 5, Dachman A. Fibrolamellan hepatocellular carcinoma. Radiology 1985; 157:583-587. Rogers J, Mack L, Freeny P, Johnson M, Sones

P.

Hepatic

focal

nodular

graphy, CT, sonography, AJR 1981; 137:983-990.

hypcrplasia: and

anglo-

scintigraphy.

.

US and

CT

sulfur-colloid

956

U

RadioGrapbics

findings

liven

with

scans

U

those

from

is sometimes

Lee and

Tc-99m

help-

Charboneau

Volume

10

Number

5