A 26-year-old woman with a history of duodenal ulcer and
esophagogastric reflux disease, presented with epigastric pain
radiating to the left upper quadrant for 2 days. The patient also
had fever and nausea. A guaiac test was negative. There was no
associated hematemesis or hemop-tysis. The patient was not anorexic
and denied loss of weight. Her abdominal examination revealed right
upper quadrant tenderness on palpa-tion. Hepatic biochemical tests
showed abnormal liver function and increased billirubin. There was
also slightly in-creased white blood cell count.
An ultrasound study demonstrated a large left upper quadrant
mass in the splenetic hilar. A subsequent CT scan revealed a large
mass involving the lateral segment of the left lobe of the liver,
stomach, and splenic hilum, which contained cystic and solid areas
(figure 1). A liver-spleen scan-SPECT (single photon emission
computed tomography) with admini-stration of Technetium 99m-labeled
sulfur colloid demonstrated a large defect involving the medial
aspect of the spleen which appeared to com-press the left lobe of
the liver anteriorly (figure 2).
Based on the imaging findings, the radiologic differential
diagnoses include: 1) primary hepatic malignant neoplasm, such as
necrotic hepato-cellular carcinoma; 2) primary hepatic
non-malignant neoplasm with un-usual presentations, such as focal
nodular hyperplasia (FNH); 3) gas-tric neoplasm with direct
invasion of liver; 4) lymphoma; 5) metastatic di-sease from unknown
origin; and 6) infection, although this is less likely.
The patient subsequently under-went surgery. A large left upper
qua-drant tumor originating from the left lobe of the liver was
identified. This mass did not involve the stomach. Needle
aspiration showed profuse bleeding. Frozen section examination
revealed necrotic tissue. Gross path-ology examination demonstrated
a 10-cm well-demarcated mass, which had a multilobulated nodular
appearance with a pale-yellow necrotic center and a thin peripheral
rim (figure 3). Microscopic examination proved this mass to be FNH
of the liver with multiple areas of necrosis. There was no evidence
of hepatocyte atypia.
FNH occurs most commonly in middle-aged women. While its cause
is not clearly understood, a relationship with oral contra-ceptives
has been demonstrated.
FNH is usually found incidentally at surgery or autopsy.
Occasionally, it presents as a asymptomatic upper abdominal mass.
Com-plications are rare, and malignant trans-formation does not
occur. Pathologically, FNH lesions are usually < 5 cm in
diameter; most have central scars containing thick-walled vessels
that provide excellent arterial blood supply. Thus, infarction,
necrosis, and hemorrhage are extremely unusual.
Usually, a pseudocapsule is present and the bulk of the lesion is
composed of regenerating liver nodules with a fibrous center and
portal areas containing proliferating ducts.
There is often excellent correlation be-tween the pathologic
features of FNH (a characteristically homogenous hypervascu-lar
tumor with a central scar and both he-patocellular and
), and the imaging characteristics of various modalities, notably
MR imaging, CT, sonography, and scintigraphy. Each of these
modalities offer different advantages for the detection and
characterization of FNH. In many cases, it is possible to obtain a
prospective imaging diagnosis of FNH; however, in some cases, the
distinction between FNH and other primary hepatic neoplasms is not
possible. In these latter cases, close imaging follow-up, needle
biopsy, or surgical resection may be necessary.
Since FNH lesions contain sufficient number of Kupper cells,
these tumors usually concentrate or hyperconcentrate sulfur
colloid. Thus, in the majority of cases they appear
indistinguishable from normal hepatic parenchyma on liver-spleen
scans. On two-dimensional ultrasound,
the lesions are usually homogeneous and isoechoic, and the central
scar is rarely depicted. Color Doppler ultrasound, however, shows
rich vascularity, in 25% of cases the vessels demonstrate a
stellate pattern. Doppler spectra show medium- to high-flow
velocities. On unen-hanced CT scans, all the lesions appeared
homogeneous and isodense; in 80% of cases, a central hypodense area
corresponding to the scar is demonstrated clearly. On triple-phase
dynamic CT scans, the peripheral parenchyma of these lesions
demonstrate transient and marked hyperdensity, with a gradual
return to isodensity of the normal hepatic tissue in the
parenchymal and venous phases. Conversely, the central scar density
is hypodense in the arterial phase and increases progressively in
the later phases, ultimately reaching higher values than the
surrounding lesion. On MR images,
the lesion appears isointense on T1-weighted images and isointense
or slightly hyperintense on T2-weighted images. The central scar is
hypointense on T1-weighted images and hyperintense on T2-weighted
Two-dimensional ultrasound alone has poor specificity. The
addition of color Doppler increases sonographic specificity to
100%, but the combined ultrasound exam still has low sensitivity
for FNH. Dynamic CT sensitivity has been reported as 80% and MRI
sensitivity as 40%.
In another study, it was reported that the best imaging modality
for the diagnosis of FNH was enhanced MRI, with a sensitivity of
70% and a specificity of 98%.
FNH without a central scar
and with intralesional bleeding has been reported.
In such cases, preoperative imaging diagnosis becomes impossible.
In our case, intra-lesional necrosis and bleeding was probably
secondary to the size of the lesion and to the lack of a central
scar containing the large blood vessels.
In atypical cases such as this one, considerable overlaps can
in the appearance of various pathologic entities that occur in the
liver, such as hepatic hemangioma, adenoma, FNH, intrahepatic
cholangiocarcinoma, metastatic disease, hepatocellular carcinoma,
regenerating nodules, adenomatous hyperplastic nodules, and
abscess. Another study demonstrated that only a small number of
patients with FNH (2 of 12 cases) have classic or typical triphasic
helical CT manifestation.
In these cases, additional imaging studies, such as a Technitium
99m-sulfur colloid liver scan, an enhanced MR scan, or a
percutaneous biopsy, may be crucial for correct diagnosis.
In summary, it is important for radiologists to be aware of the
uncommon appearance of liver FNH including, in this case, lack of a
central scar and the presence of cystic areas. Familiarity with
these varied CT and MRI imaging features will permit a more
accurate diagnosis and prevent a false diagnosis.
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Prepared by Feng Tao, MD, Department of Radiology, and Frank
Bieuei, MD, Department of Pathology, Lenox Hill Hospital, New York,
NY; and Richard A. Heiden, MD, Department of Radiology, Interfaith
Medical Center, Brooklyn, NY.