Cover Illustration: A Case of Focal Nodular Hyperplasia of the liver
A 40-year-old woman presented with dull pain in the lower abdomen and a hepatic tumor was detected on abdominal ultrasonography. She had no history of taking oral contraceptive.
Color Doppler ultrasonography showed a well demarcated round tumor, 5 cm in diameter, with a large feeding artery behind the left lateral segment of the liver (Cover Illustration A). On dynamic computed tomography, the tumor originating from the left caudate lobe (Spiegel lobe) showed high attenuation on early phase (Cover Illustration B) and low attenuation on late phase. The tumor appeared heterogeneous, but central stellate scar formation was not visualized. Angiography demonstrated tumor staining in the caudate lobe from both the left and right hepatic artery, which formed a ‘spoked wheel appearance’ (Figure C). The tumor showed low-intensity signal on T1-weighted magnetic resonance imaging (MRI) and also irregular low-intensity signal on T2-weighted MRI (Figure D). Liver function test including tumor markers were within normal ranges. A diagnosis of focal nodular hyperplasia (FNH) was made. As a result of the fear of the patient with regard to the malignant potential of the tumor, the patient requested surgical removal.
At laparotomy, a round, well-demarcated tumor was located on the left caudate lobe of the liver. The patient underwent limited resection of the caudate lobe of the liver and the post-operative course was uneventful.
Macroscopically, the tumor was surrounded by fibrous capsule and the cut-surface was slightly swollen. Several septum formations were found inside (Figure E). Microscopically, there was a lack of portal tracts and central scar in the tumor. A few fibrous septa contained bile ducts and abnormal thickened arteries were found. The hepatic parenchyma was slightly hyperplastic in parts and formed by one-cell- or two- cell-thick hepatic plates. They were composed of normal-appearing hepatocytes with fatty change or cholestasia. Pathological diagnosis was focal nodular hyperplasia (Figure F).
(Masayoshi Inoue, Hidenori Ojima, National Cancer Center, Tokyo)
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