Inflammatory Hepatocellular Adenoma Mimicking Focal Nodular Hyperplasia That Grew during Pregnancy and Changed Its Appearance on Magnetic Resonance Imaging after Delivery

Abstract

We reported a notable case of inflammatory hepatocellular adenoma that grew during pregnancy, consequently changing its appearance on magnetic resonance imaging remarkably. A 5-months-pregnant 35-year-old woman presented with a 37-mm liver nodule that had been diagnosed as focal nodular hyperplasia 3 years earlier. She had never used oral contraceptives. After 2 months, the nodule grew to 57 mm. The patient delivered a full-term infant without complications. Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging performed after delivery revealed markedly different findings compared with the first images. A liver biopsy was performed, and the tumor was diagnosed as inflammatory hepatocellular adenoma.

Keywords: hepatocellular adenoma; magnetic resonance imaging; pregnancy; ultrasonography.

Figure 1.

MRI findings. (A-C) Time course of EOB-MRI and (d) T2-weighted imaging before enhancement. A: EOB-MRI performed three years prior to presentation. (a, b) The tumor enhanced rapidly and homogeneously in the arterial (a) and parenchymal (b) phases. In the hepatobiliary phase (c), the nodule was visible as a hypointense region with a hyperintense rim. B: EOB-MRI performed two days after delivery. (a) The tumor had grown and was enhanced gradually from the periphery in the arterial phase, and (b) the enhancement spread to the center in the parenchymal phase. (c) In the hepatobiliary phase, the tumor appeared as a clear perfusion defect. C: EOB-MRI performed four months after delivery. The tumor had decreased in size and was similar to that observed three years earlier. (a, b) The enhancement pattern resembled that observed at the first EOB-MRI procedure. (c) The tumor was visible as a heterogeneous hypointense area. (d) No atoll signs were observed on T2-weighted imaging throughout the course of this case. EOB-MRI: gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging

Figure 2.

US findings. A: Time course of the tumor during the pregnancy. (a) Two months before consultation (3 months of pregnancy), the tumor measured 25.9 mm in diameter. (b) US at the time of consultation (5 months of pregnancy) showing that the tumor had grown to 37.9 mm in diameter. (c) Two months later, the tumor had grown to 57 mm in diameter. B: Contrast-enhanced US using Sonazoid at (d, e) 7 months of pregnancy and (f, g) 2 months after delivery. (d) In the vascular phase, the tumor was enhanced from the central to peripheral regions and showed a spoke-wheel appearance. (e) In the Kupffer phase, the tumor enhancement matched that of the surrounding parenchyma. (f) The tumor was enhanced homogeneously in the vascular phase, and a spoke-wheel appearance was not seen. (g) The tumor was heterogeneously enhanced in the Kupffer phase. US: ultrasonography

Figure 3.

Histological findings of the biopsy. (a) Hematoxylin and Eosin staining. (b) Silver stain. The tumor comprised three or more tumor cells with no atypia and was lined with a thick trabecular pattern. Irregular sinusoidal dilation and inflammatory infiltration are observed. A small number of typical unpaired arteries are observed. Immunohistochemistry: (c) glutamine synthetase is negative in the tumor (right), while zone 3 hepatocytes are positive in the normal liver (left). No focal patchy positivity is observed. Based on all of these findings, the nodule was diagnosed as inflammatory hepatocellular adenoma. (d) SAA was positive, whereas (e) β-catenin positivity in the nucleus and loss of L-FABP (data not shown) were not observed. L-FABP: liver fatty acid binding protein, SAA: serum amyloid A