A 2-year-old female child was found a distention in the right abdomen by her parents inadvertently. She did not present any specific clinical symptoms herself. Ultrasound examination at the local hospital indicated liver cyst. The hepatic CT showed a large space-occupying lesion of the liver, considering hepatoblastoma. The child was then admitted to our hospital on March 29, 2019. The child has no history of febrile seizures, acute infectious diseases or any other specific disease. The child is the second child of the family, with birth weight 2800 grams and good condition except neonatal jaundice in the neonatal period. At the time of admission, there was no obvious abnormality in the physical examination. Tumor marker testing results showed that the alpha-fetoprotein was slightly elevated to 14.5 ng/ml (normally < 10 ng/ml), and others (carcinoembryonic antigen, ferritin) presented normal value.
The enhanced hepatic computed tomography (CT) scan revealed a large mass in the right lobe of the liver, with the size of 91.9mm × 125.4mm × 176.4 mm (Fig. 1). The boundary was clear. Multiple circular cystic densities were observed in the plain CT scan, and the CT value was 11hu. After enhanced scan, the tumor showed heterogeneous enhancement, with the CT value of 45hu. Low density cystic change enhancement was not significant, CT value of venous stage lesions was 66hu, and CT value of delayed stage lesions was up to 84hu. In summary, according to the CT scan, multiple macular necrosis and cystic degeneration were observed in the lesion, and the contrast enhanced scan showed slightly delayed enhancement. The CTA showed the hepatic artery supplied blood to the right lobe of the liver. The blood vessels were thickened, the tumor blood vessels were clustered in the tumor, showed a signal of vascular agglomeration. The hepatic segment of the inferior vena cava was obviously compressed and tapered, the middle hepatic vein and right hepatic vein were not shown. The left hepatic vein ran naturally, no obvious filling defect was observed. The right branch of the portal vein was compressed and tapered, and the left portal vein ran naturally. The tumor volume was about 1,329.55 cm3 and the remaining liver volume was about 219.56 cm3.
According to the hepatic CT findings, the tumor was considered to be malignant, possibly a hepatoblastoma. The surgical resection was then planned immediately. As the tumor was huge in volume and may be ruptured before surgery, an 11-day preoperative preparation is performed. Finally, the tumor was removed by enucleation method, thus saving the rest of the liver. Intraoperative exploration of the abdominal cavity showed the tumor was located in the right lobe and invaded the hilum and middle lobe of the liver, almost occupied the abdomen and pelvic cavity.
The size of the surgical resection was 180.0mm × 150.0mm × 80.0 mm and the actual tumour size was 170.0mm × 120.0mm × 78.0 mm (Fig. 2). The tumor cut surface is soft, fleshy, white-tan, and had areas of hemorrhage, necrosis and cyst formation. The cyst wall was intact and did not invade the surrounding area. Microscopic examination showed a tumor arranged in lobules, composed of loose myxoid mesenchyme surrounding ductal structures, with intervening vascular channels. The vascular size profile is small - capillary to small venules (Fig. 3). The mesenchyme was loose, edematous and mucoid degeneration, with scattered inflammatory cells, lymphocytes, monocytes and neutrophils. Some areas of the junction were composed of infantile regenerated hepatocytes and proliferated blood vessels. The Immunohistochemical staining revealed positive CK7 for the bile duct elements and positive CD34 for the lining endothelial cells of the vascular channels (Fig. 3). Interestingly, there were abundant blood vessels around the nodules and the margins of remaining hepatocytes, but few in the central region. The blood vessels are small, thin-walled vessels and presented like capillaries and venules. Together, a histological diagnosis of Hepatic Mesenchymal Hamartoma was confirmed by the microscopic examinations. Because of the distribution of abundant blood vessels around the nodules in the tumor, the mass was probably misdiagnosed as a hepatoblastoma on the hepatic CT imaging.
During the follow-up, the ultrasound showed that the size and shape of the liver changes after operation, the internal echo of liver is normal and evenly distributed. The structure of the vascular network was clear, and the intrahepatic bile duct did not expand. The liver function investigations and coagulation profile were within normal limits.