ABDOMINAL AND GASTROINTESTINAL RADIOLOGY
Year : 2010 | Volume
: 20 | Issue : 1 | Page : 69--71
Paradoxical hepatic tumor: Undifferentiated embryonal sarcoma of the liver
Kushaljit Singh Sodhi1, Elhamy Bekhitt1, Christian Rickert2,
1 Department of Medical Imaging, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
2 Department of Pathology, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
Kushaljit Singh Sodhi
Department of Medical Imaging, Royal Children«SQ»s Hospital, Melbourne, Victoria 3052
Undifferentiated embryonal sarcoma (UES) is a rare primary malignant tumor of the liver that typically presents in late childhood. We report a case of primary UES, which had a typical paradoxical appearance on different imaging modalities.
|How to cite this article:|
Sodhi KS, Bekhitt E, Rickert C. Paradoxical hepatic tumor: Undifferentiated embryonal sarcoma of the liver.Indian J Radiol Imaging 2010;20:69-71
|How to cite this URL:|
Sodhi KS, Bekhitt E, Rickert C. Paradoxical hepatic tumor: Undifferentiated embryonal sarcoma of the liver. Indian J Radiol Imaging [serial online] 2010 [cited 2021 Jan 27 ];20:69-71
Available from: https://www.ijri.org/text.asp?2010/20/1/69/59760
Undifferentiated embryonal sarcoma (UES) represents 9-15% of all hepatic tumors in children and is the third most common malignant hepatic tumor in children after hepatoblastoma and hepatocellular carcinoma. However, it is still a rare entity and, till date, less than 150 cases of UES have been reported. , Recent published data indicate that modern surgical procedures along with neoadjuvant or adjuvant chemotherapy can lead to an increase in survival rates. Early diagnosis and prompt therapy are thus important. 
We present the radiological findings of UES of the liver in a 7-year-old child. These cases can be diagnostically challenging because of the discordance between the appearances at CT scan/MRI and at USG. While CT scan and MRI demonstrated a cyst-like mass, USG revealed a solid-looking mass lesion. Familiarity with the paradoxical findings of UES of the liver is useful in the differential diagnosis of primary hepatic tumors in childhood.
A 7-year-old girl presented with a 2-week history of shoulder-tip pain, progressive fever and right upper quadrant pain. She had no history of vomiting, diarrhea or weight loss.
On examination, she was febrile and had a palpable, firm mass in the right upper quadrant. She had a temperature of 388C, heart rate of 145/min and respiratory rate of 28/ min. Blood culture was negative and did not grow any organism. Serology for cytomegalovirus (CMV), Ebstein-Barr virus, hepatitis B surface antigen, hepatitis C and hydatid was negative. Serum a-fetoprotein levels of 0 and serum HCG ,,,, Although it represents about 9-15% of all hepatic tumors in children, only about 150 cases have been reported in the literature. ,
The histogenesis of this tumor still remains undetermined. Some authors have suggested that it is the malignant counterpart of mesenchymal hamartoma.  Several cytogenetic abnormalities, including TP53 mutation, chromosome 19q and 7q, have been investigated to understand the histogenesis of this tumor. 
CT scan typically demonstrates a large mass with cystic attenuation, while on MRI, large portions of the mass are hypointense on T1W images and have a high signal intensity on T2W images. Areas of high signal intensity on T1W images and low signal intensity on T2W images may also be seen in some cases due to intratumoral hemorrhage. ,,,,, With gadolinium administration, there is mild heterogeneous enhancement with predominant lack of enhancement in most of the tumor, consistent with extensive central necrosis or cystic change. Moon et al.  have also described the discrepancy of internal architecture on USG and CT scan as one of the important characteristics of UES.
Buetow et al.,  who have studied the pathological basis of imaging findings in cases of UES, have stated that there is an excellent correlation between the predominantly solid USG appearance and the pathologic findings in these liver tumors, whereas there is discordance between the CT scan/MRI findings and the USG and pathologic analysis.  According to the authors, the increased water content within the abundant myxoid stroma of UES accounts for the attenuation lower than that of soft tissue on CT scans and the high signal intensity on T2W MRI images, as seen in our case. Similar findings have also been reported on CT scan and MRI with other myxomatous tumors. UES, in 83% of the cases, appears predominantly solid at gross examination.  It is not surprising that MRI is more likely than CT scan to depict areas of hemorrhage, as was seen in our case.
Histopathologically, the tumor has a variable but distinctive sarcomatous appearance. UES is composed of spindle- and stellate-shaped sarcomatous cells, with marked nuclear pleomorphism or multinucleate forms, closely packed in whorls or sheets or scattered loosely in a myxoid ground substance. , The cell borders are poorly defined. Pleomorphic multinucleated giant cells are relatively frequent.
The differential diagnosis in this 7-year-old child included UES, hepatocellular carcinoma (HCC), complicated hydatid cyst, hematoma and abscess (amebic, bacterial). We considered HCC and EUS, as HCC is the most common primary malignant hepatic tumor in children more than 5 years of age while UES is typically seen in children in the age group of 6-10 years and, along with HCC, accounts for the majority of all malignant hepatic neoplasms in children more than 5 years old. However, HCC was considered less likely as the liver was noncirrhotic, the lesion appeared cystic on CT and the patient did not have elevated a-fetoprotein levels. Complicated hydatid cyst and liver abscess were considered as the patient was febrile and imaging features were suggestive. However, blood culture was negative and did not grow any organism and serology for hydatid was also negative. Although we were not provided with a direct history of trauma, it was considered in the differential list as the history is not always forthcoming and USG features were quite suggestive.
Until the late 1980s, survival was considered poor for patients with UES. However, survival outcome in the early 1990s has improved considerably with the use of multidrug combination chemotherapy, including sarcoma protocols. 
Awareness about these discordant and paradoxical USG and CT scan findings in UES of the liver is useful for the differential diagnosis of primary hepatic tumors in childhood.
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