Adult primary undifferentiated (embryonal) sarcoma of the liver: A case report

XU Haifeng, MAO Yilei*, DU Shunda, CHI Tianyi, LU Xin, YANG Zhiying, SANG Xinting, ZHONG Shouxian, HUANG Jiefu 

Department of Liver Surgery, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Sciences, Beijing, China 

Introduction

Undifferentiated embryonal sarcoma of the liver (UESL) was first described by Stocker and Ishak in 1978 [1]. It is a rare tumor that most often presents in childhood between 6 to 10 years of age [2]. The adult patients diagnosed with UESL often show nonspecific symptoms with normal laboratory studies. Ultrasonography, CT, or MRI often reveals a cystic mass. Complete surgical resection plus pre- and/or post-operative systemic chemotherapy offers the possibility of a cure. We report a case of primary UESL in an adult with no specific symptoms, tumor marks, or image results. The diagnosis was established based on the resulting pathology from surgery.

Case report

The patient is a 36 year-old female lawyer complaining of an epigastric mass for about 1 month and dull upper abdominal pain for 2 weeks. One month ago, without any obvious reason she felt an epigastric mass. Two weeks later, she felt dull upper abdominal pain without fever, nausea, vomiting, diarrhea, jaundice, or radiation to other parts of the body. She was admitted to our hospital after a right upper quadrant ultrasound showed a 20cm×10cm cystic/solid mass in the left lobe of the liver. The patient was previously in good health with no history of smoking or drinking. She has no specific family history of cancer. Physical examination on admission showed a well-nourished female without jaundice, icteric sclera, spider naevi, or palmar erythema. Cardiopulmonary examination was unremarkable. The abdomen was soft. There was deep tenderness on palpation without rebound in the left epigastric area, and the liver could be palpated 15cm below xiphoid and 2cm below the right lower costal margin. Laboratory tests showed normal blood cell counts, liver function, renal function, and coagulation time. Virus markers of hepatitis B were negative, and AFP, CEA, CA199 were normal. Abdominal computed tomography (CT) without contrast showed a 19.7cm×9.5cm cystic/solid lesion with a few internal septations and well-defined borders, with papillary protrusion extending into the cystic cavity, in the left lobe of the liver. The lesion was predominantly hypodense with a CT value of -15~39 HU (Figure 1). On dynamic contrast CT of the portal vein period, there was a slight enhancement of the cystic cavity with a CT value of -9~43 HU (Figure 2), and on contrast CT of the delay period, papillary protrusion showed a CT value of 31~75 HU (Figure 3). The initial diagnosis upon the above examinations was intrahepatic biliary cystadenoma or cystadenocarcinoma. 

The patient underwent a left partial hepatectomy under general anesthesia. During the operation, a 30cm×25cm×15cm cystic/solid mass with ruptured capsule and diaphragm invasion was located at the left lobe of the liver, and there were myxoid stroma and fishmeat-like tissue noted inside the cyst. The right hepatic lobe was normal and no other tumor was found in the abdominal cavity. A portion of the tumor wall was sent to pathology laboratory for intra-operative frozen section, and the report suggested myxoid stroma with separated malignant cells. Subsequently, partial hepatectomy including the lesion and part of the normal liver tissue was performed. The final pathology diagnosis was undifferentiated embryonal sarcoma of the liver. The patient recovered uneventfully after the surgery.

DISCUSSION

Primary undifferentiated embryonal sarcoma of the liver is a very rare tumor in adults. To our knowledge, only about ten cases of primary UESL in adults have been reported world-wide in the literatures as of 2007 [3,4,5,6,7,8]. 

The etiology of UESL is unclear, and the exact cellular origin and the mechanisms of its carcinogenesis remain undetermined. Perhaps UESL has a smooth muscle origin [5]. Immunohistochemistry showed an over expression of p53 in more than 80% of tumor cells, suggesting that the P53 pathway may plays a role in carcinogenesis of this rare tumor [4]. 

The adult patients with UESL often show some nonspecific symptoms, including epigastric mass, dull upper abdominal pain, and hepatomegaly found on routine physical examination. Standard laboratory tests are often uninformative, as are virus markers of hepatitis, AFP, CEA, and CA199 etc. There is no cirrhosis found in the patients with UESL, suggesting it has no relationship with hepatitis. 

Ultrasonography often reveals cystic mass in the left or right lobe of the liver. CT or MRI is the main method of diagnosis. At cross-sectional imaging, the tumor typically appears as a large (10cm to 25cm in diameter) solitary, predominantly cystic mass with well-defined borders. The cystic appearance is due to the high water content of the myxoid stroma. Therefore, in MRI, large portions of the mass have low signal on T1-weighted images and high signal intensity on T2-weighted images. On contrast-enhanced CT and MRI, enhancement is present in the solid, usually peripheral portions of the mass, especially in delayed images [9,10]. 

Because there are no specific symptoms, tumor marks, or radiographic results, it is usually difficult to make the diagnosis before surgery and specimen pathology. Differential diagnosis includes other cystic lesions in the liver, like simple (bile duct) cyst, polycystic liver disease, biliary hamartoma, Caroli disease, intrahepatic biliary cystadenoma and cystadenocarcinoma, cystic metastases, pyogenic and amebic abscesses, intrahepatic hydatid cyst, extrapancreatic pseudocyst, and intrahepatic hematoma and biloma [9]. 

In children, the prognosis of UESL has been very poor until recently when aggressive preoperative chemotherapy, similar to that used for rhabdomyosarcoma, has permitted more complete tumor resection of initially unresectable disease [11]. Bisogno reported 12 of 17 patients who were alive after a 20 year follow-up [12]. And in adults, Grazi reported one case being alive and disease free for 62 months after the operation [13]. Thus, pre- and/or post-operative systemic chemotherapy (with cisplatin, adriamycin, cyclophosphamide) may improve patients’ survival [12,14]. 

In conclusion, we report here a case of adult primary undifferentiated embryonal sarcoma of the liver. The patient had no specific symptom, and the tumor marks as well as the image results showed no obvious characteristic. The correct diagnosis was established from the pathology result following surgery. It suggests that the correct initial diagnosis of hepatic cystic lesion such as UESL is very difficult. Extensive knowledge of the differential diagnosis, care and consideration should be taken when dealing with cystic lesions of the liver. The complete surgical resection and adjuvant chemotherapy pre- and/or post-operatively may benefit patients with UESL.

Fig 1: Abdominal CT without contrast showed the lesion was predominantly hypodense with a CT value of -15~39 HU.

Fig 2: On dynamic contrast CT of portal vein period, there was a little enhancement of its cystic cavity with a CT value of -9~43 HU.

Fig 3: On contrast CT of delay period, papillary protrusion showed a CT value of 31~75 HU.