Laparoscopically Resected Ectopic Hepatocellular Carcinoma Mimicking Subepithelial Tumor of Stomach: A Case Report

Abstract

Ectopic hepatocellular carcinoma (HCC) can be defined as an HCC arising from hepatic parenchyma located in an extrahepatic organ or tissue. Fewer than 100 cases of ectopic liver have been reported. In 30 of these cases, HCC was detected in ectopic tissue. The author describes a case of ectopic HCC mimicking subepithelial tumor (SET) of the stomach successfully treated by laparoscopic resection. This case report also provides a pertinent review of the literature. A 61-year-old male was referred to our department for the management of an intra-abdominal mass found on abdominal computed tomography performed at a local medical center due to a 2-month history of vague abdominal pain. Abdominal magnetic resonance imaging and computed tomography showed a 7.2-cm sized heterogenous mass over the left subphrenic space adjacent to the stomach. Esophagogastroduodenoscopy showed a huge subepithelial mass at the fundus of the stomach. Based on the above findings, the diagnosis of SET of the stomach such as gastrointestinal stromal tumor or leiomyoma was suspected. Laparoscopic surgery was performed for definite diagnosis and treatment of the huge SET of the stomach. Histologic diagnosis was ectopic HCC of the trabecular type. Its histologic grade was consistent with Edmondson grade II. Although ectopic HCC is quite rare tumor of the stomach, it should be considered in the differential diagnosis of other abdominal mass-like lesions. Currently, with advances of laparoscopic surgery, laparoscopic resection for complete excision of ectopic HCC is possible with acceptable results.

Introduction

Ectopic liver is a rare entity defined as the presence of normal liver parenchyma separated from the liver due to aberrant migration of the hepatic tissue during embryological development. The incidence of ectopic liver has been reported to be between 0.24% and 0.47% [1–3]. Due to small sizes of most ectopic livers, lack of awareness of this unusual condition among radiologists, difficulty interpreting the image, and frequent lack of symptoms, it is difficult to detect ectopic liver tissue before surgical intervention or autopsies.

Hepatocellular carcinoma (HCC) is a type of cancer that originates from the hepatocyte. It typically develops from normal liver tissue. It is also associated with chronic liver diseases such as hepatitis B, hepatitis C, or cirrhosis caused by other reasons. Ectopic HCC can be defined as an HCC arising from hepatic parenchyma located in an extrahepatic organ or tissue. Fewer than 100 cases of ectopic liver have been reported. In 30 of these cases, HCC was detected in ectopic tissue [4–9].

The author describes a case of a male patient with HCC arising from ectopic liver tissue mimicking gastric GIST successfully treated using a laparoscopic approach. This case report also provides a pertinent review of the literature.

Case Presentation

A 61-year-old male patient was referred to our department for the management of an intra-abdominal mass, which was found on abdominal computed tomography (CT) performed at a local medical center due to a 2-month history of vague abdominal pain. He was not taking mediation or abusing alcohol. There was no medical history such as hepatitis B or C or surgical history. His vital signs were stable. There were no symptoms such as nausea, vomiting, or diarrhea except for intermittent, vague abdominal pain. Physical examination revealed no palpable mass on the left upper abdomen. There was no tenderness or rebound tenderness. Laboratory values including α-fetoprotein (AFP) and carbohydrate antigen 19-9 were within their normal ranges except for an elevated level of protein induced by vitamin K absence or antagonist-II (PIVKA-II) at 83.99 mAU/mL. Abdominal enhanced magnetic resonance imaging and contrast-enhanced CT at the portal venous phase of the abdomen showed a 7.2-cm sized heterogenous enhancing exophytic mass over the left subphrenic space adjacent to the stomach (shown in Fig. 1a, b). Esophagogastroduodenoscopy showed a huge subepithelial mass at the fundus of the stomach. Based on the above findings, a diagnosis of subepithelial tumor of the stomach such as GIST or leiomyoma was suspected. Laparoscopic surgery was performed for definite diagnosis and treatment of the huge subepithelial tumor of the stomach.

Fig. 1.

Enhanced magnetic resonance imaging (a) and contrast-enhanced helical CT scan (b) at the portal venous phase of the abdomen showing a large, lobulating, contoured heterogeneous enhancing exophytic soft tissue mass, measuring 7.2 cm, over the subphrenic space adjacent to the stomach.

At surgery, a 4-trocar technique was employed. First, one 11-mm trocar was placed at the umbilicus as a camera port. After establishing pneumoperitoneum, a 12-mm and a 5-mm trocar were placed at the upper lateral border of the right rectus muscle under laparoscopic vision. One more 5-mm trocar was then placed at the left upper abdomen, just below the rib cage. At first glance, before lifting the left lobe of the liver, there was no hepatic lesion with the stomach looking normal. After lifting the left lobe of the liver and the right downward traction of the stomach, the upper part of stomach and the left subphrenic area were visualized, and a well-circumscribed mass of the stomach compressing the spleen was found. The suspected tumor-feeding vessel was ligated using a Hem-o-lock ligating clip^Ⓡ. The tumor including part of the stomach was then resected using a stapler. Upon resection, the tumor was a gray or yellow-to-brown solid tumor contained within a thin fibrous capsule (shown in Fig. 2). The size of the resected specimen was 7.3 cm × 6.8 cm × 4.5 cm. It was sent to the pathology department for microscopic examination.

Fig. 2.

Gross specimen showed a soft and well-circumscribed tissue mass measuring 7.3 cm × 6.8 cm × 4.5 cm. There are linear stapling clip at the resecting surface from the stomach (arrow head) and Hem-o-lock ligating clip^Ⓡ at the feeding vessel (arrow).

The pathologic result showed that the tumor was composed of large polygonal cells arranged in a trabecular pattern separated by sinusoid-like blood spaces. Tumor cells had hyperchromatic nuclei with prominent nucleoli and abundant eosinophilic cytoplasm (shown in Fig. 3). The histologic diagnosis was an ectopic HCC of the trabecular type. Its histologic grade was consistent with Edmondson grade II. After laparoscopic wedge resection, the patient recovered without any complications such as bleeding, leakage, or infection. He was discharged on the 9th day. After the operation, there was a little pain in the wound area, but it improved and there was no more vague abdominal pain like before the operation.

Fig. 3.

Microscopically, the tumor was composed of large polygonal cells arranged in a trabecular pattern separated by sinusoid-like blood spaces. a Tumor cells had enlarged and hyperchromatic nuclei with prominent nucleoli and abundant eosinophilic cytoplasm (H&E stain, ×100). Immunohistochemical staining of the tumor showed capillarization of the sinusoidal vessels (CD34 stain, ×100) (b), and strong and diffuse granular cytoplasmic staining (Hep Par 1 statin, ×100) (c). The histologic diagnosis was ectopic HCC of the trabecular type. Its histologic grade was consistent with Edmondson grade II. Nuclei are enlarged and hyperchromatic.

One month after surgery, follow-up tests were performed in the outpatient clinic. They showed normal results. Follow-up tests were performed at 6 and 12 months after surgery, including liver ultrasonography, AFP, PIVKA-II measurements, and contrast-enhanced helical CT. The level of serum PIVKA-II dropped to normal (27.30 mAU/mL). No signs of recurrence were observed. Timeline from symptoms to examinations, diagnosis, surgery, and follow-up test after discharge is shown in Figure 4. In this case, laparoscopic resection for ectopic HCC of the stomach was safe and reliable.

Fig. 4.

Timeline from symptoms to examinations, diagnosis, surgery, and follow-up test after discharge. LMC, local medical center; CT, computed tomography; MRI, magnetic resonance imaging; HCC, hepatocellular carcinoma; USG, ultrasonography; AFP, α-fetoprotein; PIVKA-II, protein induced by vitamin K absence or antagonist-II.

Discussion

Hepatic tissue located in an abnormal position due to embryological anomalies is very rare. It is mainly found during laparoscopy, laparotomy, or autopsy. It has been found in about 0.7% of laparoscopic surgeries [10]. Although abnormally positioned liver tissue is rare, it can occasionally cause clinical symptoms.

Collan et al. have described four main types of abnormally positioned livers, including (a) accessory liver lobe that can reach a considerable size and is attached to the liver by a stalk; (b) small accessory liver lobe attached to the liver that is usually small, about 10–30 g in weight; (c) ectopic liver situated outside the liver without any connection with it that is usually attached to the gallbladder or intra-abdominal ligaments; and (d) microscopic ectopic liver found occasionally in the wall of the gallbladder [11]. Some researchers have also classified them into ectopic liver, caused by embryonic developmental displacement of liver tissue, and pedunculated liver, caused by hypertrophy of one or more hepatic cords [12]. This HCC arising from ectopic liver tissue located in abnormal positions experienced by the author can be classified as an ectopic liver (hepatocellular) carcinoma. Ectopic HCC is a very rare disease. After author searched “ectopic hepatocellular carcinoma” in PubMed, 24 case reports in full text were available [13].

HCC that arises from an orthotopic liver after hepatitis B or C virus infection accounts for about 80% of all HCC cases. The incidence of concomitant liver cirrhosis has been reported to be 69.3–81.3% [14, 15]. Only 7 (31%) of 22 cases of ectopic HCC were associated with maternal liver cirrhosis, suggesting a different carcinogenesis pathway from that of HCC arising in the orthotopic liver [1]. In this rare case, ectopic liver cell carcinoma that they encountered occurred in the absence of a history of liver disease such as maternal liver viral hepatitis or cirrhosis and progressed from ectopic liver tissue to HCC. Therefore, it is thought that ectopic HCC differs from liver cell carcinoma that occurs in the normal location. An ectopic HCC is known to occur due to biliary obstruction and vascular insufficiency of the ectopic liver tissue, independent of viral hepatitis or liver cirrhosis [13].

Although ectopic livers have completely functional architecture, they might be metabolically handicapped. This may facilitate carcinogenesis. Ectopic liver tissue also has increased neoplastic potential compared to orthotopic liver tissue. This might have given rise to the hypothesis that ectopic livers are particularly predisposed to the development of HCC. The level of PIVKA-II was significantly increased in the serum of HCC patients. It could serve as a new serum marker for HCC [16]. Some researchers believe that this increase of PIVKA-II level may be due to abnormal enzymes related to vitamin K metabolism generated during malignant transformation of hepatocytes [17]. For this reason, PIVKA-II was valuable for the diagnosis of AFP-negative HCC. It can be used as a supplement of AFP in the diagnosis of HCC. Combining two markers greatly improved the diagnostic efficiency of HCC. Serum PIVKA-II might be used as an indicator for evaluating the curative effects of HCC surgery [18]. In this rare case, increased preoperative PIVKA-II levels had fallen to normal levels after operation, meaning a curative surgery and a better prognosis.

Ectopic HCC has an excellent therapeutic outcome with complete resection alone as the possibility of tumor development is confined to the ectopic liver. Generally, it is also well located with structures that make them amenable to laparoscopic resection. Therefore, curative surgery with en-bloc resection seems possible. Ectopic HCC experienced by the author also showed no recurrence or elevation of AFP or PIVKA-II in follow-up tests for 1 year after surgery, indicating that it could arise without pre-existing liver disease in normal hepatic parenchymal tissues with excellent therapeutic outcomes after surgical resection alone due to its unique anatomical characteristics of being located solely.

In conclusion, although ectopic HCC is a quite rare tumor of the stomach, mimicking gastric GIST, it should be considered in the differential diagnosis of other abdominal mass-like lesions. Currently, with advances in laparoscopic surgery, laparoscopic resection for complete excision of ectopic HCC without complications is possible and capable of producing acceptable results. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material (for all online suppl. material, see https://doi.org/10.1159/000531842).

Statement of Ethics

This study was approved by the Institutional Review Board of the Yeungnam University Medical Center in Daegu, Republic of Korea (IRB No. YUMC-2023-04-009). Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

Conflict of Interest Statement

The author has no conflicts of interest to declare.

Funding Sources

There is no funding source.

Author Contributions

Yong-Eun Park collected data, wrote the manuscript, designed the figures, and reviewed the manuscript.

Funding Statement

There is no funding source.

Data Availability Statement

Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study. All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.