Exophytic cystic gastrointestinal stromal tumor mimics hepatic abscess or tumor

Guisen Lin; Renhua Wu

doi:10.4103/RID.RID_8_21

CASE REPORT

Year : 2022 | Volume : 9 | Issue : 2 | Page : 75-78

Exophytic cystic gastrointestinal stromal tumor mimics hepatic abscess or tumor

Guisen Lin¹, Renhua Wu²
¹ Department of Radiology, The Second Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
² Department of Radiology, The Second Affiliated Hospital of Shantou University Medical College; Provincial Laboratory for Breast Cancer Diagnosis and Treatment, Shantou, Guangdong, China

Date of Submission	28-Sep-2021
Date of Acceptance	18-Jun-2022
Date of Web Publication	8-Nov-2022

Correspondence Address:
Renhua Wu
Department of Radiology, The Second Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong
China

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/RID.RID_8_21

Abstract

A middle-aged patient presented with epigastric pain, elevated white blood cell count, and mild anemia. Computed tomography (CT) revealed an exophytic gastric mass that mimicked a hepatic abscess or tumor, with intraperitoneal hemorrhage. The mass had heterogeneous texture, interstitial bleeding, and cystic change that showed delayed mild enhancement on multiphase CT. This was consistent with gastrointestinal stromal tumor that was confirmed by pathological and immunohistochemical analysis.

Keywords: Computed tomography, gastrointestinal stromal tumor, hepatic abscess, hepatic tumor

How to cite this article:
Lin G, Wu R. Exophytic cystic gastrointestinal stromal tumor mimics hepatic abscess or tumor. Radiol Infect Dis 2022;9:75-8

How to cite this URL:
Lin G, Wu R. Exophytic cystic gastrointestinal stromal tumor mimics hepatic abscess or tumor. Radiol Infect Dis [serial online] 2022 [cited 2023 Mar 23];9:75-8. Available from: http://www.ridiseases.org/text.asp?2022/9/2/75/360506

Introduction

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. Most GISTs present as exophytic or intramural masses with various imaging manifestations. Usually, small GISTs have a homogeneous texture with mild-to-moderate enhancement. In contrast, large GISTs show heterogeneous texture or enhancement because they tend to be combined with necrosis, cystic change, or hemorrhage. Complete cystic change of GIST is rare, and the diagnosis can be difficult. Here, we report a case of exophytic, cystic GIST that mimicked a hepatic abscess or tumor.

Case Report

A 50-year-old woman without a significant medical history developed dull epigastric pain on waking in the morning, which developed into searing pain 2 h later. She was taken to the local hospital, where abdominal computed tomography (CT) was performed, and the findings were abnormal. The patient was transferred to the emergency department of our hospital. Her physical examination was otherwise unremarkable except for mild epigastric tenderness without a rebound. Her laboratory studies showed an elevated white blood cell count of 13.5 × 10⁹/L (reference range, 3.5 × 10⁹–9.5 × 10⁹/L) and decreased hemoglobin of 103 g/L (reference range, 115–150 g/L). Her carcinoembryonic antigen, α-fetal protein, and carbohydrate antigen (CA) 125, CA 19–9, and CA 15–3 were all within normal limits. CT was performed in our radiology department and contrast-enhanced images were obtained 3 days later.

CT of the upper abdomen revealed a hypodense mass (6.5 cm × 4.8 cm × 4.2 cm) with a relatively irregular capsule [Figure 1]. Bleeding inside the mass and perihepatic hematoma was noted. On both the axial and coronal views, the mass was close to the left border of the liver and lesser curvature of the stomach [Figure 1] and [Figure 2]. Contrast-enhanced images obtained 3 days later revealed delayed, mild heterogeneous enhancement. However, most of the mass was not enhanced. Compared with the CT imaging without contrast 3 days before, there was clear separation between the mass and the liver on the lower axial view, which was not detected in previous noncontrast images. Perihepatic effusion disappeared and perisplenic effusion was observed at this time [Figure 3].

Figure 1: Abdominal axial CT without contrast at different levels (a-c, from upper level to lower level) showed ahypodense mass (6.5 cm × 4.8 cm × 4.2 cm) with an irregular capsule, withbleeding inside the mass and perihepatic hematoma. CT: Computed tomography

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Figure 2: Abdominal coronal CT without contrastat different levels (a-c, from front to back). The mass was closely attachedto the left border of the liver and lesser curvature of the stomach. CT: Computed tomography

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Figure 3: Contrast-enhanced images obtained 3 days later show mild heterogeneous enhancement with most of the mass unenhanced ([a] arterial phase, [b] portal phase, [c] equilibrium phase)

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Discussion

The most difficult part of the radiological diagnosis of GIST was defining the location of the mass. It seemed initially that the lesion arose from the left lobe of the liver as an exophytic mass. Differential diagnoses included hepatic abscess, exophytic hepatocellular adenoma (HCA) with bleeding into the abdomen and ruptured hepatocellular carcinoma. Hepatic abscess was initially suspected by noncontrast-enhanced CT, in combination with the elevated white blood cell count. However, the patient presented without fever and the typical peripheral enhancement was not observed after contrast injection. Hepatocellular carcinoma was less suspected because the mass showed no enhancement in the arterial phase. In addition, the patient did not have cirrhosis and her α-fetal protein level was not elevated. HCA is a rare benign tumor with increased risk in patients who use oral contraceptives, which were not used by this patient. Even though some HCAs appear hypoattenuating with hyperattenuating bleeding inside on unenhanced CT scan,^[1] as in the present case, most well-defined HCAs would be expected to appear hyperintense in the early arterial phase with delayed washout.^[1]

Careful imaging analysis suggested that the mass could have arisen from the stomach. On both unenhanced and enhanced images, the lesion was attached to the lesser curvature of the stomach. In addition, the mass seemed to be detached from the liver, with a greater free edge in the axial view of the enhanced image. The differential diagnoses of an exogastric mass include GIST, schwannoma, and inflammatory myofibroblastic tumor (IMFT). Schwannomas are uncommon neoplasms of the gastrointestinal tract. The presence of low-attenuation hemorrhage is not the typical finding of schwannomas, and the lack of hemorrhage, necrosis, and degeneration can distinguish them from stromal tumors.^[2],[3] The CT appearance of IMFT is nonspecific and it can present as a hypodense to isodense mass with variable to no enhancement.^[4] However, bleeding is rare for IMFT, and to our knowledge, IMFT combined with bleeding into the abdomen has not been reported. Therefore, in the present case, the presence of exophytic hypodense mass with hemorrhage and central cystic change suggested the diagnosis of GIST.

Exploratory laparotomy revealed a mass protruding from the lesser curvature of the stomach with blood in the peritoneal cavity. No active bleeding was found and the mass was resected without difficulty. The final pathological diagnosis confirmed with immunohistochemistry was GIST (7.5 cm × 5.0 cm × 2.5 cm) with interstitial hemorrhage [Figure 4].

Figure 4: (a) Pathologic specimen shows sheet of spindle cells with interstitial bleeding. (b) Immunohistochemistry study reveals the tumor cells are CD117, CD34 and DOG-1 positive as well as focal Desmin and NSE positive which is consistent with stromal tumor

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GISTs are rare neoplasms that account for 1%–3% of all gastrointestinal malignancies.^[5] However, they are the most common mesenchymal tumors of the gastrointestinal tract, with 60%–70% arising in the stomach. GISTs were previously referred to as leiomyomas, leiomyoblastomas, or leiomyosarcomas, but they are now thought to be derived from stem cell precursors of the interstitial cells of Cajal.^[6] The most common and well-known mutation for GISTs is KIT, a growth factor receptor tyrosine kinase.^[7] This discovery was important because the development of imatinib, a tyrosine kinase inhibitor, as the first breakthrough in the treatment of GISTs was based on it.^[8],[9]

Clinical presentation of patients with GISTs varies depending on the location and size of the tumors. Small GISTs are usually asymptomatic and found incidentally. Clinical manifestations of patients with large and symptomatic GISTs are nonspecific, including fatigue, nausea, anorexia, abdominal pain, fever, and weight loss.^[10] Gastrointestinal bleeding or tumor rupture with intraperitoneal hemorrhage can occur with mucosal ulceration. In the present case, the patient presented with sudden worsening of abdominal pain, mild anemia, and elevated white blood cell count, which were correlated with recurrent intratumoral bleeding and infection.

Most gastric GISTs present as exophytic or intramural masses with varied imaging manifestations relative to their size. Small GISTs usually have a homogeneous texture with mild-to-moderate enhancement. On the contrary, large GISTs often appear with heterogeneous texture or enhancement because they tend to be combined with necrosis, cystic change, or hemorrhage.^[11] The causes of cystic GISTs include:^[1] primary cystic GISTs with cystic structure comprising a large proportion,^[2] malignant GISTs with rapid growth rate and subsequent necrosis leading to cystic change,^[3] metastatic lesions that are cystic in nature, and^[4] GISTs treated with imatinib.^[12],[13] Each type of cystic gastrointestinal mesenchymal tumor has a more specific imaging presentation. However, the present case is exceptional and GISTs with totally cystic change have not been reported.

Surgical management, including open, laparoscopic, and robot-assisted surgery, remains the current standard treatment for GISTs. In addition, imatinib treatment of advanced GISTs has been proven to improve long-term survival. Imatinib is also indicated as preoperative neoadjuvant therapy to reduce tumor size, and as adjuvant therapy for patients after complete resection of the mass but with a high rate of recurrence.^[8],[14]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgments

We thank Cathel Kerr, BSc, Ph.D., from Liwen Bianji (Edanz) (www.liwenbianji.cn), for editing the English text of a draft of this manuscript.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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