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Int J Surg Case Rep
Int J Surg Case Rep
International Journal of Surgery Case Reports
2210-2612
Elsevier

S2210-2612(24)01043-5
10.1016/j.ijscr.2024.110262
110262
Case Report
Unusual gastric localization of an inflammatory myofibroblastic tumor: A case report and review of the literature
Laamiri Ghazi ac
Tormane Mohamed Amine medaminetormane307@gmail.com
ac⁎1
Dougaz Amel bc
Bani Amina bc
Bouassida Mahdi ac
Touinsi Hassen ac
a Department of General Surgery, Hospital Mohamed Taher Maamouri, Nabeul, Tunisia
b Department of Anatomopathology, Hospital Mohamed Taher Maamouri, Nabeul, Tunisia
c University Tunis El Manar, Faculty of Medicine of Tunis, Tunisia
⁎ Corresponding author at: University of Tunis El Manar, Tunisia Department of General Surgery, Hospital Mohamed Taher Maamouri, Nabeul, Tunisia. medaminetormane307@gmail.com
1 Present address: Rue Okbaa Ben Nafaa 5090 Bekalta Monastir – Tunisia.

10 9 2024
10 2024
10 9 2024
123 11026224 6 2024
2 9 2024
6 9 2024
© 2024 The Author(s)
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction and importance

Primary inflammatory myofibroblastic tumor is a rare subgroup of mesenchymal tumors. Gastric localization is extremely rare, and patients may present with abdominal pain and a palpable abdominal mass. Here, we present a case of gastric inflammatory myofibroblastic tumor revealed by abdominal pain, which was treated with wide local excision.

Case presentation

This report illustrates the case of a 55-year-old female who presented with abdominal pain. Imageology and gastrointestinal endoscopy revealed a posterior gastric mass, which was treated with wide local excision. Immunohistochemical analysis of the specimen confirmed the diagnosis of inflammatory myofibroblastic gastric tumor. The patient had an uneventful postoperative course and she remained in remission after 6 months of follow-up.

Discussion

Inflammatory myofibroblastic tumor is a very rare mesenchymal tumor that usually affects children and young adults. Gastric localization is also very rare and does not typically cause specific clinical symptoms.

Surgery is the mainstay of treatment, and resection depends on the size and location of the lesion. The definitive diagnosis is confirmed by immunohistochemical analysis of the specimen.

Conclusion

Myofibroblastic tumor is a rare subgroup of mesenchymal tumor. Gastric localization is an uncommon presentation. Surgery is the mainstay of the treatment. Histological analysis of the surgical specimen is essential for a final diagnosis.

Highlights

• Inflammatory myofibroblastic tumor is a very rare benign lesion which belongs to mesenchymal tumor.

• Gastric localization is uncommon.

• Surgical resection is the only radical treatment.

• Immunohistochemical analysis is crucial for definitive diagnosis.

Keywords

Myofibroblastic tumor
Gastric
Inflammatory
Benign tumors
Case report
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pmc1 Introduction and importance

The primary inflammatory myofibroblastic tumor is a rare subgroup of mesenchymal tumors [1]. It is more common in children and young female patient within the first two decades of life, and is rare after 30 years [2]. These tumors arise from a reactive or post-surgical inflammatory process and usually occur in the lungs, mesentery, omentum, and retroperitoneum, but can also be seen in the genitourinary tract and other organs [3,4]. However, gastric localization is extremely rare, and only 34 cases have been reported in the literature [4,5]. Patients may present with abdominal pain, hematemesis, melena, and a palpable abdominal mass [5]. Herein, we present rare case of a 55-year-old woman with gastric inflammatory myofibroblastic tumor, which was successfully treated with wide local excision.

This work has been reported following the SCARE 2020 criteria [6].

2 Presentation of a case

A 55-year-old female presented with intermittent moderate upper abdominal pain for 2 months and weight loss (30 pounds). She denied other gastrointestinal symptoms such as vomiting, intestinal transit disorders, melena, and hematemesis. The patient was a non-smoker and non-alcoholic with no significant medical or familial history. Physical examination revealed mild abdominal tenderness in the epigastrium but no palpable abdominal mass.

Blood tests, including tumor markers, were all within normal range except for microcytic hypochromic anemia with a hemoglobin level of 10.2 mg/dl. Abdominal CT scan revealed a 4 cm mass arising from the posterior wall of the stomach along its minor curvature (Fig. 1). Upper gastrointestinal endoscopy identified a protruding submucosal tumor approximately 3 cm in size on the posterior wall of the lower gastric body, suggestive of a gastrointestinal stromal tumor (GIST) (Fig. 2). A biopsy of the lesion in the posterior wall of the stomach was taken. Pathological result confirmed moderate chronic non-atrophic inflammation with slight intestinal metaplasia.Fig. 1 CT scan showing the posterior gastric lesion.

Fig. 1

Fig. 2 Upper gastrointestinal endoscopy showing the submucosal tumor in the posterior wall of the lower gastric body.

Fig. 2

Laparotomy was performed, revealing a 3 cm encapsulated tumor on the posterior wall of the stomach with no lymph node enlargement or other lesions identified. The lesion appeared to be a submucosal tumor (SMT) so we opted for wedge resection because it's one of the safest procedures for resection. Distal gastrectomy could be considered excessive for non-malignant tumors.

A wide local excision of the mass with a 1.5 cm margin of normal gastric wall was performed, and the specimen was sent for histological analysis. Post-operative blood tests were normal, the patient had an uneventful postoperative course, diet was allowed on day 3 and she was discharged on day 5 after surgery.

Macroscopically, the specimen was a 2 cm soft solid whitish nodule, well encapsulated, with a smooth, shiny external surface and no gastric mucosal lesions. Microscopic examination revealed the tumor composed of round and spindle-shaped myofibroblastic cells, multiple vascular structures, and dispersed inflammatory cells including plasma cells, lymphoid follicles, lymphocytes, neutrophils, and eosinophils (Fig. 3).Fig. 3 Microscopic image showed round and spindle-shaped myofibroblastic cells in the gastric submucosa (HESX2.5).

Fig. 3

Immunophenotypic and immunohistochemistry analyses were positive for smooth muscle actin (SMA) (Fig. 4) and desmin (Fig. 5), but negative for cytokeratin (CK), CD34 (Fig. 6), CD117 (Fig. 7), DOG1, and anaplastic lymphoma kinase (ALK). Based on these morphological and immunohistochemical features, the diagnosis of inflammatory myofibroblastic tumor without malignant features was established.Fig. 4 Immunohistochemistry showing a positive staining for Smooth Muscle Actin (X10).

Fig. 4

Fig. 5 Immunohistochemistry showing a positive staining for Desmin (X10).

Fig. 5

Fig. 6 Immunohistochemistry showing a negative staining for CD34 (X10).

Fig. 6

Fig. 7 Immunohistochemistry showing negative staining for CD117 (X10).

Fig. 7

The patient remained in remission with good overall performance after 6 months of follow-up.

The sequence of diagnostic procedures and treatments are shown in Table 1.Table 1 The sequence of diagnostic procedures and treatments

Table 1Diagnostic procedures/treatments	Date	
Blood tests	20/11/2023	
Abdominal CT scan	24/11/2023	
Upper gastrointestinal endoscopy + Biopsie	27/11/2023	
Anatomo-pathological analysis	04/12/2023	
Surgical resection	08/12/2023	
Anatomo-pathological analysis of specimen	20/12/2023	

3 Clinical discussion

We report a successful local excision of an inflammatory myofibroblastic tumor (IMT) involving the stomach. The main strength of our work is the timely performance of surgical treatment with an uneventful postoperative course. The main weakness is the inability of radiological and endoscopic investigations to confirm the preoperative diagnosis.

Inflammatory myofibroblastic tumor, also known as inflammatory pseudotumor, is a very rare mesenchymal tumor [7] thought to result from a reactive or post-surgical inflammatory process and considered a neoplasm of intermediate biological potential [1,5]. These tumors typically affect children and young adults with a slight female preponderance and are commonly found in the lungs [7,8]. However, studies indicate they can occur at any age and in various organs such as the liver, bowel wall, spleen, omentum, mesentery, and stomach [5,8,9]. Primary gastric IMT is exceedingly rare and generally lacks specific clinical symptoms [10], though some cases present with abdominal pain, melena, hematemesis, and a palpable abdominal mass [10,11]. In our case, the symptoms were a moderate abdominal pain and weight loss. Additionally, blood tests may reveal hyperleukocytosis, high CRP levels, thrombocytosis, normocytic to microcytic hypochromic anemia, and hypergammaglobulinemia [2,5,12].

The specific etiopathogenesis of these tumors remains unclear, but more than 50 % of extrapulmonary localizations exhibit ALK gene rearrangements on chromosome 2p23. Cytogenetic abnormalities, DNA aneuploidy, clonal chromosome abnormalities, and the role of oncogenic viruses in the pathogenesis of IMT suggest that it is a real neoplasm [13]. Various mechanisms have been proposed for tumor development, including trauma, surgery, autoimmunity, an exaggerated inflammatory response to viral infections such as Epstein-Barr virus, bacterial infections like Escherichia coli and Helicobacter pylori, inflammation following radiochemotherapy, surgery, and steroid use [13,14]. Due to the lack of specific clinical or radiological features, the diagnosis of gastric IMT can only be definitively made through histopathological analysis of the excised specimen [13,14]. Given the histological variability of this tumor, early surgical resection is imperative, ranging from sub-mucosal excision to distal gastrectomy with Roux-en-Y reconstruction [11,14].

Pathological and immunohistochemical analyses are crucial for diagnosing primary gastric myofibroblastic tumors. Histologically, these tumors exhibit epithelioid and/or spindled myofibroblastic proliferation, a myxoid stroma background, and a lymphoplasmacytic infiltrate intermingled with tumor cells [8,9]. Several gastric tumors must be differentiated from IMT, including gastrointestinal stromal tumor (GIST), smooth muscle neoplasm, inflammatory fibroid polyp, fibromatosis, solitary fibrous tumor, and rarely, follicular dendritic cell sarcoma [3,4].

Gastrointestinal stromal tumors may present with cyst formation, hemorrhage or necrosis, occasionally seen in some IMT. GIST does not have the inflammatory background usually found in IMT.

Immunohistochemistry plays a critical role in confirming the diagnosis by ruling out differential diagnoses. Inflammatory myofibroblastic tumors typically stain positive for vimentin, muscle-specific actin, SMA, ALK, and desmin, while they are negative for CD34, S-100, CD117, and estrogen receptor. In contrast, GISTs almost always stain positive for CD117 and DOG1, frequently for CD34, and variably for SMA, but are negative for ALK, desmin, and keratin [4,5].

In our case, immunohistochemistry analyses were positive for smooth muscle actin (SMA) and desmin, but negative for CD34, cytokeratin (CK), CD117, DOG1, and anaplastic lymphoma kinase (ALK).

According to the World Health Organization's updated classification of soft tissue tumors, IMTs are defined as intermediate tumors whose morphological spectrum lies between benign and malignant characteristics. In addition, pathological expression of anaplastic lymphoma kinase (ALK) may be a prognostic indicator of possible local recurrence and metastasis in intra-abdominal IMT [14]. Coffin et al. reported,in a review of the literature, that 13 of 53 patients with gastric myofibroblastic tumors (24.5 %) had a recurrence within two years of treatment [10]. That's why some authors recommend that patients should benefit from a follow-up CT scan and endoscopy [15].

In summary, we present the case of a 55-year-old female with abdominal pain due to gastric inflammatory myofibroblastic tumor suspected by CT scan and gastrointestinal endoscopy, successfully treated with surgical resection. Our case underscores the importance of surgical resection and immunohistochemical analysis of the excised specimen for definitive diagnosis and radical treatment.

4 Conclusion

Inflammatory myofibroblastic tumor is a rare type of mesenchymal tumor, and its occurrence in the stomach is exceedingly rare. Symptoms are typically non-specific, commonly presenting as abdominal pain or a palpable mass. Surgery is the primary treatment approach, which can vary from sub-mucosal excision to distal gastrectomy.

IMT should be taken into account in the differential diagnosis of gastric submucosal tumors, which can contribute to safe and complete resection.

Accurate immunohistochemical assessment aids in distinguishing inflammatory myofibroblastic tumor from other gastric lesions, and the definitive diagnosis is confirmed through histological analysis of the surgical specimen.

Patient consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Ethical approval

Ethical approval for this study is not required. An exemption has been obtained by the ethics committee of the Mohamed Taher Maamouri hospital because the patient's anonymity was respected.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contribution

Mohamed Amine Tormane and Ghazi Laamiri did the conception and design of the work, the data collection, and the data analysis and interpretation.

Amel Dougaz and Amina Bani: did the critical revision of the article.

Mahdi Bouassida and Hassen Touinsi: did the final approval of the version to be published.

All authors read and approved the final manuscript.

Guarantor

Mohamed Amine Tormane.

Ghazi Laamiri.

Research registration number

n/a.

Declaration of competing interest

No conflicts of interest.

Acknowledgements

We want to acknowledge the paramedical team of the surgical department of Mohamed Taher Maamouri Hospital for their continuous efforts.
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