A rare case of splenunculus buried within the stomach

Mazen Farhat¹, Karam Karam², Philippe Attieh³, Elie Mina⁴, Zarouhie Meguerian^1,4, Elias Fiani^1,2, Ihab I. El Hajj^1,2

¹ Department of Gastroenterology and Hepatology, St George University of Beirut, Beirut, Lebanon

² Department of Gastroenterology and Hepatology, University of Balamand, Beirut, Lebanon

³ Department of General Surgery, University of Balamand, Beirut, Lebanon

⁴ Department of Pathology, St George University of Beirut, Beirut, Lebanon

Corresponding author’s e-mail: ihabelhajj@hotmail.com

Received: 07/11/2025
Accepted: 17/11/2025
Published: 19/12/2025

Conflicts of Interests: The Authors declare that there are no competing interests.
Patient Consent: Signed informed consent for the publication of this case was obtained from the patient prior to writing the manuscript.
This article is licensed under a Commons Attribution Non-Commercial 4.0 License

How to cite this article: Farhat M, Karam K, Attieh P, Mina E, Meguerian Z, Fiani E, El Hajj II. A rare case of splenunculus buried within the stomach. EJCRIM 2025;12:doi:10.12890/2025_005988

ABSTRACT

Background: Accessory spleen, or splenunculus, is a congenital anomaly resulting from failure of splenic anlage fusion during embryonic development. It is most commonly located near the splenic hilum or pancreatic tail and rarely occurs within the stomach wall. Gastric accessory spleen is a rare entity that may mimic submucosal neoplasms such as gastrointestinal stromal tumour, posing a diagnostic challenge.
Case presentation: We report the case of a 37-year-old male presenting with a 3-month history of epigastric pain, dyspepsia, and nausea. Endoscopy revealed a 2.5–3 cm submucosal mass in the gastric fundus with intact mucosa, and erosive antral gastritis. Endoscopic ultrasound demonstrated a 22.6 × 17.2 × 23.3 mm hypoechoic, homogeneous lesion arising from the third layer of the gastric wall. Endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) showed lymphoid aggregates with characteristic vascular structures lined by CD8-positive littoral cells and CD68/PGM1-positive macrophages. Immunohistochemistry excluded epithelial, neuroendocrine, and lymphoproliferative neoplasms, confirming the diagnosis of gastric accessory spleen.
Discussion: This case is distinctive because the patient had no prior splenectomy or trauma and was diagnosed preoperatively using EUS-guided biopsy—avoiding unnecessary surgery. Gastric accessory spleen remains a rare but important differential diagnosis for submucosal gastric lesions. Recognition of its imaging and histopathologic features can prevent misdiagnosis and overtreatment.
Conclusion: Gastric accessory spleen is a benign, rare condition that should be considered in patients presenting with gastric submucosal masses. Non-invasive diagnostic modalities such as EUS-FNB and immunohistochemistry are essential to achieve an accurate diagnosis and to avoid unnecessary surgical resection.

KEYWORDS

Stomach, fundus, submucosal mass, EUS, accessory liver

LEARNING POINTS

• Gastric accessory spleen is a rare, usually incidental finding with no clinical significance.
• It should be considered as one of the differential diagnoses of gastric subepithelial lesions.
• Despite the fact that histopathologic evaluation remains the gold standard, both nuclear scintigraphy and enhanced computed tomography scan may be useful in the diagnosis of ectopic splenic tissue.

INTRODUCTION

The spleen is a lymphoid vascular organ located in the left upper quadrant of the peritoneal cavity^[1]. It functions as a filter that eliminates old blood cells, and it is essential for the production and storage of immune cells, and the defence against foreign organisms^[2].

Splenic tissue located outside of the regular spleen is known as an accessory spleen, splenule, or splenunculus. The majority of accessory spleens (75%) are found close to the splenic hilum and (17%) around the pancreatic tail. However, they can also be located within the gastrointestinal tract^[1]. Splenules are most likely the result of mesenchymal buds that fail to fuse in the dorsal mesogastrium during the 5^th week of the embryonic life. Approximately 10-30% of people worldwide are born with this congenital defect^[2]. The majority are benign and are discovered incidentally on cross-sectional abdominal imaging or during endoscopy^[1].

The current case highlights the diagnostic challenge due to an accessory spleen manifesting as a submucosal gastric mass.

CASE DESCRIPTION

A 37-year-old male patient presented with 3-month history of epigastric pain, dyspepsia, and nausea. Abdominal ultrasound showed normal liver and spleen, and a normal gallbladder with no stones or sludge. Blood work including a complete blood count and liver enzymes was normal. Upper endoscopy showed a large 2.5 to 3 cm submucosal mass in the gastric fundus with normal overlying mucosa on white light and narrow band imaging (NBI), and few dispersed superficial erosions in the gastric antrum and pre-pyloric area (Fig. 1A and 1B). Antral biopsies showed mild Helicobacter pylori positive erosive gastritis for which the patient received eradication therapy. Upper endoscopic ultrasound (EUS) of the submucosal lesion showed a 22.6 × 17.2 × 23.3 hypoechoic and homogenous lesion with irregular borders arising from layer 3 of the gastric wall (Fig. 1C). EUS-guided fine needle biopsy (EUS-FNB) was performed. Histology showed scattered lymphocytic aggregates made of a mixture of small B- and T-lymphocytes separated by sieve like vascular structures lined by round cells with numerous red blood cells, neutrophils and eosinophils (Fig. 2A). These vascular structures are lined by CD8 positive splenic littoral cells and cuffed by CD68/PGM1 positive macrophages. After ruling out epithelial, neuroendocrine, Langerhans cell histiocytic neoplasms as well as lymphoproliferative processes by extensive immunostaining, the overall histologic appearance was compatible with gastric accessory or ectopic spleen. Here is the summary of the immunohistochemical staining results: cytokeratin (-), synaptophysin (-), chromogranin (-), CD117 (-), CD30 (-), S100 (-), CD1a (-), CD20 (+), CD3 (+), myeloperoxidase (+), CD34 (+), CD68/PGM 1 (+) (Fig. 2B), CD31 (+), CD8 (+) (Fig. 2C).

DISCUSSION

We report the case of a benign gastric accessory spleen located in the fundus of the stomach in a patient without any medical or surgical history. The real incidence and prevalence of this condition are not well known, and it is considered a rare incidental finding especially in patients who undergo upper endoscopy for investigation of various upper gastrointestinal complaints such as dyspepsia or before bariatric surgery evaluation^[3].

Although they are usually asymptomatic, patients with gastric accessory spleen may complain of upper abdominal pain and may, in rare cases, suffer from complications such as bleeding, spontaneous rupture, embolization, and torsion^[1].

According to the current literature, accessory spleen is rarely found in the stomach and is mainly located in the splenic hilum and the tail of the pancreas. A total of 12 documented cases of gastric splenule have been reported including 5 females and 7 males, with a female/male ratio of 0.71/1. The mean age of the patients was between 30 and 70 years^[4].

Most masses are located in the gastric fundus. They are well-demarcated, ovoid with smooth surfaces, and their size range from 1–3 cm in diameter. Masses larger than 4 cm are very rare. These lesions can be misdiagnosed as either benign masses like gastric stromal tumour (GIST), leiomyoma, or schwannoma or malignant tumours like lymphoma, neuroendocrine or metastatic deposits^[1,4].

Abdominal cross-sectional imaging: computed tomography (CT) scan and magnetic resonance imaging are pivotal for the diagnosis of gastric splenules. They appear as distinct, single or multiple, round-ovoid masses that are less than 2 cm and show uniform enhancement that is the same as that of normal splenic parenchyma. EUS is superior to computed tomography (CT) scan for differentiating between a submucosal mass and an extrinsic compression lesion of the stomach. However, histopathological confirmation through postoperative specimens or through EUS-FNB is essential for a definitive diagnosis when imaging is inconsistent^[5].

Furthermore, nuclear medicine imaging can also validate the diagnosis. A simple technique that is sensitive and specific for identifying heterotopic splenic tissues is the 99mTc-labeled heat-denatured red blood cell spleen scintigraphy which can distinguish between GIST and accessory spleen^[5].

Since most of the gastric accessory spleens are small and asymptomatic, surgery is not recommended^[2]. However surgical intervention is indicated when there is torsion, bleeding or compressive symptoms^[4]. Surgical excision is reserved for symptomatic cases or when the lesion’s nature remains uncertain after non-invasive evaluation^[6,7]. Importantly, accessory spleens should always be actively looked for during splenectomy, as failure to identify and remove them may result in persistence or recurrence of hematologic diseases (e.g., idiopathic thrombocytopenic purpura) for which splenectomy was performed^[8,9].

Several cases of gastric accessory spleens have been reported in the literature. Table 1 summarizes the different characteristics of the reported cases and compares them to our case.

What makes our case particularly unique is that the patient had no prior splenectomy, trauma, or underlying systemic disease, yet presented with a relatively large (≈3 cm) intramural accessory spleen located in the gastric fundus—an extremely rare presentation. Most previously reported cases occurred in post-splenectomy patients or were incidentally discovered during unrelated surgeries or imaging studies. Furthermore, the diagnosis in our case was achieved preoperatively through EUS-FNB and confirmed by a comprehensive panel of immunohistochemical stains, avoiding unnecessary surgical intervention. This combination of atypical location, absence of prior splenic surgery, and definitive minimally invasive diagnosis highlights the distinctiveness and clinical relevance of our report, emphasizing the importance of considering accessory spleen in the differential diagnosis of gastric submucosal lesions.

CONCLUSION

Gastric accessory spleen is a rare entity. It is usually an incidental finding with no clinical significance. It should be considered as one of the differential diagnoses of gastric sub-epithelial lesions. Despite the fact that histopathologic evaluation remains the gold standard, both nuclear scintigraphy and enhanced CT scan may be useful in the diagnosis of ectopic splenic tissue.