Tplenosis refers to the ectopic, autoimplantation of splenic tissue remnants, usually following trauma or abdominal surgery. These splenic tissue remnants may grow into functional splenic tissue, with distinct red and white pulp and germinal centers.¹ They obtain their blood supply and nutrients by imbibition. Implants are often multiple and range in size from a few millimeters to several centimeters. The first human case was reported in 1910, following an autopsy on a patient with a documented history of splenectomy resulting from trauma.² 

The use of nuclear liver-spleen scanning with technetium Tc 99m sulfur colloid indicates that splenosis occurs in 26% to 59% of postsplenectomy patients.^3,4 We present a case of splenosis in a 55-year-old man, which caused upper gastrointestinal (GI) bleeding.

Case report
A 55-year-old man with a medical history of chronic obstructive pulmonary disease, chronic anemia, and a trauma-related splenectomy 7 years earlier presented to an outside institution because of upper GI bleeding. His initial workup included esophagoduodenoscopy (EGD), which revealed Mallory-Weiss syndrome but no evidence of active bleeding. With no further documented episodes of hematemesis during his initial hospital course, the patient was discharged in stable condition.

The patient later returned, after experiencing melena and recurrent episodes of hematemesis. He required 6 units of packed red blood cell transfusions and was subsequently transferred to our hospital for further care. Of significance, the patient had recently undergone upper and lower GI contrast studies, EGD, and colonoscopy to investigate chronic anemia. The workup had not localized any lesions. 

On physical examination, the patient was observed to be thin, with an easily reducible incisional hernia, no organomegaly, and a soft, nondistended abdomen. A repeat EGD found old blood but no sign of active bleeding. There was the suggestion of a submucosal mass in the gastric fundus; subsequent biopsies of this region were negative for malignancy. Further investigation with endoscopic ultrasonography showed obliteration of the gastric wall layers, which is indicative of an infiltrative or inflammatory process. A 5.2 x 2.8-cm mass was identified on ultrasonography, with multiple nodules measuring approximately 10 mm along the celiac axis.

An abdominal computed tomography (CT) scan indicated the presence of two splenic artery pseudoaneurysms adjacent to the posterior gastric wall (Figure 1). Visceral angiography did not reveal splenic pseudoaneurysms as initially suggested by our radiologists.  

Exploratory laparotomy was performed because of the patient’s persistent upper GI bleeding, the suspicion of malignancy, and the inability to establish a definitive diagnosis. Intraoperatively, the patient was noted to have a ventral hernia and extensive adhesions. The liver was mobilized, and there were multiple soft, enlarged celiac and periportal nodes. Frozen sections of these lymph nodes did not indicate malignancy. Gross examination of the stomach found no distinctly palpable mass, but the stomach was noted to be densely adherent posteriorly. The gastrocolic omentum was then opened to gain access to the lesser space. The posterior wall of the stomach was freed from the posterior abdominal wall, exposing a 6-cm mass within the posterior wall of the fundus. A wide local excision was performed, and the stomach was closed primarily, creating a new gastric tube proximally while preserving the distal stomach. The official pathology report concerning the gastric specimen reported submucosal nodular splenosis (Figure 2).

Discussion
Implantation of splenic tissue remnants can occur anywhere within the abdominal cavity. Splenic tissue has been reported on the mesentery, the serosal surface of the large and small bowel, the greater omentum, the parietal peritoneum, and the peritoneal surface of the diaphragm. Less commonly, it has been reported in extraperitoneal locations, such as in subcutaneous tissues or the thoracic cavity. Implantations at such locations likely result from trauma-related compromise of the abdominal cavity, allowing for extraperitoneal seeding.⁵

CT scanning may show one or more homogeneous, solid, well-circumscribed, noncalcified soft-tissue nodules of variable shapes. Implants are closely related to the tissue at the site of attachment and may demonstrate poor margination. They enhance considerably, however, with the use of intravenous contrast. It is understandable how they could be misinterpreted as splenic artery pseudoaneurysms in the case we describe. Magnetic resonance imaging using supramagnetic iron oxide particles may help show the presence of functional splenic tissue, as can scintillography with indium In 111-labeled platelets, technetium Tc 99m sulfur colloid, or technetium Tc 99m-labeled heat-denatured red blood cells.⁶ The use of these imaging modalities in the present case could have suggested the diagnosis preoperatively.

The clinical significance of splenosis is related to its implantation site. Most commonly, splenosis is an incidental finding on imaging studies or at laparotomy in patients with abdominal pain. Pain related to splenic nodules may be due to a twisted pedicle or a functional lymphoid tissue response to infection.  

Splenosis is a rare cause of GI bleeding, although splenosis may cause chronic GI bleeding related to small bowel intussusception or as a consequence of mucosal erosions from small and large bowel implants.^7,8 Similarly, splenosis may implant within the wall of the stomach, resulting in GI bleeding or the appearance of an intramural mass. The specific cause for bleeding is gastritis or superficial ulceration of the overlying mucosa.

A literature review found four cases of splenosis that caused the appearance of a gastric mass. Two cases were associated with superficial ulcerations.^9-12 Three of the four reported cases required resection for histologic confirmation, while in one case, the diagnosis was established using a technetium Tc 99m sulfur colloid radionuclide scan. Ours was a rare case of splenosis, which caused recurrent episodes of massive gastric bleeding and required   operative resection. Had the diagnosis been entertained or established preoperatively using radionuclide scanning, the operative procedure may have been more straightforward.

Conclusion
Splenosis is the autotransplantation of splenic tissue, which can follow surgery or trauma. Splenosis is usually an incidental finding. In our case, a 55-year-old man with recurrent upper GI bleeding and anemia secondary to intramural gastric splenosis required operative intervention to achieve hemostasis. Splenosis should be entertained in the differential diagnosis of patients who have an unexplained gastric mass and associated GI hemorrhage along with a history of splenectomy or splenic trauma. 

References
1. Hathaway JM, Harley RA, Self S, et al. Immunological function in post-traumatic splenosis. Clin Immunol Immunopathol. 1995; 74(2):143-150.

2. Von Kuttner H. Diskussion: Mizentirpation und ruentgenbehandlung bei leukamie. Berl Klin Wochenschr. 1910;47:1520.

3. Pearson HA, Johnston D, Smith KA, et al. The born-again spleen. Return of splenic function after splenectomy for trauma. N Engl J Med. 1978;298(25): 1389-1392.

4. Livingston CD, Levine BA, Lecklitner ML, et al. Incidence and function of residual splenic tissue following splenectomy for trauma in adults. Arch Surg. 1983;118(5):617-620.

5. Basile RM, Morales JM, Zupanec R. Splenosis. A cause of massive gastrointestinal hemorrhage. Arch Surg. 1989;124(9):1087-1089.

6. Splenic Trauma. In: Grainger RG, Allison DJ, Dixon AK, eds. Grainger & Allison’s Diagnostic Radiology: A Textbook of Medical Imaging. 4th ed. New York, NY: Churchill Livingston; 2002:1443.

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8. Sikov WM, Schiffman FJ, Weaver M, et al. Splenosis presenting as occult gastrointestinal bleeding. Am J Hematol. 2000;65(1):56-61.

9. Agha FP. Regenerated splenosis masquerading as gastric fundic mass. Am J Gastroenterol. 1984;79(7):576-578.

10. Otteman MG, Wise JK, Henson SW Jr. Splenosis as lesion of the stomach. Rocky Mt Med J. 1972;69(2):53-54.

11. Deutsch JC, Sandhu IS, Lawrence SP. Splenosis presenting as an ulcerated gastric mass: endoscopic and endoscopic ultrasonographic imaging. J Clin Gastroenterol. 1999;28(3):266-267.

12. Kutzen BM, Levy N. Splenosis simulating an intramural gastric mass. Radiology. 1978;126(1):45-46.