Incidental finding of intramural splenic heterotopy in the colon mimicking subepithelial neoplasm: a case report

Abstract

Aim

The aim of this case report is describe an unprecedented case with histological and immunohistochemical diagnosis of splenic heterotopy in the colon using material obtained by endoscopic ultrasound-guided biopsy.

Background

Splenic heterotopia is a benign condition characterized by the implantation of splenic tissue in areas distant from its usual anatomical site, such as the peritoneum, omentum, mesentery, liver, pancreas, and subcutaneous tissue and, more rarely, in locations such as the colon and brain. It is generally associated with a history of splenic trauma or splenectomy and typically does not cause specific symptoms.

Case presentation

A 35-year-old white male patient who was healthy, with no history of trauma or splenectomy, but had a family history of colorectal neoplasia underwent colonoscopy for screening. The examination revealed a large bulge in the proximal descending colon, covered by normal-appearing mucosa. Endoscopic ultrasound-guided puncture was performed with a 22 gauge fine needle biopsy, and the histopathological and immunohistochemical analysis results were consistent with a heterotopic spleen.

Conclusions

This is the first report of a primary intramural colic splenosis case with histological and immunohistochemical diagnosis of splenic heterotopia in the colon, using material obtained by endoscopic ultrasound and ultrasound-guided biopsy.

Background

Splenic heterotopia is a benign condition involving the implantation of splenic tissue in areas distant from its usual anatomical site, such as the peritoneum, omentum, mesentery, liver, pancreas, and subcutaneous tissue and, more rarely, areas such as the colon and brain. It is typically related to a history of splenic trauma or splenectomy and does not cause specific symptoms. Often recognized as “splenosis,” splenic heterotopia conceptually encompasses any situation where splenic tissue implants in areas distant from its usual anatomical site, usually secondary to traumatic abdominal injuries or splenectomy. The term “splenosis” was introduced in 1939 by Buchbinder and Likpoff [1] to describe multiple nodules of splenic tissue following spleen rupture. Some authors suggest histopathological differences between splenic tissue implants and lesions compatible with accessory spleen or splenic heterotopia [2], such as the number of germinal centers, absence of terminal arterial capillaries, and poor definition of follicles [3,4,5,6,7]. In the present case, we describe a splenic heterotopia. It is a benign condition, normally asymptomatic or related to nonspecific symptoms, such as abdominal pain and bleeding [8], in which the presence of splenic implants is noted in places such as the peritoneum, omentum, mesentery, liver, pancreas, and subcutaneous tissue and, more rarely, areas such as the colon and brain [9,10,11,12]. The first two reports in humans were incidental findings from autopsies by Albrecht in 1896 and by Schilling in 1907 [13], both involving multiple peritoneal implants of splenic tissue, in patients with no history of injury or trauma [14]. In 1984, Sirinek described the first case of colon obstruction secondary to compression by an ectopic spleen adjacent to the sigmoid colon after traumatic splenic rupture, suggesting for the first time that these lesions could be anatomically associated with colonic segments and cause local symptoms [14]. In 2006, Kravarusic reported a case of a 12-year-old child with spherocytosis who underwent elective splenectomy. Persistent anemia and thrombocytopenia led to the identification of an intraluminal mass in the left colon near the splenic flexure during diagnostic exploratory laparotomy. Histopathological analysis confirmed it as a functioning intramural colonic splenic implant, the first recorded instance of this condition [2]. In 2012, Obokhare reported the second case of intramural colic splenic heterotopia in a 41-year-old adult with abdominal pain, constipation, and melena who had a history of abdominal trauma and splenectomy for gastric varices. Colonoscopy revealed a polypoid and ulcerated mass, causing partial obstruction of the intestinal lumen near to the splenic flexure [15].

Additional literature reports describe splenic tissue implants mimicking colon and rectal tumors [16, 17], with evidence of intraluminal masses diagnosed by imaging tests such as colonoscopy and tomography, leading to intestinal intussusception [18], bleeding, and abdominal pain [15]. However, the present case is notable for its rarity, underscoring the need for clinicians to be aware of such potential presentations. This case contributes to the existing body of knowledge and emphasizes the importance of considering splenic heterotopia in differential diagnoses, particularly in patients with pertinent medical histories. This is the first report of a case of primary intramural colic splenosis with histological and immunohistochemical diagnosis of splenic heterotopia in the colon, using material obtained by endoscopic ultrasound-guided biopsy.

Case presentation

A 35-year-old white male patient who was healthy and asymptomatic and had no abnormalities on physical examination and no history of trauma or splenectomy but had a family history of colorectal neoplasia underwent colonoscopy for screening. Examination showed a large bulging in the proximal descending colon covered by normal-appearing mucosa (Fig. 1).

Fig. 1

Bulging in the descending colon, measuring approximately 30 mm, covered by normal-looking mucosa. Arrows indicate subepithelial lesion

Endoscopic ultrasound revealed an oval, regular, hypoechoic, and homogeneous lesion, measuring approximately 2.63 cm × 1.67 cm, with difficult definition of its layer of origin, suggesting it originated from the submucosa or the muscularis propria layer, raising the hypothesis of mesenchymal neoplasia (Fig. 2).

Fig. 2

Oval, regular, hypoechoic, and homogeneous lesion, with difficult definition of its layer of origin and measuring 2.75 cm × 1.80 cm. Ultrasound-guided puncture was performed with a 22G fine needle biopsy (FNB) needle. Arrows indicate fine needle biopsy and subepithelial lesion

Endoscopic ultrasound-guided puncture was performed with a 22G fine needle biopsy (FNB) needle, and histopathological and immunohistochemical analysis confirmed a heterotopic spleen neoplasia (Figs. 3, 4). On the basis of the results, given that it is a benign condition and in the absence of associated signs and symptoms, a conservative management approach was chosen in a shared decision with the patient.

Fig. 3

Microhistology of a sample collected by ultrasound-guided puncture of a colon subepithelial lesion. Hematoxylin and eosin (H&E) showing an ectopic lymphoreticular tissue with splenic characteristics: the red pulp—a mixed population of small lymphocites, plasma cells and histiocytes (red arrows)—and the white pulp—mainly lymphocytes (orange arrows) with small arterioles (*)

Fig. 4

Immunohistochemical analysis showing positivity for leucocyte commom antigen (CD45) white blood cells (a) and splenic sinusoidal littoral cells or sinusoidal lining cells positivity for CD8 (blue arrows). The analysis also shows negativity for chromogranin, synaptophysin, and C-kit

Discussion

The reported case is notable due to the absence of a history of trauma or surgery. The patient was asymptomatic and showed no abnormalities on physical examination. During colonoscopy, instead of an intraluminal mass resembling a neoplastic lesion, a bulge covered by normal mucosa was observed, suggesting a subepithelial lesion.

In the literature only two cases of splenic heterotopia with intramural implantation in the colon as a subepithelial lesion have been reported—by Kravarusic in 2016 and Obokhare in 2012 [2, 15]. Splenic tissue implantation, in the absence of a history of trauma or surgery, can be attributed to defects during embryonic development, characterizing primary splenosis [13, 15]. To date, all cases of intramural splenic heterotopia in the colon derive from secondary splenosis processes, making this the first report of primary intramural colic splenosis.

Splenic tissue implantation in atypical locations is often asymptomatic and clinically insignificant [14]. Its differential diagnosis varies depending on its location and includes conditions such as endometriosis, metastatic implants, hemangiomas, and malignant neoplasms [19]. The most accurate method currently involves a combination of computed tomography with technetium scintigraphy (Tc 99 m), an examination often limited in accessibility, as it is performed only in specific nuclear medicine centers requiring specialized equipment and radiopharmaceuticals [20, 21].

Colonoscopy provides adequate visualization of colonic implants, allowing precise determination of lesion location. In cases with suggestive clinical history, with reports of abdominal trauma or splenectomy, combined radiological methods may suffice for diagnosis [17]. In asymptomatic patients, surgical resection is not recommended [17]. However, in cases of diagnostic uncertainty and incongruous clinical history, histopathological confirmation is necessary to differentiate neoplastic lesions [17].

Endoscopic ultrasound with tissue acquisition is a valuable diagnostic method for these lesions, offering an important tool with increasing availability. Proper sample treatment (micro-histology) indicates the diagnosis and allows ancillary methods such as immunohistochemistry, showing a mixed lymphohistiocytic population and sinusoidal coastal cells, ensuring adequate and less invasive management.

As the patient is asymptomatic and the examination finding was incidental, it was recommended that there need not be any treatment or follow-up of the lesion.

Conclusion

This is the first report of a case of primary intramural colic splenosis with histological and immunohistochemical diagnosis of splenic heterotopia in the colon, using material obtained by endoscopic ultrasound-guided biopsy. The case demonstrated the feasibility of performing an evaluation with a radial endoscopic ultrasound (EUS) followed by linear EUS and performing a fine needle aspiration (FNA).