“Sneaky Spleen”: Three Cases of Ectopic Splenic Tissue Mimicking Neoplasia

A choledochal cyst (CC) is one of the rare congenital diseases of the biliary tract and is more common in females. The association of ectopic pancreatic and splenic tissue with CC is an extremely rare condition. An 11-year-old girl child presented with a vague abdominal lump and intermittent dull abdominal pain for 5 months with early satiety and weight loss in the current case scenario. Her laboratory findings were normal. A type IV CC was discovered on ultrasonography, and the distal common bile duct displayed significant cystic dilatation on magnetic resonant cholangiopancreatography. After the CC was surgically removed, it was sent for histopathological examination. Sections revealed dual heterotropic elements, which included pancreatic and splenic tissues in a CC. It was very uncommon for both to exist independently in the CC and in this instance, both were observed together. This will be the first documented case, in which the CC contained dual ectopic tissue from the spleen and pancreas. Ectopic splenic tissue in the CC has never been documented in the literature. It is crucial to be aware of this entity when splenic or pancreatic tissue experiences changes due to inflammation, even though its clinical significance is uncertain. In the ectopic rests, bleeding, blockage, and malignant transformation are the possible outcomes.

Ectopic splenic tissue (accessory spleen or splenosis) occurs as dark-red-to-brown or purple nodules outside the spleen. Accessory spleens are congenital lesions histologically identical to a normal spleen. Splenosis results from implantation of splenic tissue following splenic rupture and lacks features of normal spleen. However, these distinctions have been largely applied to human cases, and the terms are often used interchangeably in domestic animals. Here we describe ectopic splenic tissue in 46 canine surgical biopsy specimens examined at the Athens Veterinary Diagnostic Laboratory, 2000-2024. The omentum (39 cases) and mesentery (5) were the most commonly affected sites. Original diagnoses were accessory spleen (28 cases), splenosis (14), accessory spleen or splenosis (2), and ectopic splenic tissue and normal splenic tissue (1 each). Updated diagnoses, modified after histologic assessment for a fibrous capsule, smooth muscle trabeculae, and white and red pulp, were accessory spleen (37 cases) and splenosis (9). Concurrent splenic lesions were reported in 12 cases in which accessory spleens were diagnosed and only 2 splenosis cases, confirming that the histologic diagnosis of accessory spleen and splenosis is not always correlated with the clinical history and gross findings (no splenic lesions vs. splenic lesions with rupture). For that reason, ectopic splenic tissue may be a more inclusive and better term for these lesions. Hemangiosarcoma was diagnosed in the spleen in 4 of the 12 cases with splenic masses, which underscores the importance of the differentiation between ectopic splenic tissue and hemangiosarcoma.

INTRODUCTION: Gastric subepithelial lesions (SEL) are found as often as 1 in 300 endoscopies. Indolent growing gastric splenosis mimicking a gastrointestinal stromal tumor (GIST) is rare. We present a case of a patient with a gastric SEL with growth concerning for a GIST that ultimately was diagnosed as ectopic splenic tissue (splenosis). This case highlights the importance of considering splenosis as a possible etiology for enlarging gastric SEL in patients with prior splenectomy. CASE DESCRIPTION/METHODS: A 52-year-old female with a remote history of solid pseudopapillary neoplasm (SPN) of the pancreas who received distal pancreatectomy and splenectomy 15 years ago presented with dyspepsia. 10 years ago, an esophagogastroduodenoscopy (EGD) revealed a 10-mm SEL in the gastric fundus. On endoscopic ultrasound (EUS) the lesion was described as a hypoechoic mass in the muscularis propria. Fine needle aspiration (FNA) was not performed given its challenging location. The patient opted for 4 years of annually computed tomography surveillance with stability of the lesion which was thought to be an accessory spleen. However, one year ago she presented to our clinic with dyspepsia. EUS revealed growth of the mass to 22.5 × 13.5 mm in the fourth layer with minimal vascularity suggestive of a GIST. Again, FNA was unsuccessful given its location in the greater curvature of the gastric fundus. Exploratory laparotomy was performed, the mass was excised, and pathology showed benign splenic tissue, consistent with splenosis. DISCUSSION: Splenosis and accessory spleen were considered initially as differential diagnoses in our patient given her splenectomy history. However, the indolent growth of the SEL and EUS appearance raised the concern of GIST. It is imperative to distinguish a GIST from other types of tumors to assess its malignant potential and treatment. Surgical excision was ultimately performed in our patient and the diagnosis of splenosis was made. Splenosis is a subtype of ectopic splenic tissue differentiated from accessory spleen, in that splenosis is acquired heterotopic autotransplantation and implantation of splenic tissue (usually after splenic trauma or splenectomy) while accessory spleen is a congenital anomaly with splenic arterial supply. Clinicians should be aware of the growth potential of splenosis as a mimicker of GISTs and other gastric SELs and consider ectopic splenic tissue a cause of SEL in patients without spleen.Figure 1.: EGD findings: Subepithelial nodule in the gastric fundus (year 0 vs year 9).Figure 2.: EUS findings (year 9): 22.5 × 13.5 mm well-defined hypoechoic and homogeneous mass arising from the fourth layer.Figure 3.: Histopathologic findings of subepithelial lesion: Benign splenic tissue, consistent with splenosis. (Hematoxylin-eosin x 100).

Application of heat-damaged Tc-99m RBCs in a patient with suspected hepatic metastasis

<h3>To the Editor.</h3> —Drs Zarrabi and Rosner's conclusion¹that splenosis (ectopic autotransplanted splenic tissue) may not offer protection against post-splenectomy sepsis should be extended to include accessory spleens. Indeed, one of their patients²had an accessory spleen rather than ectopic splenic tissue. We recently saw a 74-year-old man who had splenectomy for trauma ten years prior to admission and who had a recent development of non-insulin-dependent diabetes. He complained of diffuse central abdominal pain of four hours' duration and watery diarrhea of three days' duration. He was nauseated but had not vomited. His rectal temperature was 40 °C and BP 80/50 mm Hg sitting and 110/50 mm Hg supine. The bowel sounds were diminished. He became severely hypoxic soon after admission (arterial oxygen pressure, 49.1 mm Hg; pH, 7.175) and suffered a cardiopulmonary arrest. Resuscitation was unsuccessful. A peripheral blood smear was not done. At autopsy, a pure

This article provides a comprehensive review of studies and case analyses on ectopic splenic tissue, with a particular focus on renosplenic disease. Ectopic splenic tissue refers to the abnormal non-physiological localization of spleen tissue, commonly resulting from splenic tissue implantation or hematogenous metastasis following splenectomy. Renosplenic disease is rare and often misdiagnosed as a renal tumor or tumor recurrence, which can lead to unnecessary surgical interventions. By discussing two cases of postoperative renosplenic disease in detail and combining them with a literature review, this article explores the pathogenesis, clinical presentation, imaging characteristics, and diagnostic methods of the condition. Analysis of 39 previously reported cases of nephrosplenopathy revealed that it predominantly affects male patients, typically occurs on the left side, and is often associated with a history of splenectomy, with lesions identified on average 20 years post-splenectomy. The clinical manifestations of nephroplenic disease are nonspecific and are mostly incidental findings during imaging examinations. Hybrid SPECT/CT and SPIO-enhanced MRI are considered the gold standards for diagnosing ectopic splenic tissue. However, the majority of cases are still confirmed through needle biopsy or surgical resection. While surgical diagnosis allows for lesion removal, it also carries risks of postoperative complications, such as intestinal fistula, as reported in one of the cases in this study. Research indicates that ectopic splenic tissue is generally benign but can cause symptoms by compressing adjacent structures. For asymptomatic patients, conservative management or active surveillance is a viable approach. However, in cases of large lesions, the decision between conservative treatment and surgical intervention should be carefully weighed. By summarizing 48 years of nephroplenic disease case data, this article aims to provide a clinical reference for the diagnosis and management of the condition. It emphasizes the critical role of imaging examinations and the potential for conservative treatment, aiming to reduce surgical risks and recovery times while improving diagnostic accuracy, treatment outcomes, and patients’ quality of life.

Splenogonadal fusion is a rare congenital anomaly in which an abnormal attachment found between splenic tissue and gonads or mesonephric derivatives. There are two anatomic types: continuous and discontinuous. It is commonly mistaken for testicular tumor. We report the case of a 10-year-old child in whom an inguinal mass indicated surgical exploration. The ectopic tissue was completely removed with preservation of the testis. Histopathological examination was reported as ectopic splenic tissue. Splenogonadal fusion is a benign lesion, which should be considered in the differential diagnosis of testicular masses.

Splenic tissue in the ovary: Splenosis, accessory spleen or spleno-gonadal fusion?

Accessory spleen (AS) is a congenital ectopic splenic tissue arising during embryologic period of development, most remaining asymptomatic and discovered incidentally. Being present near the splenic hilum usually, it may occasionally be embedded partly or wholly in the tail of the pancreas, sometimes becoming symptomatic and even mimicking tumor. We report a case of an accessory spleen discovered during cadaveric dissection of a middle-aged man in the Department of Anatomy, RIMS, Imphal. Awareness of the possible presence of AS is important during splenectomy for conditions such as immune thrombocytopenic purpura as failure to remove the AS may result in the failure of the condition to resolve. Additionally, during medical imaging, AS may be confused for enlarged lymph nodes or neoplastic growths. The presented case report might remind us the sort of such congenital anomalies during clinical evaluations like splenomegaly, splenic trauma, lymphadenopathies and intra-abdominal mass and subsequent operative strategies. KEY MESSAGE: A routine search for AS intraoperatively along with preoperative radiological scan is recommended to achieve the highest detection rates and to prevent disease recurrence, especially for autoimmune hematological disorders. INTRODUCTION: The spleen consists of a large encapsulated mass of vascular and lymphoid tissue situated in the upper left quadrant of the abdominal cavity between the fundus of the stomach and the diaphragm. The spleen can display various developmental anomalies, including complete agenesis, multiple spleens or polysplenia, isolated small additional splenunculi and persistent lobulation1. Accessory spleens may be formed during embryonic development as ectopic or separated splenic tissue along the path from where the spleen forms at the midline to the spleen's final location on the left side of the abdomen.1, 2 Accessory spleen, found in 10%-30% of patients at autopsy, is due to the fusion failure of the splenic anlage, which is located in the dorsal mesogastrium. 3- 5 The splenic hilus is the most common site of an accessory spleen followed by pancreatic tail. Because an accessory spleen does not usually require treatment, accurate preoperative diagnosis is important.

A newborn presents with a scrotal mass.The baby was sent home after 2 days in the well baby nursery with instruction for surgical follow-up for the scrotal mass, which was believed to be a left inguinal hernia. At 6-month follow-up, the infant was normally developed for his age. On genital examination, the right testis was not palpable in the scrotum, the left testis was in the scrotum, and an elastic mass was identified at the upper pole of the left testis. No other physical abnormalities were detected. Results of all laboratory investigations were normal.Surgery revealed a red-brown encapsulated mass fused to the left testis. No connection could be seen between the spleen and the mass. There was no testicular torsion (Fig 1-4). Biopsy was performed after informed consent was obtained from his parents, and pathology identified the mass as splenic tissue.Approximately 150 cases of SGF are reported in the literature. The first description was by Pommer in 1889 in an infant who had limb abnormalities. SGF results from abnormal connection of splenic tissue with gonadal-mesonephric structures. The ectopic spleen generally is found within the tunica albuginea, separated from the testicular tissue by a fibrous capsule.SGF is far more common in males, in whom the appearance usually is a scrotal mass. The higher prevalence among males probably is due to the anatomic location of the testes, allowing ready and frequent palpation. Putschar and Manion classified SGF into two types: continuous (direct connection between the spleen and gonad) and discontinuous (no anatomic connection between ectopic splenic tissue and the principal spleen). Limb defects, micrognathia, or other congenital malformations such as cryptorchidism, ventricular septal defects, anal atresia, microgastria, spina bifida, or continuous type craniosynostosis often accompany SGF.SGF is assumed to occur between 5 and 8 weeks of gestation, before the beginning of gonadal descent. Its cause remains unclear, but two theories predominate. Sneath has suggested that slight inflammation of the peritoneal surfaces over the spleen and gonadal ridge can produce partial fusion of the two organs. von Hochstetter postulated that a retroperitoneal pathway for splenic anlage cells may allow contact with the gonadal anlage.Ultrasonography is the current imaging modality of choice for assessment of scrotal abnormalities, but findings are not conclusive. If SGF is suspected clinically before surgery, the diagnosis may be confirmed by 99m Tc-sulfur colloid imaging, which shows uptake in both the spleen and the accessory splenic tissue within the scrotum. Symptoms attributable to the presence of SGF include testicular pain after gastroenteritis, bowel obstruction, and acute scrotal pain resembling testicular torsion. Because of the rarity of SGF, it usually is not diagnosed preoperatively.This uncommon congenital abnormality is difficult to diagnose both clinically and with imaging. If a patient has congenital limb defects in conjunction with cryptorchidism or high ectopia, the possibility of SGF should be considered. Awareness of the entity is crucial to avoid misdiagnosis of a tumor.Ultrasonography, laparoscopic exploration, and scintigraphic scanning generally are necessary to demonstrate the distribution of splenic tissue, thereby allowing proper diagnosis and treatment. If intraoperative biopsy reveals splenic tissue, orchiectomy is not indicated. Surgery is necessary for the usual or unusual indications, such as hernia, cryptorchidism, and torsion. The ectopic spleen usually can be dissected away and the testis salvaged. Laparoscopic surgery should be considered for most uncomplicated cases.JoDee M. Anderson, MD, Division of Neonatal Medicine, Oregon Health & Science University, Portland, OR

A Rare Case of Ectopic Splenic Transplantation in a 16 Year Old with Hereditary Spherocytosis

Pancreases from 8 patients with trisomy 13 were studied. Ectopic splenic tissue was present in 6: 3 had accessory spleens and ectopic splenic tissue embedded in the pancreas, one had intrapancreatic splenic tissue without an accessory spleen, and one had an accessory spleen without intrapancreatic splenic tissue. The intrapancreatic splenic tissue was multiple, generally poorly or nonencapsulated, and contained pancreatic acini, islets of Langerhans, and ducts lined by tall columnar epithelium with goblet cells. The rest of the pancreas in these and other cases of trisomy 13 had microcyst formation and focal proliferations of small ducts similar to those seen in the splenic tissue. This constellation of features appears to be distinctive of trisomy 13.

Subcutaneous Splenosis Presenting 37 years post-traumatic splenectomy; A Case Report

Ectopic splenic tissue was found on the pancreas of a capuchin monkey (Cebus albifrons), although it had no connection to the main body of the spleen. Both the ectopic tissue and the spleen itself were histologically normal.

Splenosis Presenting as a Left Renal Mass Indistinguishable from Renal Cell Carcinoma