Intrapancreatic accessory spleen: a diagnostic dilemma

Imaging‑based diagnosis of intrapancreatic accessory spleen: A case report

During a routine ultrasound examination of the abdomen, a 60-year-old male patient was diagnosed with mass in the tail of the pancreas. However, computed tomography (CT) suggested that the lesion was an intrapancreatic accessory spleen (IPAS). IPAS is a congenital anomaly, which usually does not present with symptoms. IPAS occurs during embryologic splenic development when a portion of the splenic tissue fails to fuse with the main body of the spleen. IPAS does not require treatment, except when it is combined with idiopathic thrombocytopenic purpura. In the present case, the diagnosis of IPAS was confirmed using magnetic resonance imaging (MRI). On CT and MRI, the IPAS had a density and intensity comparable with that of the spleen in all plain and contrast-enhanced phases. Due to comorbidities, the patient refused further evaluation or surgery. The lesion was periodically monitored using CT every 1-2 years. Since the tumour was stable during the 7-year follow-up, it was concluded that it was an IPAS. In patients that cannot undergo surgery, a characteristic location (near the spleen) and imaging features (such as a 'zebra-patterned' enhancement in the arterial phase on CT and high signal intensity on diffusion-weighted imaging sequences on MRI, which is comparative to that of the normal spleen) may allow for a diagnose of IPAS with a high level of certainty. Being aware of this condition could aid a correct diagnosis of IPAS and prevent unnecessary surgery.

Intrapancreatic accessory spleens in African swine fever infection of wild boar (Sus scrofa)

Intrapancreatic accessory spleen (IPAS) is one of the most frequent congenital splenic anomalies in humans; however, studies in veterinary medicine are scarce. This study aimed to describe the macroscopic, histopathological and immunohistochemical features of 11 suspected cases of IPAS in wild boar piglets of 3-4 months old. Seven of the 11 animals were immunised with a low virulence isolate of African swine fever virus (ASFV) and subsequently challenged with a highly virulent ASFV isolate (LVI-HVI group). The remaining four animals were exclusively infected with a highly virulent isolate of ASFV (HVI group). Grossly, lesions comprised focal or multifocal reddish areas of variable shape, located on the surface of the pancreatic tail or within the parenchyma. Histological and immunohistochemical studies (anti-CD79 and CD3) confirmed the presence of IPAS in eight of the 11 cases. IPAS shared the same histological structure and alterations as those observed in the original spleen. The immunohistochemical study against ASFV revealed the presence of VP72+ cells in both the spleen and IPAS of seven of the eight piglets. The results of this study describe for the first time the presence of IPAS in ASFV infection of wild boar (Sus scrofa) regardless the isolate and suggest that the infection may induce the development of ectopic splenic tissue due to an increased demand for phagocytic cells from the reticuloendothelial system. However, further studies are needed to understand the immunological mechanisms that trigger the formation of these accessory organs.

An unusual presentation of accessory spleen mimicking a pancreatic neoplastic lesion in a splenectomized patient: A case report

Accessory spleen is a relatively common occurrence. However, an intrapancreatic accessory spleen can get hypertrophied following splenectomy and rarely mimic a pancreatic neoplasm leading to misdiagnosis. Here we present a 64-year-old male who had undergone left radical nephrectomy and splenectomy for renal cell carcinoma 14 years back, presenting with upper abdominal discomfort. He was found to have a mass in the pancreatic tail on imaging, suggesting an intrapancreatic neoplastic lesion. After a multidisciplinary team decision based on contrast-enhanced computed tomography and magnetic resonance imaging, he underwent an uncomplicated distal pancreatectomy, and the histology revealed an intrapancreatic accessory spleen. Contrast-enhanced computed tomography, magnetic resonance imaging, and positron emission tomography alone is not specific enough to confidently differentiate an accessory spleen preoperatively. Nuclear scintigraphy fused with contrast-enhanced computed tomography provides more specific and better anatomically localized evidence. Ultrasound-guided fine needle sampling showing lymphocytes with subsets of histiocytes, plasma cells, and immunohistochemistry showing CD8 positivity can be used to guide the definitive diagnosis. Differentiating an accessory spleen from a pancreatic neoplasm may be challenging preoperatively. Accessory spleen needs to be considered in the differential diagnosis of upper abdominal masses especially in patients who have undergone splenectomy.

Three-dimensional morphological analysis of the human spleen and its surrounding organs during the early fetal period

The spleen has variations in its morphology and is considered to acquire a defined shape in the third month of gestation. However, few studies have investigated spleen development during the first 3 months of fetal life. This study aimed to determine the three-dimensional (3D) morphogenesis of the spleen during the third month of gestation. In this study, 30 fetal specimens (crown-rump length [CRL]: 22-103 mm) were subjected to magnetic resonance imaging analysis. We manually segmented the spleen, stomach, and adrenal gland, reconstructed 3D models, and analyzed the volume and shape of these organs. The results showed that the variation in spleen size was large compared to that in other organs. Spleen morphology was classified into six types based on the number of splenic surfaces as follows: two-faced, three-faced, four-faced, five-faced, ovoid, and irregular. Two-faced spleens were only observed in small specimens, whereas three- and four-faced spleens were observed in larger specimens. We also revealed that the number of fetal splenic surfaces increased as CRL enlarged. Additionally, 3D models indicated that some specimens formed their splenic surfaces without contact with the adjacent organs. This suggested that the splenic surface may be caused not only by pressure from the faced organs but also by an intrinsic program. This study may provide a better understanding of the normal development of the spleen during the early fetal period, and may potentially assist future studies in investigating congenital morphological anomalies of the spleen.

Diagnostic accuracy of apparent diffusion coefficient to differentiate intrapancreatic accessory spleen from pancreatic neuroendocrine tumors

BACKGROUND

Intrapancreatic accessory spleen (IPAS) shares similar imaging findings with hypervascular pancreatic neuroendocrine tumors (PNETs), which may lead to unnecessary surgery.

AIM

To investigate and compare the diagnostic performance of absolute apparent diffusion coefficient (ADC) and normalized ADC (lesion-to-spleen ADC ratios) in the differential diagnosis of IPAS from PNETs.

METHODS

A retrospective study consisting of 29 patients (16 PNET patients vs 13 IPAS patients) who underwent preoperative contrast-enhanced magnetic resonance imaging together with diffusion-weighted imaging/ADC maps between January 2017 and July 2020 was performed. Two independent reviewers measured ADC on all lesions and spleens, and normalized ADC was calculated for further analysis. The receiver operating characteristics analysis was carried out for evaluating the diagnostic performance of both absolute ADC and normalized ADC values in the differential diagnosis between IPAS and PNETs by clarifying sensitivity, specificity, and accuracy. Inter-reader reliability for the two methods was evaluated.

RESULTS

IPAS had a significantly lower absolute ADC (0.931 ± 0.773 × 10^-3 mm²/s vs 1.254 ± 0.219 × 10^-3 mm²/s) and normalized ADC value (1.154 ± 0.167 vs 1.591 ± 0.364) compared to PNET. A cutoff value of 1.046 × 10^-3 mm²/s for absolute ADC was associated with 81.25% sensitivity, 100% specificity, and 89.66% accuracy with an area under the curve of 0.94 (95% confidence interval: 0.8536-1.000) for the differential diagnosis of IPAS from PNET. Similarly, a cutoff value of 1.342 for normalized ADC was associated with 81.25% sensitivity, 92.31% specificity, and 86.21% accuracy with an area under the curve of 0.91 (95% confidence interval: 0.8080-1.000) for the differential diagnosis of IPAS from PNET. Both methods showed excellent inter-reader reliability with intraclass correlation coefficients for absolute ADC and ADC ratio being 0.968 and 0.976, respectively.

CONCLUSION

Both absolute ADC and normalized ADC values can facilitate the differentiation between IPAS and PNET.

Refractory immune thrombocytopenic purpura (ITP) after accessory splenectomy: A case report and literature review

Immune thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by a platelet count of less than 100 x 109 /L, resulting from antibody-mediated platelet destruction. Treatment for ITP typically involves steroids, and intravenous immunoglobulins (IVIG) can be added. Splenectomy is performed in cases with refractory ITP. Rituximab can suppress immunity but has limited efficacy in ITP cases. Herein, we present a rare case of a 30-year-old female who was first diagnosed with ITP and underwent a splenectomy two years later. However, seven years after surgery, she was presented with symptoms of ITP. A splenic scan showed an accessory spleen in the spleen bed, for which she underwent accessory spleen removal surgery. Her laboratory tests three days post-operation showed a rise in platelet count and hence was discharged a few days later. The patient had recurrent attacks of ITP even after the removal of the normal and accessory spleen, suggesting that accessory spleen removal may not always be an effective treatment for ITP. The patient eventually died. While splenectomy is a common treatment for ITP, it may not always be effective in all cases, and other treatments such as bone marrow transplantation may be necessary.

Accessory Spleen Masquerading as an Intrapancreatic Tumor: A Case Report

The finding of splenic tissue within the pancreas, also known as splenosis or intrapancreatic accessory spleen (IPAS), is a relatively uncommon condition that presents as an intrapancreatic mass. The discovery of an intrapancreatic mass often prompts a thorough diagnostic workup for a primary pancreatic malignancy, often exposing patients to unnecessary risks associated with invasive testing and even surgery. The benign, asymptomatic nature of this finding places emphasis on utilizing non-invasive techniques for confirmation of the diagnosis, reducing risks of morbidity and mortality in this patient population. Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) will display near-identical signal intensities (SI) between the spleen and the intrapancreatic mass, as well as identical contrast-enhancement patterns. Nuclear medicine evaluation with Tc-99m heat-damaged red blood cells (HDRBCs) is often used as a confirmatory test and allows for differentiation from malignancies.

Cavernous hemangioma of an intrapancreatic accessory spleen mimicking a pancreatic tumor: A case report

BACKGROUND

Intrapancreatic accessory spleen (IPAS) is an uncommon condition, with the majority of cases presenting as solid lesions. Thus, this condition is frequently misdiagnosed as pancreatic solid neoplasm. Moreover, splenic cavernous hemangioma is a rare disorder, whereas lesions with a cystic appearance arising from IPAS have not been reported.

CASE SUMMARY

Herein, we present a case involving a 32-year-old male who had a complex cystic lesion in the tail of the pancreas revealed by conventional ultrasound. The lesion was misdiagnosed as a pancreatic cystadenoma because of its confusing anatomic location, as well as due to its peripheral nodular and internal septal enhancement patterns on contrast-enhanced ultrasound. After multidisciplinary discussion, the patient finally underwent laparoscopic pancreatic body and tail resections. Postoperative pathology demonstrated the lesion to be a cavernous hemangioma arising from the IPAS.

CONCLUSION

Cavernous hemangioma in the intrapancreatic accessory spleen may mimic pancreatic cystadenoma, which is a condition with the potential to be malignant. Imaging follow-ups or surgical interventions may be helpful for the exclusion of malignant risks in complicated cystic lesions, especially those with parietal and septal enhancements.

Spleno-adrenal fusion mimicking an adrenal metastasis of a renal cell carcinoma: A case report and embryological background

Foci of splenic tissue separated from the spleen can occur as a congenital anomaly. Isolated nodules of splenic tissue are called accessory spleens or spleniculli. However, nodules of splenic tissue can merge with other organs during embryonic development, in which case we speak of spleno-visceral fusions: most often, they merge with the tail of the pancreas (thus forming spleno-pancreatic fusion or an intrapancreatic accessory spleen), with the reproductive gland (i.e., spleno-gonadal fusion), or with the kidney (i.e., spleno-renal fusion). Our case report describes the fusion of heterotopic splenic tissue with the right adrenal gland, which was misinterpreted as a metastasis of a renal cell carcinoma. To the best of our knowledge, this is the first reported case of spleno-adrenal fusion. Spleno-visceral fusions usually represent asymptomatic conditions; their main clinical significance lies in the confusion they cause and its misinterpretation as tumors of other organs. We believe that the cause of retroperitoneal spleno-visceral fusions is the anomalous migration of splenic cells along the dorsal mesentery to the urogenital ridge, together with primitive germ cells, at the end of the fifth week and during the sixth week of embryonic age. This theory explains the possible origin of spleno-visceral fusions, their different frequency of occurrence, and the predominance of findings on the left side.

68Ga-Prostate-Specific Membrane Antigen Uptake in a Pancreatic Neuroendocrine Tumor

We present a 60-year-old man with known prostate cancer treated with robot-assisted radical prostatectomy. Prostate-specific antigen levels did not decline accordingly, and a second Ga-PSMA PET/CT demonstrated a new focus with high Ga-PSMA uptake in the pancreatic tail. A subsequent CT scan did not display the lesion as a typical pancreatic tumor, and a spleen scintigraphy was also negative excluding an ectopic intrapancreatic accessory spleen. Ga-DOTATOC PET/CT showed uptake in the same area of the pancreatic tail consistent with a neuroendocrine tumor. This case illustrates that neuroendocrine tumors can be important pitfalls in Ga-PSMA PET/CT performed in prostate cancer patients.

Intrapancreatic accessory spleen false positive to 68Ga-Dotatoc: case report and literature review

Background

Intrapancreatic accessory spleen (IPAS) is an uncommon finding of pancreatic mass. Differential diagnosis with pancreatic tumor, especially with non-functional neuroendocrine tumor (NF-NET), may be very hard and sometimes it entails unnecessary surgery. A combination of CT scan, MRI, and nuclear medicine can confirm the diagnosis of IPAS. 68-Ga-Dotatoc PET/CT is the gold standard in NET diagnosis and it can allow to distinguish between IPAS and NET.

Case presentation

A 69-year-old man was admitted to our hospital for an incidental nodule in the tail of the pancreas with focal uptake of 68-Ga-dotatate at PET/CT. NET was suspected and open distal splenopancreatectomy was performed. Pathologic examination revealed an IPAS.

Conclusion

This is the second IPAS case in which a positive 68Ga-Dotatoc uptake led to a false diagnosis of pancreatic NET. Here is a proposal of a literature review.

Intrapancreatic accessory spleen mimicking malignant tumor: three case reports

Intrapancreatic hypervascular lesions may represent metastases, neuroendocrine tumors, or intrapancreatic accessory spleens. The benign intrapancreatic accessory spleen can be difficult to separate from a malignant neuroendocrine tumor or metastasis. We report three cases of pancreatic lesions that underwent pancreatic surgery due to suspicion of malignancy on imaging; all cases were histologically intrapancreatic accessory spleens. Our cases point to the importance of performing single-photon emission computed tomography with heat-damaged Tc-99m-pertechnetate labelled erythrocytes to identify splenic tissue, even though small lesions can show a false-negative result.

Sometimes things are what they seem

Accessory spleen is a frequent congenital abnormality (10-20%) resulting in the fusion failure of splenunculi. We present a case report of a 74 year-old man with a nodule identified in the tail of the pancreas of 1.8 cm x 1.5 cm in size. The CT scan showed soft tissue attenuation and arterial hyperenhancement with a lower uptake in the central area, low 18-FDG affinity and no evidence of 111-In-octretide uptake. A solid, round and well-circumscribed nodule was defined as an intrapancreatic accessory spleen (IPAS) by endoscopic ultrasound (EUS), due to shared ultrasonographic characteristics and a pattern of contrast enhancement with the spleen. The material obtained by EUS guided puncture was consistent with a lymph node. A distal pancreatectomy confirmed the presence of an IPAS.

Intrapancreatic accessory spleen: an enigmatic entity

Solitary hypervascular lesion in the distal body/tail of pancreas in a patient with non-specific abdominal symptoms is a diagnostic challenge. Neuroendocrine neoplasm (NEN) and metastasis from renal cell carcinoma are the most common differentials and intrapancreatic accessory spleen (IPAS) is the rarest of its differential diagnosis. We present, here, a case of a 56-year-old man with a space-occupying lesion in body/tail of pancreas that was preoperatively diagnosed as a NEN based on elevated chromogranin levels and hyperenhancing lesion on contrast-enhanced CT scan. He underwent a spleen-preserving distal pancreatectomy. The final histopathology revealed an IPAS.