Fine-needle aspiration of intrapancreatic accessory spleen, mimic of pancreatic neoplasms

Ferumoxytol-enhanced MR imaging for differentiating intrapancreatic splenules from other tumors

Objectives

Ferumoxytol is an ultra-small superparamagnetic iron oxide (USPIO) agent that is taken up by splenic tissue. This study describes our initial institutional experience of ferumoxytol-enhanced MRI (feMRI) for differentiating intrapancreatic splenules (IPS) from other pancreatic lesions.

Methods

In this retrospective study, patients with computed tomographic imaging that identified small enhancing lesions in the tail of the pancreas subsequently underwent feMRI for further characterization. The feMRI protocol included T2-weighted (T2w) imaging with and without fat suppression (FS), R2* mapping, diffusion-weighted imaging (DWI), and T1-weighted (T1w) imaging with FS, prior to contrast injection. Immediately after slow intravenous infusion with 3 mg/kg body weight ferumoxytol, T1w was repeated. Delayed imaging with all sequences were obtained 24–72 h after ferumoxytol administration.

Results

Seven patients underwent feMRI. In two patients, the pancreatic lesions were presumed as pancreatic neuroendocrine tumor (PNET) from feMRI and in the remaining 5 IPS. One of the two patients with PNET was symptomatic for NET. In another symptomatic patient with pathologically proven duodenal NET and suspected PNET, the pancreatic lesion was proven to be an IPS on feMRI. IPS demonstrated strong negative enhancement in feMRI on T2w and increased R2* values consistent with splenic tissue, while the presumed PNETs did not enhance. T2w FS was helpful on the pre-contrast images to identify IPS, while R2* did on post-contrast images. Neither DWI nor T1w contributed to differentiating PNETs from IPS.

Conclusions

This study demonstrates the potential utility of feMRI as a helpful adjunct diagnostic tool for differentiating IPS from other pancreatic lesions. Further studies in larger patient cohorts are needed.

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.

Recognizing intrapancreatic accessory spleen via EUS: Interobserver variability

Background and Objective:

Accessory spleen (AS) may be encountered as an intrapancreatic lesion on EUS. This can look similar to other pancreatic pathologies and may lead to unnecessary interventions. The goal of this study was to evaluate the accuracy of EUS in distinguishing intrapancreatic AS (IPAS) from other pancreatic lesions.

Materials and Methods:

Twelve sets of endoscopic images of the spleen and various pancreatic lesions confirmed on histology or cytology were gathered. Ten endosonographers were asked to characterize and identify the lesions. The responses were analyzed via Excel and the interobserver agreement was analyzed using Gwet's agreement coefficient statistic via Stata I/C v15.

Results:

In our sample, the interobserver agreement was 0.37 (−1–1; 0–0.2 poor, 0.2–0.4 fair, 0.4–0.6 moderate, 0.6–0.8 substantial, and 0.8–1.0 almost perfect) for determining whether or not the pancreatic lesion is IPAS. The reviewers were able to correctly determine IPAS endosonographically with a sensitivity of 77%, specificity of 74%, and positive and negative predictive values of 50% and 92%, respectively.

Conclusion:

There is a moderate-to-substantial interobserver agreement in describing the sonographic characteristics of the pancreatic lesions, such as the shape, echogenicity compared to spleen, echotexture, and border of the lesions. However, the interobserver agreement is only fair when deciding if the pancreatic lesion is an IPAS. The similar profile of IPAS and pancreatic neuroendocrine tumor could confound the diagnosis of IPAS, thus contributing to the decreased interobserver agreement. This study demonstrates that EUS criteria alone are not accurate for IPAS diagnosis. Fine-needle aspiration (FNA) may be required for a confirmatory diagnosis.

Intrapancreatic accessory spleen: utilization of fine needle aspiration for diagnosis of a potential mimic of a pancreatic neoplasm

Accessory spleen (AS) is not a rare occurrence, and with the second most common site being the tail of the pancreas, intrapancreatic AS (IPAS) can easily mimic a pancreatic neoplasm. Together with radiologic imaging findings, endoscopic ultrasound-guided fine needle aspiration (FNA) can be used to assist in the diagnosis, preventing potentially unnecessary surgical procedures. The most common cytologic findings that have been described in the literature include a heterogenous population of small lymphocytes along with traversing small vessels. Immunohistochemical staining for CD8 has also been documented as a useful tool to support the diagnosis as it specifically highlights the endothelial cells of the splenic sinus. Here, we report two additional cases of IPAS diagnosed by FNA and discuss the potential pitfalls in diagnosis of this entity.

Post-splenectomy intrapancreatic accessory spleen mimicking endocrine tumor of the pancreas

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The first case of IPAS arising after splenectomy.

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The IPAS has similar features of pancreatic neuroendocrine tumor on images.

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Typical pathologic data and characteristics of IPAS were presented and described.

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A brief review of IPAS was included.

INTRODUCTION

Intrapancreatic accessory spleen is an uncommon congenital abnormality of the spleen with no indication for surgical intervention. Among the few cases reported, IPAS coexisted with a normal spleen. We here report the first case of IPAS arising a couple years after splenectomy with the appearance of an endocrine tumor of the pancreas.

PRESENTATION OF CASE

A 62-year-old female presented with a one-week history of left upper quadrant discomfort. She had splenectomy for the treatment of hypersplenism caused by cirrhotic portal hypertension two years before this admission. Her physical examination was unremarkable and laboratory data was within the normal range. Both the ultrasonography and magnetic resonance image revealed a small oval-shaped mass in the tail of her pancreas with the diameter 2 cm or less. A distal pancreatectomy was performed for the suspection of malignant neuroendocrine tumor of the pancreas. An intrapancreatic accessory spleen was confirmed by the pathologic examination.

DISCUSSION

Intrapancreatic accessory spleen is one kind of congenital ectopic spleen without indication for operative intervention. We present the case to support that intrapancreatic accessory spleen may enlarge through a compensatory mechanism, and raise the awareness of this intrapacreatic entity to avoid unnecessary surgical operation.

CONCLUSION

IPAS should be highly considered as a differential diagnosis while the lesion is no more than 2.5 cm in diameter and/or other accessory spleens show around the splenic hilum.

Differentiation of an intrapancreatic accessory spleen from a small (<3-cm) solid pancreatic tumor: value of diffusion-weighted MR imaging

PURPOSE

To evaluate the value of diffusion-weighted (DW) imaging in differentiation of an intrapancreatic accessory spleen (IPAS) from a small (<3 cm) solid pancreatic tumor.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board, and informed consent was waived. Twenty patients with IPAS and 22 patients with small solid pancreatic tumors were included. All patients underwent abdominal magnetic resonance (MR) imaging with DW and gadoxetic acid-enhanced imaging. Qualitative (signal intensity) and quantitative (signal intensity and apparent diffusion coefficient [ADC]) evaluations were performed by two observers. Fisher exact test and Mann-Whitney U test were used for comparing groups.

RESULTS

Compared with the spleen, the IPAS showed isointensity more frequently than did small pancreatic tumors on T2-weighted images (95% [19 of 20] vs 41% [nine of 22]), arterial phase images (100% [20 of 20] vs 18% [four of 22]), portal phase images (100% [20 of 20] vs 23% [five of 22]), late phase images (100% [20 of 20] vs 41% [nine of 22]), and DW images with b value of 0 sec/mm(2) (100% [20 of 20] vs 9% [two of 22]), b value of 100 sec/mm(2) (95% [19 of 20] vs 27% [six of 22]), and b value of 800 sec/mm(2) (100% [20 of 20] vs 27% [six of 22]), with significant differences (P < .01). The means of the absolute value of relative signal intensity and ADC ratio on DW images of IPAS were significantly lower and closer to zero than those of pancreatic tumors (P < .05). Visual assessment of the similarity between pancreatic lesion and spleen on DW images for diagnosis of IPAS yielded diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 95% (40 of 42), 100% (20 of 20), 91% (20 of 22), 91% (20 of 22), and 100% (20 of 20), respectively, for observer 1 and 90% (38 of 42), 95% (19 of 20), 86% (19 of 22), 86% (19 of 22), and 95% (19of 20), respectively, for observer 2.

CONCLUSION

In addition to conventional morphologic MR imaging, DW imaging can be used as a tool for differentiating IPAS from solid pancreatic tumors.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112765/-/DC1.

Intrapancreatic accessory spleen imitating a pancreatic neoplasm

Accessory spleens are present in 10% of population and are formed during embryonic development. Besides the splenic hilum, the next most frequent localization of accessory spleens is the pancreatic tail. Intrapancreatic accessory spleens are usually diagnosed occasionally and make diagnostic difficulty because they imitate a pancreatic neoplasm. We present the case of a 61-year old woman with a mass in the pancreatic tail, diagnosed by computed tomography. The patient was operated with suspicion of neuroendocrine tumor. Postoperative histopathological examination revealed the intrapancreatic accessory spleen. We present possibilities of differential diagnosis.

Large platelet aggregates in endoscopic ultrasound-guided fine-needle aspiration of the pancreas and peripancreatic region: a clue for the diagnosis of intrapancreatic or accessory spleen

Intrapancreatic and intraabdominal accessory spleens (IPIASs) are rarely encountered in endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsies. However, as incidentally discovered IPIAS can mimic a benign or malignant pancreatic neoplasm on imaging studies, a definitive diagnosis made by EUS-FNA can avert an unnecessary surgical intervention or additional radiologic follow-up. We report five cases of intrapancreatic splenules and one case of accessory spleen (AS) in which a definitive diagnosis was made on EUS-FNA. Previously recognized FNA cytomorphologic features of splenic tissue, including ASs and splenosis, are endothelial cells and polymorphous lymphocytes admixed with neutrophils, eosinophils, plasma cells, histiocytes, and lymphoglandular bodies. We describe the additional finding of abundant large platelet aggregates as another distinguishing feature of splenic tissue on FNA. In all six cases, large platelet aggregates were identified along with polymorphous lymphoid cells, lymphoglandular bodies, loose aggregates of endothelial cells and scattered or aggregated bland spindle cells. A review of 10 consecutive cases of EUS-FNA-sampled benign intraabdominal lymph nodes showed that the presence of large platelet aggregates, three-dimensional aggregates of lymphoid cells and of bland slender spindle cells and the absence of follicular germinal cell components (tingible body macrophages and lymphohistiocytic aggregates) are useful in differentiating IPIASs from reactive lymph nodes. Immunoperoxidase stains were useful to confirm a suspected IPIASs by showing CD31-positive acellular flocculent material, consistent with large platelet aggregates and a rich CD8-positive endothelial cell network between CD45-positive lymphoid cells and CD68-positive histiocytes in all six cases.

Intrapancreatic accessory spleen: clinicopathologic analysis of 12 cases

OBJECTIVES

Intrapancreatic accessory spleen is a benign lesion that mimics hypervascular or cystic pancreatic neoplasm. A comprehensive clinicopathologic analysis has not yet been reported.

METHODS

We described the clinicopathologic characteristics of 12 cases of pathologically proven intrapancreatic accessory spleen, among which 6 had internal epidermoid cysts. Immunohistochemistry was done to clarify the origin of epidermoid cysts.

RESULTS

Most cases were incidentally detected in young adults. Two-thirds of cases with intra-lesional cysts showed elevated serum carbohydrate antigen 19-9 levels. Radiologically, heterogeneously enhancing a solid portion similar to the spleen was a helpful, but not convincing, feature. Grossly, a well-circumscribed dark red mass with or without cysts in the pancreatic tail was characteristic. Microscopically, small foci of pancreatic tissue were embedded within the splenic tissue. Epidermoid cysts consisted of modified squamous epithelium, some of which had intracellular mucin. Cytologic smears showed large aggregates of benign spindle cells that were reactive against CD8. Immunohistochemical staining of the cystic epithelium suggested its pancreatic ductal origin.

CONCLUSIONS

Intrapancreatic accessory spleen with or without epidermoid cyst should be considered as differential diagnoses when well-enhanced solid or cystic tumors are found in the pancreatic tail. Radiologic suspicion and preoperative aspiration or biopsy might minimize the need for unnecessary surgery.

Positive somatostatin receptor scintigraphy in accessory spleen mimicking recurrent neuroendocrine tumor

We report the case of a female patient who had a neuroendocrine tumor in the pancreatic tail. Followup using ⁶⁸Ga DOTA-d-Phe(1)-Tyr(3)-octreotide (DOTATOC) positron-emission tomography (PET)/computed tomography (CT) detected a round, well-circumscribed nodular mass that exhibited positive somatostatin receptors. This finding was highly suggestive of an accessory spleen; however, due to the slight elevation of the tumor marker, recurrence of the tumor or lymph node metastasis of the endocrine tumor was considered as well. Ultimately, splenic scintigraphy (SS) confirmed an accessory spleen. This case shows the benefit of splenic scintigraphy in excluding a recurrent neuroendocrine tumor by confirming an accessory spleen.