Imaging Pearls ❯ Pancreas ❯ Intrapancreatic Accessory Spleen
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- Background: Identification of incidental pancreatic lesions is increasing because of advancements in imaging. Diagnosis remains a challenge for clinicians, with intrapancreatic accessory spleens (IPAS) posing a unique dilemma. IPAS are frequently resected because of inability to exclude alternate diagnoses, subjecting patients to unnecessary risk. The purpose of this study was to examine our institutional experience with IPAS and develop a multidisciplinary algorithm to improve preoperative diagnosis.
Conclusions: Incidental pancreatic lesions like IPAS remain a diagnostic challenge for clinicians. Employing a diagnostic algorithm as proposed may aid in the distinction of malignant and premalignant pathology and prevent unwarranted pancreatic resections.
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “Ten patients of 303 patients who underwent a distal pancreatectomy were identified with a final pathology of IPAS. The average age was 54 y, 80% were white, and 60% were male. Lesions ranged in size from 7 mm to 5.1 cm in largest diameter (mean 2.2 cm). Lesions were described as round, well-marginated, and enhancing masses within the pancreatic tail. Preoperative workup was variable in terms of imaging and laboratory testing. Diagnostic workups were examined and combined with multidisciplinary input to create a diagnostic algorithm.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “IPAS are the result of splenic tissue buds failing to fuse during embryologic development and are quite common, found in 10%-20% of individuals. Accessory splenic tissue is usually asymptomatic and found incidentally with the most common location in the splenic hilum. However, 10%-15% are found in the pancreatic tail where they pose a diagnostic predicament.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152
- On CT, IPAS appears as solid heteroge- neously enhancing masses, size averages 1-3 cm, and most commonly within 3 cm of the tail of the pancreas. Similarly, 90% of our patients had an enhancing distal mass with a mean maximum diameter less than 3 cm. The attenuation of accessory splenic tissue is similar to the spleen on arterial and venous phases, which was commented on in only two of the initial CT reports.
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “The heterogeneous enhancement on arterial phase is secondary to the differences in rate of blood flow between the red pulp and the white pulp of the spleen. Nonfunctioning PNETs are also hyperenhancing lesions on CT but with uniform or ring-like enhancement and greater enhancement on the venous phase.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “Metastatic disease represents 2%-5% of all malignant pancreatic tumors and usually arises from renal cell carcinoma, non-small cell lung cancer, and gastrointestinal carcinoma. Renal cell carcinoma usually presents as an enhancing lesion, whereas the other two are usually hypoattenuating but all typically correlate with the discovery of a primary tumor on CT.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152
- “Imaging features of a small tumor of the pancreatic tail should be compared to that of the spleen to rule out the possibility of an intrapancreatic accessory spleen.”
Imaging features of rare pancreatic tumors M. Barrala, S.A. Faraound, E.K. Fishman, A. Dohan, C. Pozzesserea, M.-A. Berthelina,P. Bazeries, M. Barat, C. Hoeffel, P. Soyer Diagnostic and Interventional Imaging (2016) (in press)
- “Intrapancreatic accessory spleen is the second location of accessory spleens accounting for 17% of all locations . It is usually located 3-4cm from the splenic hilum, adjacent to the pancreatic tail. Embryologically, acces- sory spleen is a result of failure of fusion of splenic tissue buds of the dorsal mesogastrium. Pathologically pancreatic accessory spleen has the same histological features than the main spleen, surrounded by a thin capsule.”
Imaging features of rare pancreatic tumors M. Barrala, S.A. Faraound, E.K. Fishman, A. Dohan, C. Pozzesserea, M.-A. Berthelina,P. Bazeries, M. Barat, C. Hoeffel, P. Soyer Diagnostic and Interventional Imaging (2016) (in press) - “On imaging, intrapancreatic accessory spleen appears as a less than 4 cm solid enhancing mass with a smooth, round, ovoid or minimally lobulated shape within the tail of the pancreas . The patterns of enhancement parallel those of the main spleen with an arterial serpiginous pattern followed by a homogeneous enhancement during the portal and late phases.”
Imaging features of rare pancreatic tumors M. Barrala, S.A. Faraound, E.K. Fishman, A. Dohan, C. Pozzesserea, M.-A. Berthelina,P. Bazeries, M. Barat, C. Hoeffel, P. Soyer Diagnostic and Interventional Imaging (2016) (in press)
- “CT can be used to differentiate between IPAS and PanNETwith good specificity and sensitivity. The IPAS mirrors the spleen’s enhancement and is usually located along the dorsal surface of the pancreas.”
Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
Coquia SF,Kawamoto S, Hruban RH, Fishman EK
J Comput Assist Tomogr 2014 (in press) - “Although not statistically significant, several other findings are also helpful to differentiate IPAS and neuroendocrine tumors. All IPASs in this study were located at the tip or within 3 cm of the tip of the tail of the pancreas. Therefore, if an enhancing mass is een more than several centimeters from the tip of the tail of the pancreas, it is less likely to represent IPAS and more likely a neuroendocrine tumor.”
Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
Coquia SF,Kawamoto S, Hruban RH, Fishman EK
J Comput Assist Tomogr 2014 (in press) - “ In conclusion, CT can be used to differentiate between IPASs and PanNETs with a high degree of sensitivity and specificity. Specific findings on CT are more prevalent with IPASs and can help increase diagnostic conf idence. These f indings include a lesion that is not completely embedded in the pancreatic parenchyma, a lesion that is located along the dorsal surface of the pancreas, a lesion that shows heterogeneous enhancement at the arterial phase, and a lesion that has the same degree of en- hancement of the spleen at the venous phase.”
Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
Coquia SF,Kawamoto S, Hruban RH, Fishman EK
J Comput Assist Tomogr 2014 (in press) - “The reader should look for enhancement of the IPAS matching the enhancement pat- tern of the spleen on multiphase CT examination. Furthermore, routine evaluation of the splenic vein should be performed with each lesion as occlusion of the vein has been associated with non- functioning PanNETs.”
Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
Coquia SF,Kawamoto S, Hruban RH, Fishman EK
J Comput Assist Tomogr 2014 (in press) - “In cases where the reader finds the lesion as indeterminate, although most were ultimately PanNETs in our study, given the associated decline in overall reader specificity seen in our study, the CT reader should recommend confirmatory testing such as 99mTc-labeled heat-damaged red blood cell scintigraphy or MRI rather than an observation with fine needle aspiration as needed for confirmatio.”
Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
Coquia SF,Kawamoto S, Hruban RH, Fishman EK
J Comput Assist Tomogr 2014 (in press)
- “ Intrapancreatic accessory spleen (IPAS) should be considered when a hypervascular mass is seen in the tail of the pancreas on CT. Typical location, similar attenuation of the lesion to the spleen on noncontrast, and postcontrast CT at different phases are helpful to make diagnosis of IPAS.”
Intrapancreatic accessory spleen: CT appearance and differential diagnosis
Kawamoto S, Johnson PT, Hull H, Cameron JL, Hruban RH, Fishman EK
Abdom Imaging (2012)37:812-827 - “ In autopsy studies, the second most common site of accessory spleen is the tail of the pancreas.”
Intrapancreatic accessory spleen: CT appearance and differential diagnosis
Kawamoto S, Johnson PT, Hull H, Cameron JL, Hruban RH, Fishman EK
Abdom Imaging (2012)37:812-827 - Intrapancreatic Accessory Spleen: CT Findings
CT attenuation and enhancement pattern
- Similar enhancement on noncontrast and postcontrast scans
- Arterial phase enhancement is similar to the spleen including the serpiginous pattern of enhancement - Intrapancreatic Accessory Spleen: Differential Dx
- Neuroendocrine tumor (NETs)
- Metastatic renal cell carcinoma to the pancreas
- Splenic artery aneurysm - “ However, when it remains difficult to exclude the other diagnosis, 99m-Tc labeled HDRBC scintigraphy or SPIO-enhanced MR imaging can be used to confirm the diagnosis of IPAS, with the caveats described above.”
Intrapancreatic accessory spleen: CT appearance and differential diagnosis
Kawamoto S, Johnson PT, Hull H, Cameron JL, Hruban RH, Fishman EK
Abdom Imaging (2012)37:812-827
- Epidermoid cyst in intrapancreatic accessory spleen
- 1. Cyst lined by stratified squamous epithelium.
- 2. Dozens of case reports.
- 3. Squamous-lined cysts of the pancreas: lymphoepithelial cysts, dermoid cysts,[ teratomas ], and accessory-splenic epidermoid cysts. Adsay NV et al. Semin Diagn Pathol. 2000 ; 17: 56-65. [ Wayne State.