Case of the Month 2016-07, Page 4

Answer: B) 99mTc sulfur colloid scintigraphy and C) 99mTc HDRBC scintigraphy

Both studies can be used to diagnose ectopic splenic tissue. 99mTc sulfur colloid is more commonly used and is less time-consuming, however 99m Tc labeled HDRBC has higher sensitivity for splenic tissue detection due to reduced uptake by normal liver tissue and bone marrow, thus improving target-to-background ratio. No uptake should be seen in neuroendocrine tumors or metastases with either study.

Octreoscans are used in the detection of neuroendocrine tumors but can result in false positive results in this case due to the presence of somatostatin receptors within splenic tissues.

For larger images, please click on Epigastric 7 , Epigastric 8   and Epigastric 9 .

Tc 99m sulfur colloid scintigraphy was performed. Planar views of the abdomen were obtained along with SPECT-CT fusion images demonstrating moderate radiotracer uptake in the pancreatic tail mass, confirming the diagnosis of an intrapancreatic accessory spleen.

Clinical Course

The gastroenterology service was consulted, and the patient underwent an EGD and EUS which demonstrated a well-circumscribed structure at the tail of the pancreas posteriorly, nearby the splenic hilum. It had the same echodensity at the spleen, compatible with an accessory spleen. Diffuse changes of the pancreas were also noted, suggestive of chronic pancreatitis.

The intrapancreatic accessory spleen was felt to be an incidental finding and unlikely related to the patient’s reported pain. The patient was started on pancrelipase for chronic pancreatitis and was found to be tolerating a diet with pain resolving at time of discharge.

Intrapancreatic Accessory Spleen (IPAC)

  • Congenital, can be found within the embryologic dorsal mesentery of the stomach and pancreas
  • Most commonly found in the splenic hilum with 20% found in or near the pancreatic tail
  • Usually asymptomatic, occasionally become symptomatic due to torsion, spontaneous rupture, hemorrhage and cyst formation
  • Differential diagnoses include hypervascular pancreatic tumors, particularly neuroendocrine tumors
  • Imaging features:
    • Most often small (1-3 cm), well-defined lesions
    • On CT and MRI, IPAS matches the density/intensity of the spleen on all contrast phases and sequences
    • Heterogenous enhancement can be seen on early phase images due to different rates of flow through the cords of red and white pulp (same as normal spleen)
    • Typically higher attenuation than the pancreas on all phases
    • Diagnosis can be confirmed by MRI with ferumoxides or nuclear medicine (99m Tc –HDRBC or 99m Tc –SC scintigraphy)
    • Usually require no treatment - therefore an accurate diagnosis is important to prevent unnecessary surgical resection or biopsy!

References


Kim, S.H., Lee, J.M., Han, J.K., Lee, J.Y, Kim, K.W, Cho, K.C., Choi, B.I. Intrapancreatic accessory spleen: Findings on MR imaging, CT, US and scintigraphy, and the pathologic analysis. Korean J Radiol. 2008 Mar-Apr; 9(2): 162-174.

Lehtinen, S.J., Schammel, C.M., Devane, M., Trocha, S.D. Intrapancreatic accessory spleen presenting as a pancreatic mass. J Gastrointestinal Oncology. 2013 Dec; 4(4)

Sica, G.T., Reed, M.F. Case 27: Intrapancreatic accessory spleen. Radiology 2000; 217:134-137.

Spencer, L.A., Spizamy, D.L., Williams, T.R. Imaging features of intrapancreatic accessory spleen. Br J Radiol. 2010 Aug; 83(992):668-673

Toure, L., Bedard, J., Sawan, B., Mosimann, F. Intrapancreatic accessory spleen mimicking a pancreatic endocrine tumour. Can J. Surg. 2010 Feb; 53(1): E1-E2

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