INTERESTING IMAGE
Intrapancreatic Accessory Spleen Detected by 68Ga DOTANOC PET/CT and 99mTc-Colloid SPECT/CT Scintigraphy Angela Collarino, MD,* Annemilia del Ciello, MD,† Germano Perotti, MD,* and Vittoria Rufini, MD* Abstract: A 77-year-old man was referred to our center for a suspected neuroendocrine neoplasm in the pancreatic tail, incidentally detected at CT. 68Ga DOTANOC PET/CT showed intense tracer uptake in the pancreatic lesion. At MRI, the lesion was similar to the spleen on all sequences, suggesting the presence of intrapancreatic accessory spleen. A 99mTc-colloid SPECT/CT scan performed to differentiate spleen tissue from neuroendocrine tumor revealed a focal uptake in the pancreatic lesion, thus confirming the presence of ectopic spleen and avoiding unnecessary surgery. Key Words: intrapancreatic accessory spleen, 68Ga DOTANOC PET/CT, 99m Tc-colloid SPECT/CT (Clin Nucl Med 2015;40: 415–418)
Received for publication April 30, 2014; revision accepted August 21, 2014. From the *Institute of Nuclear Medicine, and †Institute of Radiology, Università Cattolica del Sacro Cuore, Rome, Italy. Conflicts of interest and sources of funding: none declared. Reprints: Angela Collarino, MD, Largo Agostino Gemelli, 8 00168 Rome (RM), Italy. E-mail: [email protected]. Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0363-9762/15/4005–0415
ACKNOWLEDGMENTS The authors would like to thank Massimo Falconi, MD, for reporting the patient. REFERENCES 1. Halpert B, Gyorkey F. Lesions observed in accessory spleens of 311 patients. Am J Clin Pathol. 1959;32:165–168. 2. Eraklis AJ, Filler RM. Splenectomy in childhood: a review of 1413 cases. J Pediatr Surg. 1972;7:382–388. 3. Halpert B, Alden ZA. Accessory spleens in or at the tail of the pancreas: a survey of 2,700 additional necropsies. Arch Pathol. 1964;77:652–654. 4. Kuyumcu S, Ozkan ZG, Sanli Y, et al. Physiological and tumoral uptake of 68GaDOTATATE: standardized uptake values and challenges in interpretation. Ann Nucl Med. 2013;27:538–554. 5. Lebtahi R, Cardiot G, Marmuse JP, et al. False-positive somatostatin receptor scintigraphy due to an accessory spleen. J Nucl Med. 1997;38:1979–1981. 6. Brasca LE, Zanello A, De Gaspari A, et al. Intrapancreatic accessory spleen mimicking a neuroendocrine tumor: magnetic resonance findings and possible diagnostic role of different nuclear medicine tests. Eur Radiol. 2004;14:1322–1323. 7. Spencer LA, Spizarny DL, Williams TR. Imaging features of intrapancreatic accessory spleen. Br J Radiol. 2010;83:668–673. 8. Kim SH, Lee JM, Han JK, et al. Intrapancreatic accessory spleen: findings on MR imaging, CT, US and scintigraphy, and the pathologic analysis. Korean J Radiol. 2008;9:162–174.
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Clinical Nuclear Medicine • Volume 40, Number 5, May 2015
FIGURE 1. A 77-year-old man underwent a contrast-enhanced CT scan of the thorax for better evaluating a lung nodule that had been reported by chest x-ray performed before carotid surgery. No lung parenchymal abnormalities were identified at CT; however, the upper abdominal scans showed a nodule in the pancreatic tail (white arrow). The nodule was ovoid with regular margins and a 2-cm maximum diameter. On contrast-enhanced axial CT image, the lesion demonstrated high enhancement, thus mimicking a pancreatic neuroendocrine neoplasm.
FIGURE 2. To assess the presence of somatostatin receptors in the pancreatic lesion, 68Ga DOTANOC PET/CT was performed. MIP (A) and transaxial fused images (B and C) showed intense tracer uptake in the known pancreatic lesion (white arrows), confirming high expression of somatostatin receptors (SUVmax, 29.7). 416
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© 2014 Wolters Kluwer Health, Inc. All rights reserved. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
Clinical Nuclear Medicine • Volume 40, Number 5, May 2015
Intrapancreatic Spleen Detected by Scintigraphy
FIGURE 3. MRI of the abdomen was performed before surgery. At axial images, the nodule in the pancreatic tail was mildly hyperintense on T2-weighted sequences (A) and hypointense on T1-weighted sequences (B). On gadolinium-enhanced MRI scan obtained during arterial phase, the lesion showed inhomogeneous enhancement similar to that of the spleen. The features on precontrast (C) and contrast-enhanced (D) images suggested the presence of splenic intrapancreatic tissue.
© 2014 Wolters Kluwer Health, Inc. All rights reserved. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
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417
Collarino et al
Clinical Nuclear Medicine • Volume 40, Number 5, May 2015
FIGURE 4. To confirm the splenic nature of the pancreatic nodule, a 99mTc-colloid scan was performed. Posterior planar (A) and transaxial fused SPECT/CT images (B and C) showed focal uptake in the pancreatic tail (white arrows), demonstrating the presence of intrapancreatic accessory spleen. Accessory spleens are congenital abnormalities of ectopic splenic tissue, found in 10% to 30% of patients at autopsy,1 with a 45% to 65% incidence in patients after splenectomy.2 Accessory spleens are usually located at or near the splenic hilum, with 20% of cases in the pancreatic tail or close to it.3 In our case, 68Ga DOTANOC PET/CT showed a focal intense tracer uptake in the pancreatic lesion, raising the question of differential diagnosis between neuroendocrine neoplasm and ectopic spleen. In fact, both well-differentiated neuroendocrine tumors and splenic tissue show intense uptake of somatostatin analogs4 because of the presence of somatostatin receptors on the surface of both tumor cells and splenic lymphocytes.5 99mTc-labeled colloids are taken up in the liver and spleen, due to phagocytosis in reticulum-endothelial cells, and can identify splenic ectopic tissue.6,7 The added value of SPECT/CT is well known, allowing precise lesion localization and better functional characterization. In our case, 99mTc-colloid SPECT/ CT was very useful to confirm the diagnostic suspect of intrapancreatic accessory spleen, thus avoiding unnecessary surgical procedures and decreasing overall patient morbidity.8
418
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© 2014 Wolters Kluwer Health, Inc. All rights reserved. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
Intrapancreatic Accessory Spleen Detected by 68Ga DOTANOC PET/CT and 99mTc-Colloid SPECT/CT Scintigraphy Angela Collarino, MD,* Annemilia del Ciello, MD,† Germano Perotti, MD,* and Vittoria Rufini, MD* Abstract: A 77-year-old man was referred to our center for a suspected neuroendocrine neoplasm in the pancreatic tail, incidentally detected at CT. 68Ga DOTANOC PET/CT showed intense tracer uptake in the pancreatic lesion. At MRI, the lesion was similar to the spleen on all sequences, suggesting the presence of intrapancreatic accessory spleen. A 99mTc-colloid SPECT/CT scan performed to differentiate spleen tissue from neuroendocrine tumor revealed a focal uptake in the pancreatic lesion, thus confirming the presence of ectopic spleen and avoiding unnecessary surgery. Key Words: intrapancreatic accessory spleen, 68Ga DOTANOC PET/CT, 99m Tc-colloid SPECT/CT (Clin Nucl Med 2015;40: 415–418)
Received for publication April 30, 2014; revision accepted August 21, 2014. From the *Institute of Nuclear Medicine, and †Institute of Radiology, Università Cattolica del Sacro Cuore, Rome, Italy. Conflicts of interest and sources of funding: none declared. Reprints: Angela Collarino, MD, Largo Agostino Gemelli, 8 00168 Rome (RM), Italy. E-mail: [email protected]. Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0363-9762/15/4005–0415
ACKNOWLEDGMENTS The authors would like to thank Massimo Falconi, MD, for reporting the patient. REFERENCES 1. Halpert B, Gyorkey F. Lesions observed in accessory spleens of 311 patients. Am J Clin Pathol. 1959;32:165–168. 2. Eraklis AJ, Filler RM. Splenectomy in childhood: a review of 1413 cases. J Pediatr Surg. 1972;7:382–388. 3. Halpert B, Alden ZA. Accessory spleens in or at the tail of the pancreas: a survey of 2,700 additional necropsies. Arch Pathol. 1964;77:652–654. 4. Kuyumcu S, Ozkan ZG, Sanli Y, et al. Physiological and tumoral uptake of 68GaDOTATATE: standardized uptake values and challenges in interpretation. Ann Nucl Med. 2013;27:538–554. 5. Lebtahi R, Cardiot G, Marmuse JP, et al. False-positive somatostatin receptor scintigraphy due to an accessory spleen. J Nucl Med. 1997;38:1979–1981. 6. Brasca LE, Zanello A, De Gaspari A, et al. Intrapancreatic accessory spleen mimicking a neuroendocrine tumor: magnetic resonance findings and possible diagnostic role of different nuclear medicine tests. Eur Radiol. 2004;14:1322–1323. 7. Spencer LA, Spizarny DL, Williams TR. Imaging features of intrapancreatic accessory spleen. Br J Radiol. 2010;83:668–673. 8. Kim SH, Lee JM, Han JK, et al. Intrapancreatic accessory spleen: findings on MR imaging, CT, US and scintigraphy, and the pathologic analysis. Korean J Radiol. 2008;9:162–174.
Clinical Nuclear Medicine • Volume 40, Number 5, May 2015 Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.nuclearmed.com
415
Collarino et al
Clinical Nuclear Medicine • Volume 40, Number 5, May 2015
FIGURE 1. A 77-year-old man underwent a contrast-enhanced CT scan of the thorax for better evaluating a lung nodule that had been reported by chest x-ray performed before carotid surgery. No lung parenchymal abnormalities were identified at CT; however, the upper abdominal scans showed a nodule in the pancreatic tail (white arrow). The nodule was ovoid with regular margins and a 2-cm maximum diameter. On contrast-enhanced axial CT image, the lesion demonstrated high enhancement, thus mimicking a pancreatic neuroendocrine neoplasm.
FIGURE 2. To assess the presence of somatostatin receptors in the pancreatic lesion, 68Ga DOTANOC PET/CT was performed. MIP (A) and transaxial fused images (B and C) showed intense tracer uptake in the known pancreatic lesion (white arrows), confirming high expression of somatostatin receptors (SUVmax, 29.7). 416
www.nuclearmed.com
© 2014 Wolters Kluwer Health, Inc. All rights reserved. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
Clinical Nuclear Medicine • Volume 40, Number 5, May 2015
Intrapancreatic Spleen Detected by Scintigraphy
FIGURE 3. MRI of the abdomen was performed before surgery. At axial images, the nodule in the pancreatic tail was mildly hyperintense on T2-weighted sequences (A) and hypointense on T1-weighted sequences (B). On gadolinium-enhanced MRI scan obtained during arterial phase, the lesion showed inhomogeneous enhancement similar to that of the spleen. The features on precontrast (C) and contrast-enhanced (D) images suggested the presence of splenic intrapancreatic tissue.
© 2014 Wolters Kluwer Health, Inc. All rights reserved. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.nuclearmed.com
417
Collarino et al
Clinical Nuclear Medicine • Volume 40, Number 5, May 2015
FIGURE 4. To confirm the splenic nature of the pancreatic nodule, a 99mTc-colloid scan was performed. Posterior planar (A) and transaxial fused SPECT/CT images (B and C) showed focal uptake in the pancreatic tail (white arrows), demonstrating the presence of intrapancreatic accessory spleen. Accessory spleens are congenital abnormalities of ectopic splenic tissue, found in 10% to 30% of patients at autopsy,1 with a 45% to 65% incidence in patients after splenectomy.2 Accessory spleens are usually located at or near the splenic hilum, with 20% of cases in the pancreatic tail or close to it.3 In our case, 68Ga DOTANOC PET/CT showed a focal intense tracer uptake in the pancreatic lesion, raising the question of differential diagnosis between neuroendocrine neoplasm and ectopic spleen. In fact, both well-differentiated neuroendocrine tumors and splenic tissue show intense uptake of somatostatin analogs4 because of the presence of somatostatin receptors on the surface of both tumor cells and splenic lymphocytes.5 99mTc-labeled colloids are taken up in the liver and spleen, due to phagocytosis in reticulum-endothelial cells, and can identify splenic ectopic tissue.6,7 The added value of SPECT/CT is well known, allowing precise lesion localization and better functional characterization. In our case, 99mTc-colloid SPECT/ CT was very useful to confirm the diagnostic suspect of intrapancreatic accessory spleen, thus avoiding unnecessary surgical procedures and decreasing overall patient morbidity.8
418
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© 2014 Wolters Kluwer Health, Inc. All rights reserved. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
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