Non-neoplastic pancreatic lesions that may mimic malignancy

Intrapancreatic Accessory Spleen: A Diagnosis Not to Forget!

“…Radiologically, an IPAS tends to be a small, round, and homogeneous lesion with well-defined borders and is usually located within the pancreatic tail. Its hypervascular nature and imaging characteristics similar to the adjacent spleen may support the diagnosis [7]. Therefore, imaging studies should be contrast-enhanced and should parallel the spleen.…”

“…This is due to the presence of somatostatin receptors in IPAS lymphocytes, which also have a high affinity to octreotide, therefore mimicking a pancreatic NET. Moreover, around 30–40% of the pancreatic NET are nonfunctioning and present normal hormone levels, further complicating the differential diagnosis from IPAS [1, 7]. Other imaging modalities that have been proven to help identify IPAS include 99m Tc-sulfur colloid scintigraphy and contrast-enhanced EUS [2].…”

“…Consequently, many patients are still misdiagnosed as having a pancreatic neoplasm and undergo an unnecessary pancreatic resection [2, 7]. Indeed, about 1–5% of the pancreatectomies performed with the primary diagnosis of pancreatic carcinomas are later proved to be nonneoplastic, space-occupying lesions [11, 12].…”

“…Fortunately, this percentage is decreasing with the improved radiologic and endoscopic sampling diagnostic capabilities, in particular with EUS-FNA. EUS-FNA has been demonstrated to be a safe and effective tool to obtain a definitive IPAS diagnosis [1, 2, 7, 8, 9, 10, 11, 12, 13]. In the largest study of IPAS diagnosis established using EUS-FNA, this technique was successful in 90% of the cases, and no complications were reported [9].…”

“…The cytologic features of the splenic tissue are characterized by small lymphocytes with a mixed inflammatory infiltrate with the appearance of the white pulp and presence of thin-walled blood vessels, which represent the splenic sinuses. When a cell block or histology is available, confirmation by CD8 immunohistochemical staining, a commonly used T-cell marker that is taken up by endothelial cells of the splenic sinus, is recommended [2, 7]. This stain is highly specific, since systemic endothelial cells and hemagioma are negative [1].…”