An unusual presentation of accessory spleen mimicking a pancreatic neoplastic lesion in a splenectomized patient: A case report.

Accessory spleen is a relatively common occurrence. However, an intrapancreatic accessory spleen can get hypertrophied following splenectomy and rarely mimic a pancreatic neoplasm leading to misdiagnosis. Here we present a 64-year-old male who had undergone left radical nephrectomy and splenectomy for renal cell carcinoma 14 years back, presenting with upper abdominal discomfort. He was found to have a mass in the pancreatic tail on imaging, suggesting an intrapancreatic neoplastic lesion. After a multidisciplinary team decision based on contrast-enhanced computed tomography and magnetic resonance imaging, he underwent an uncomplicated distal pancreatectomy, and the histology revealed an intrapancreatic accessory spleen. Contrast-enhanced computed tomography, magnetic resonance imaging, and positron emission tomography alone is not specific enough to confidently differentiate an accessory spleen preoperatively. Nuclear scintigraphy fused with contrast-enhanced computed tomography provides more specific and better anatomically localized evidence. Ultrasound-guided fine needle sampling showing lymphocytes with subsets of histiocytes, plasma cells, and immunohistochemistry showing CD8 positivity can be used to guide the definitive diagnosis. Differentiating an accessory spleen from a pancreatic neoplasm may be challenging preoperatively. Accessory spleen needs to be considered in the differential diagnosis of upper abdominal masses especially in patients who have undergone splenectomy.