Laparoscopic distal pancreatectomy for intrapancreatic accessory spleen: a case report

Abstract

Accessory spleen is a congenital anomaly of splenic tissue found outside the spleen. It is present in 10% of the population and may occur throughout the entire abdominal cavity. Roughly 20% of accessory spleens are located within the pancreatic tail. Intrapancreatic accessory spleen (IPAS) provides a diagnostic dilemma during the work-up of patients with pancreatic tail lesions. Their radiological presence often imitates that of a pancreatic neuroendocrine tumour (PNET). Confirmation of an IPAS typically occurs through histopathological examination, following surgical resection for a presumed PNET. A 55-year-old male presented with chest and epigastric pain. Blood tests demonstrated mixed liver function tests (ALP of 164 U/L, GGT of 1126 U/L, AST of 775 U/L, ALT of 689 U/L, bilirubin of 44 U/L) and normal inflammatory markers. Initial imaging with abdominal ultrasound (US) showed a thickened gall bladder wall and cholelithiasis. Magnetic resonance cholangiopancreatography (MRCP) confirmed choledocolithiasis and an incidental pancreatic tail lesion. Pancreatic-protocol magnetic resonance imaging (MRI) confirmed the existence of a pancreatic tail lesion demonstrating intense enhancement in both early and late arterial phases, which was highly suggestive of a PNET (Fig. 1). On computed tomography (CT) imaging, the lesion demonstrated arterial and portal venous enhancement, measuring 1.6 cm in diameter, with no evidence of local spread or distant metastatic disease (Fig. 2). Gallium DOTATATE positron emission tomography (Ga-DOTATATE PET) was performed, with intense tracer uptake localized to the pancreatic tail, suggestive of a well differentiated somatostatin receptor-positive neuroendocrine tumour. No regional nodal or distant spread was detected. The patient was discussed at a multi-disciplinary meeting and proceeded to a laparoscopic spleenpreserving distal pancreatectomy. Macroscopically, the distal pancreas contained a circumscribed dark brown to red nodule, 11 × 8 × 20 mm in dimension. The remaining pancreatic tissue was unremarkable. Microscopic examination of the tissue revealed the nodule to be a focus of heterotopic spleen (Fig. 3). Despite the radiographic similarities between IPAS and hypervascular pancreatic tumours, several distinguishing features on various imaging modalities assist in differentiation. On CT, IPAS most commonly displays heterogeneous contrast enhancement during arterial phase, due to the different flow rates between the red and white pulp of splenic tissue, and can be identified by