Endoscopic Ultrasound-Guided, Needle-Based Probe Confocal Laser Endomicroscopy (nCLE) of Intrapancreatic Accessory Spleen: Case Report and Literature Review

Abstract

Introduction: Accessory spleens are often incidental findings on imaging and usually present as a solid mass at splenic hilum or other organs such as pancreas. Most patients with accessory spleens are asymptomatic however abdominal pain has been associated with an accessory spleen. Intrapancreatic accessory spleen (IPAS) can mimic a pancreatic neuroendocrine tumor (NET) on imaging studies and therefore posing a diagnostic dilemma. We present a case of IPAS in which the concomitant use of nCLE and fine needle aspiration (FNA) helped make the diagnosis. A 24 year old female referred for EUS for a pancreatic mass on CT scan. She presented with abdominal pain and during the workup a 3cm x 2.9cm round hypervascular hypodense mass in the tail of the pancreas was found. Her past medical history is significant for second degree relative with pancreatic cancer. Patient has a past medical history of Thrombotic Thrombocytopenic Purpura (TTP) and she underwent splenectomy 5 years ago for profound thrombocytopenia. On EUS a 2.8cm x 2.9cm round homogenous hypoechoic mass in pancreatic tail was identified. Initially the mass was punctured using a 19-G needle that was pre-loaded with AQ-Flex 19 probe inside the needle before puncture in lieu of the stylet. Fluorescein (2.5mL of 10 % fluorescein sodium) was injected simultaneously with probe insertion. Numerous thick white bands with floating small black particles inside the bands suggestive of network of blood vessels and floating Erythrocytes. Interrogation of the mass did not identify any finger-like papillary projections, crypt-like structures or dark aggregates of cells which is seen in a villous structure or neoplastic cells. Then 4 passes using a 22 G FNA needle was performed with onsite pathology and endomicroscopy review supported the final diagnosis of IPAS. Discussion: Accessory spleen is a rare entity which can be seen in the splenic hilum or at the tail of the pancreas. In 3000 autopsies reported by Halpert et al, 364 accessory spleens were found in which 17% were IPAS. Accessory spleens can be acquired entities (splenosis) which is the auto transplantation of splenic tissue in abnormal locations as a result of trauma or post splenectomy. This is the first case that incorporates real-time endomicroscopy and onsite pathology to diagnose IPAS. Patients with IPAS may undergo distal pancreatectomy because they mimic a hypervascular NET on CT and MRI scans. Onsite pathology and endomicroscopy review increases the diagnostic accuracy for differentiating between IPAS and pancreatic NET. In patients with a hypervascular mass in the tail of pancreas addition of real time nCLE to traditional FNA can increase the diagnosis yield of EUS and potentially prevent unnecessary surgery.Figure 1Figure 2Figure 3