P2765 - A Wandering Accessory Spleen Mimicking a Pancreatic Tumor

Peter H. Nguyen, MD¹, Vamsi Vemireddy, MD², Neil R. Jariwalla, MD², Emily Bernal, ³, Alexa Truong, BS², Jason Samarasena, MD^4
1University of California Irvine, Orange, CA; ²University of California Irvine Medical Center, Orange, CA; ³H. H. Chao Comprehensive Digestive Disease Center, University of California Irvine, Orange, CA; ⁴University of California - Irvine, Orange, CA

Introduction: Pancreatic masses can have a varied differential ranging from adenocarcinomas to pre-cancerous tumors or benign tumor-like lesions. One such tumor-like lesion is the accessory spleen. An accessory spleen is found in 10-15% of patients and occurs most commonly in the perihilar region of the spleen (80%) followed by the tail of the pancreas. This is a case of a pancreatic mass initially thought to be a neuroendocrine tumor found to be an accessory spleen.

Case Description/Methods: A 71 year old female presented to her primary care provider with abdominal pain and CT findings of a 1.6 cm mass in the pancreatic body. The patient was referred to gastroenterology for endoscopic ultrasound (EUS) with fine needle aspiration (FNA). On EUS, a 1.2 cm x 1.6 cm hypoechoic round lesion was identified in the body of the pancreas (Figure 1). The imaging findings were consistent with a T1 pancreatic neuroendocrine tumor and subsequently biopsied by FNA. The pathology report showed no malignant cells and found small fragments of lymphoid tissue. The patient had a repeat EUS with FNA 3 months later. The mass was again visualized in the body of the pancreas. Pathology report found CD8 positive cells, forming vascular-like channels suggesting splenic tissue. The patient returned 6 months later for a repeat EUS with FNA since it was unclear if the mass was an accessory spleen given the large distance away from the spleen on EUS imaging. The mass unchanged and again the mass appeared to arise from the pancreas and on EUS it had the same echogenicity as the spleen. This biopsy was negative for neuroendocrine and epithelial markers and showed the same CD8 positive cells lining vascular channels suggestive of splenic tissue. The patient was reassured she did not have a malignancy and it was a benign finding of an accessory spleen.



Discussion: A pancreatic mass found on imaging would raise concerns for malignancy yet the differential remains broad including more benign masses. An accessory spleen is most commonly found in the perihilar region of the spleen, but is next commonly found near the tail of the pancreas. This case, initially thought to be a neuroendocrine tumor which would require surgery, was found to be an accessory spleen avoiding an invasive procedure and reassuring for the patient. It is important to consider accessory spleen on the differential diagnosis when evaluating a pancreatic mass.


Figure: Initial EUS showing a 1.2 cm x 1.6 cm hypoechoic pancreatic mass


Disclosures:
Peter Nguyen indicated no relevant financial relationships.
Vamsi Vemireddy indicated no relevant financial relationships.
Neil Jariwalla indicated no relevant financial relationships.
Emily Bernal indicated no relevant financial relationships.
Alexa Truong indicated no relevant financial relationships.
Jason Samarasena: Conmed – Consultant. Cook Medical – Grant/Research Support. Olympus – Consultant.


Peter H. Nguyen, MD¹, Vamsi Vemireddy, MD², Neil R. Jariwalla, MD², Emily Bernal, ³, Alexa Truong, BS², Jason Samarasena, MD⁴. P2765 - A Wandering Accessory Spleen Mimicking a Pancreatic Tumor, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.