Epidermoid Cysts in an Intrapancreatic Accessory Spleen Mimicking Pancreatic Neoplasms: Two Case Reports and a Literature Review of Japanese Cases.

INTRODUCTION: Epidermoid cyst(s) arising in an intrapancreatic accessory spleen (ECIPAS) are rare benign lesions that often mimic pancreatic cystic neoplasms on imaging studies. Owing to their rarity and nonspecific radiological features, ECIPAS are frequently misdiagnosed preoperatively, leading to unnecessary pancreatic resections.

CASE PRESENTATION: We report 2 asymptomatic middle-aged women who were incidentally found to have cystic lesions in the tail of the pancreas during routine imaging examinations. Contrast-enhanced CT and MRI demonstrated well-demarcated cystic lesions with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. In both cases, mucinous cystic neoplasms or intraductal papillary mucinous neoplasms were suspected, prompting distal pancreatectomies, with a concomitant splenectomy in 1 patient. Histopathological examination revealed cysts lined predominantly by stratified squamous epithelium and surrounded by normal splenic tissue, confirming the diagnosis of ECIPAS. In addition, a review of the Japanese literature identified 52 reported cases of ECIPAS; most patients were asymptomatic, with lesions predominantly located in the pancreatic tail and frequently associated with elevated serum carbohydrate antigen 19-9 levels, although normal levels are also common.

CONCLUSIONS: Recognizing ECIPAS may support more cautious clinical decision-making and help surgeons consider less invasive management strategies, including spleen-preserving distal pancreatectomy when appropriate.