Intrapancreatic accessory spleen is a benign lesion that mimics hypervascular or cystic pancreatic neoplasm. A comprehensive clinicopathologic analysis has not yet been reported.
We described the clinicopathologic characteristics of 12 cases of pathologically proven intrapancreatic accessory spleen, among which 6 had internal epidermoid cysts. Immunohistochemistry was done to clarify the origin of epidermoid cysts.
Most cases were incidentally detected in young adults. Two-thirds of cases with intra-lesional cysts showed elevated serum carbohydrate antigen 19-9 levels. Radiologically, heterogeneously enhancing a solid portion similar to the spleen was a helpful, but not convincing, feature. Grossly, a well-circumscribed dark red mass with or without cysts in the pancreatic tail was characteristic. Microscopically, small foci of pancreatic tissue were embedded within the splenic tissue. Epidermoid cysts consisted of modified squamous epithelium, some of which had intracellular mucin. Cytologic smears showed large aggregates of benign spindle cells that were reactive against CD8. Immunohistochemical staining of the cystic epithelium suggested its pancreatic ductal origin.
Intrapancreatic accessory spleen with or without epidermoid cyst should be considered as differential diagnoses when well-enhanced solid or cystic tumors are found in the pancreatic tail. Radiologic suspicion and preoperative aspiration or biopsy might minimize the need for unnecessary surgery.
From the Departments of *Pathology, †Radiology and Research Institute of Radiology, ‡Surgery, and §Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
Received for publication January 28, 2011; accepted February 17, 2011.
Reprints: Jihun Kim, MD, PhD, Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Asanbyeongwon-gil 86, Songpa-gu, Seoul 138-736, South Korea (e-mail: firstname.lastname@example.org).
Supported by the Asan Institute for Life Sciences, Seoul, South Korea (grant 2010-483).