title: Intrapancreatic accessory spleen: clinicopathologic analysis of 12 cases.
abstract: OBJECTIVE
  Intrapancreatic accessory spleen is a benign lesion that mimics hypervascular or cystic pancreatic neoplasm. A comprehensive clinicopathologic analysis has not yet been reported.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Hee Sang
authors.initials: HS
authors.lastname: Hwang
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Lee
authors.forename: Song Cheol
authors.initials: SC
authors.lastname: Kim
authors.forename: Dong Wan
authors.initials: DW
authors.lastname: Seo
authors.forename: Jihun
authors.initials: J
authors.lastname: Kim
mesh_terms: D000328:Adult; D016827:CD8 Antigens / Q000378:metabolism; D002828:Choristoma / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D003937:Diagnosis, Differential; D004814:Epidermal Cyst / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010181:Pancreatic Cyst / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D010182:Pancreatic Diseases / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000175:diagnosis; D013154:Spleen
chemical_list: D016827:CD8 Antigens; D007633:Keratins