title: Solid pseudopapillary neoplasm collides with a well-differentiated pancreatic endocrine neoplasm in an adult man: case report and review of histogenesis.
abstract: OBJECTIVE
  Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare, clinicopathologically distinct neoplasm with a tendency to affect young women. The histogenesis of SPN is not well defined. Pancreatic endocrine neoplasms (PENs) are also uncommon tumors of the pancreas.
  
  
  METHODS
  Our comprehensive review of the literature did not yield any reported cases of collision tumors of the above two neoplasms. We report a case of such a collision tumor in a 45-year-old man.
  
  
  RESULTS
  This tumor was an incidental finding on computed tomography, followed by fine-needle aspiration confirmation of a tumor that was initially diagnosed as an SPN only. A histologic examination of a 2.1-cm mass following distal pancreatectomy revealed a 0.7-cm PEN partly engulfed by an SPN. The tumors showed different morphologic and immunohistochemical features, confirming the presence of a collision tumor.
  
  
  CONCLUSIONS
  A comparative analysis of immunoprofiles of these tumors yielded interesting findings, enabling us to postulate that SPNs may originate from a multipotential primordial cell that may follow different differentiation pathways, such as endocrine, epithelial, and acinar. The ultrastructures and immunophenotypic characteristics appear to support this hypothesis.
authors.affiliation: From the Department of Pathology, UT Southwestern Medical Center, Dallas, TX.
authors.forename: Shirley X
authors.initials: SX
authors.lastname: Yan
authors.affiliation: Department of Pathology, Baylor University Medical Center, Dallas, TX.
authors.forename: Carol F
authors.initials: CF
authors.lastname: Adair
authors.affiliation: From the Department of Pathology, UT Southwestern Medical Center, Dallas, TX.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Balani
authors.affiliation: Department of Surgery, UT Southwestern Medical Center, Dallas, TX.
authors.forename: John C
authors.initials: JC
authors.lastname: Mansour
authors.affiliation: From the Department of Pathology, UT Southwestern Medical Center, Dallas, TX.
authors.forename: Sefik T
authors.initials: ST
authors.lastname: Gokaslan
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D002291:Carcinoma, Papillary / Q000473:pathology*; D004701:Endocrine Gland Neoplasms / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018193:Neoplasms, Complex and Mixed / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor
keywords: Collision tumor; Pancreatic endocrine neoplasm; Solid pseudopapillary neoplasm; Solid pseudopapillary tumor