title: Collision tumor versus multiphenotypic differentiation: a case of carcinoma with features of colonic and lung primary tumors.
abstract: BACKGROUND
  Collision tumors are rare tumors composed of two histologically distinct neoplasms coinciding at the same location. Collision tumors need to be distinguished from tumors originating from a progenitor cell with potential for multiphenotypic differentiation.
  
  
  METHODS
  A clinically puzzling case of an intricate malignant pulmonary nodule in a patient with previous history of colorectal carcinoma is reported. A brief review of the clinical literature on collision tumor and tumor stem cells is presented.
  
  
  CONCLUSIONS
  This case report emphasizes the importance of detailed histopathologic and immunohistochemical analyses, and clinical history in diagnosing a tumor composed of multiple malignant morphologies.
authors.affiliation: Division of Hematology, Oncology and Transplantation, University of Minnesota, 420 Delaware Street SE, MMC 480 Minneapolis, MN 55455, U.S.A.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Murthaiah
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Truskinovsky
authors.forename: Saira
authors.initials: S
authors.lastname: Shah
authors.forename: Arkadiusz Z
authors.initials: AZ
authors.lastname: Dudek
mesh_terms: D000368:Aged; D002454:Cell Differentiation; D003110:Colonic Neoplasms / Q000473:pathology*; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D008297:Male; D010641:Phenotype