title: CK19 is a sensitive marker for yolk sac tumours of the testis.
abstract: BACKGROUND
  Malignant germ cell tumours are the most common malignant tumours in young men. They are histologically divided into seminomas and non-seminomas. Non-seminomas are further subdivided into embryonic carcinomas, yolk sac tumours, chorionic carcinomas, and teratomas. For the therapeutic management it is essential to differentiate between these histological subtypes.
  
  
  METHODS
  Investigated cases included normal testis (n = 50), intratubular germ cell neoplasia (n = 25), seminomas (n = 67), embryonic carcinomas (n = 56), yolk sac tumours (n = 29), chorionic carcinomas (n = 2), teratomas (n = 7) and four metastases of YST's for their CK19 expression. In addition Leydig cell- (n = 10) and Sertoli cell- tumours (n = 4) were included in this study.
  
  
  RESULTS
  All investigated seminomas, embryonic carcinomas as well as normal testis and intratubular germ cell neoplasias did not express CK19. In contrast, all investigated yolk sac tumours strongly expressed CK19 protein. These findings became also evident in mixed germ cell tumours consisting of embryonic carcinomas and yolk sac tumours, although CK19-expression could also be observed in analysed chorionic carcinomas and epithelial components of teratomas.
  
  
  CONCLUSIONS
  CK19 proved to be a sensitive marker to identify yolk sac tumours of the testis and to distinguish them from other germ cell tumours, especially seminomas and embryonic carcinomas.
  The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/4075546891400979.
authors.affiliation: Institute of Pathology, University Medical Center, University of Göttingen, Göttingen, Germany. felix.bremmer@med.uni-goettingen.de.
authors.forename: Felix
authors.initials: F
authors.lastname: Bremmer
authors.affiliation: Institute of Pathology, University Medical Center, University of Göttingen, Göttingen, Germany. philipp.stroebel@med.uni-goettingen.de.
authors.forename: Philipp
authors.initials: P
authors.lastname: Ströbel
authors.affiliation: University Medical Center, University of Göttingen, Göttingen, Germany. hubjarry@med.uni-goettingen.de.
authors.forename: Hubertus
authors.initials: H
authors.lastname: Jarry
authors.affiliation: Institute of Pathology, University Medical Center, University of Göttingen, Göttingen, Germany. jasmin.strecker@stud.uni-goettingen.de.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Strecker
authors.affiliation: Institute of Pathology, RWTH Aachen University, Aachen, Germany. ngaisa@ukaachen.de.
authors.forename: Nadine
authors.initials: N
authors.lastname: Gaisa
authors.affiliation: Department of Urology, University Medical Center, University of Göttingen, Göttingen, Germany. astrauss@med.uni-goettingen.de.
authors.forename: Arne
authors.initials: A
authors.lastname: Strauß
authors.affiliation: Gemeinschaftspraxis Pathologie, Starnberg, Germany. S.Schweyer@pathologie-starnberg.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schweyer
authors.affiliation: Institute of Pathology, University Medical Center, University of Göttingen, Göttingen, Germany. hradzun@med.uni-goettingen.de.
authors.forename: Heinz-Joachim
authors.initials: HJ
authors.lastname: Radzun
authors.affiliation: Institute of Pathology, University Medical Center, University of Göttingen, Göttingen, Germany. clbehnes@med.uni-goettingen.de.
authors.forename: Carl-Ludwig
authors.initials: CL
authors.lastname: Behnes
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D003937:Diagnosis, Differential; D018240:Endodermal Sinus Tumor / Q000737:chemistry* / Q000473:pathology / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D053539:Keratin-19 / Q000032:analysis*; D008297:Male; D009919:Orchiectomy; D013736:Testicular Neoplasms / Q000737:chemistry* / Q000473:pathology / Q000601:surgery
chemical_list: D014408:Biomarkers, Tumor; D053539:Keratin-19