title: Interphase fluorescence in situ hybridization analysis of chromosome 12p abnormalities is useful for distinguishing epidermoid cysts of the testis from pure mature teratoma.
abstract: OBJECTIVE
  The distinction of epidermoid cyst of the testis from teratoma is of critical importance because the former is benign and the latter is a malignant tumor that may have associated metastasis of either teratomatous or non-teratomatous germ cell tumor types. Chromosome 12p abnormalities are seen in the vast majority of testicular germ cell tumors of adults and are present in all histologic subtypes. In this study, we investigated the clinical utility of interphase fluorescence in situ hybridization (FISH) analysis of chromosome 12p abnormalities for distinguishing epidermoid cysts of the testis from pure mature teratoma.
  
  
  METHODS
  Sixteen testicular epidermoid cysts and 17 testicular teratomas were investigated for isochromosome 12p [i(12p)] and 12p overrepresentation using interphase FISH analysis.
  
  
  RESULTS
  Neither i(12p) nor 12p overrepresentation were observed in 16 epidermoid cyst cases, whereas i(12p) was detected in 76% of teratomas and 12p overrepresentation was identified in 29% of teratomas. Overall, 88% of testicular teratomas had chromosome 12p abnormalities.
  
  
  CONCLUSIONS
  FISH identification of i(12p) and/or 12p overrepresentation in routinely processed surgical specimens is a useful ancillary diagnostic tool in distinguishing testicular epidermoid cysts from teratoma.
authors.affiliation: Departments of Pathology and Laboratory Medicine, Indiana University School of Medicine, 350 West 11th Street, Indianapolis, IN 46202, USA. lcheng@iupui.edu
authors.forename: Liang
authors.initials: L
authors.lastname: Cheng
authors.forename: Shaobo
authors.initials: S
authors.lastname: Zhang
authors.forename: Gregory T
authors.initials: GT
authors.lastname: MacLennan
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Poulos
authors.forename: Ming-Tse
authors.initials: MT
authors.lastname: Sung
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Beck
authors.forename: Richard S
authors.initials: RS
authors.lastname: Foster
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics*; D004814:Epidermal Cyst / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007399:Interphase; D007621:Karyotyping; D008297:Male; D013724:Teratoma / Q000235:genetics*; D013736:Testicular Neoplasms / Q000235:genetics*; D014407:Tumor Cells, Cultured