title: Nasopharyngeal carcinoma in situ: two cases of an emerging diagnostic entity.
abstract: BACKGROUND
  The association of Epstein-Barr virus (EBV) with the oncogenesis of nasopharyngeal carcinoma (NPC) is well established. Latent infection by EBV with clonal proliferation has also been demonstrated in preinvasive lesions of NPC. In situ hybridization for EBV-encoded RNA (ISH EBER) now serves as an ancillary test in the definitive diagnosis of these lesions.
  
  
  METHODS
  Two cases of nasopharyngeal carcinoma in situ (NPCIS) are presented in this study. Their biopsies were studied by ordinary light microscopy, the ISH EBER technique, and immunostaining for bcl-2. Tissue samples from 100 high risk subjects negative for NPC and NPCIS, who served as controls, were also studied using the ISH EBER technique.
  
  
  RESULTS
  NPCIS was characterized by abnormal light microscopic appearance as well as positive staining by the ISH EBER technique; these features were not observed in samples from the 100 high risk subjects. Immunostaining for bcl-2 protein was positive but less specific. Postradiotherapy biopsies of the two patients were negative for NPCIS.
  
  
  CONCLUSIONS
  With the help of the ISH EBER technique, the diagnosis of NPCIS is now possible in routine surgical pathology. As this entity is rare, it is necessary to have a high degree of suspicion when evaluating biopsies from high risk individuals. Radiotherapy for patients with NPCIS is justified in view of the risk of cancer progression and the possibility of a coexisting invasive carcinoma.
authors.affiliation: Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, People's Republic of China.
authors.forename: F
authors.initials: F
authors.lastname: Cheung
authors.forename: S W
authors.initials: SW
authors.lastname: Pang
authors.forename: F
authors.initials: F
authors.lastname: Hioe
authors.forename: K N
authors.initials: KN
authors.lastname: Cheung
authors.forename: A
authors.initials: A
authors.lastname: Lee
authors.forename: T K
authors.initials: TK
authors.lastname: Yau
mesh_terms: D002278:Carcinoma in Situ / Q000473:pathology* / Q000821:virology; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D006566:Herpesviridae Infections / Q000473:pathology / Q000821:virology; D004854:Herpesvirus 4, Human / Q000235:genetics; D006801:Humans; D017403:In Situ Hybridization / Q000379:methods; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000821:virology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D012367:RNA, Viral / Q000032:analysis; D014412:Tumor Virus Infections / Q000473:pathology / Q000821:virology
chemical_list: D004279:DNA, Viral; D019253:Proto-Oncogene Proteins c-bcl-2; D012367:RNA, Viral