title: C-Kit (CD117) expression in AIDS-related, classic, and African endemic Kaposi sarcoma.
abstract: Kaposi sarcoma (KS) is a multicentric vascular neoplasm characterized histologically by the progressive proliferation of spindle-shaped tumor cells in all epidemiologic (AIDS-related, classic, endemic, and iatrogenic) forms. Human herpesvirus 8 (HHV8) is associated with all epidemiologic forms of KS and has been shown in vitro to induce the tyrosine receptor kinase c-kit in HHV8-infected cells. To date, c-kit immunoreactivity has not been systematically studied in KS lesions. Therefore, the aim of this study was to evaluate c-kit expression by immunohistochemistry in different proliferative stages and epidemiologic forms of KS. Archival cases of formalin-fixed, paraffin-embedded KS lesions, including 9 classic, 11 AIDS-related, and 15 African (endemic) forms at various histologic stages (5 patch, 8 plaque, 22 nodular), biopsied from different sites, were stained using immunohistochemistry with antibodies to HHV8 (LNA-1) and c-kit (CD117). C-kit immunoreactivity of lesional cells was demonstrated in 15 (43%) cases overall. A total of five (56%) classic, five (45%) AIDS-related, and five (33%) endemic KS cases were positive for c-kit. There was no difference in the intensity of c-kit staining between the different epidemiologic groups and histologic stages of KS. HHV8 (LNA-1) immunoreactivity was present in all (100%) classic, 10 (91%) AIDS-related, and 9 (60%) endemic cases. LNA-1 staining was demonstrated in 13 (93%) of the c-kit-positive and 15 (75%) of the c-kit-negative KS lesions. These findings indicate that c-kit expression in lesional cells can be detected by immunohistochemistry in different epidemiologic forms and histologic stages of KS. Furthermore, the expression of c-kit does not correspond with the presence of HHV8 (LNA-1) immunoreactivity in KS lesions.
authors.affiliation: Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA. lpantanowitz@hotmail.com
authors.forename: Liron
authors.initials: L
authors.lastname: Pantanowitz
authors.forename: Erich J
authors.initials: EJ
authors.lastname: Schwartz
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Dezube
authors.forename: Sabine
authors.initials: S
authors.lastname: Kohler
authors.forename: Ronald F
authors.initials: RF
authors.lastname: Dorfman
authors.forename: Steven R
authors.initials: SR
authors.lastname: Tahan
mesh_terms: D000328:Adult; D006678:HIV / Q000276:immunology; D015658:HIV Infections / Q000150:complications / Q000276:immunology* / Q000473:pathology; D019288:Herpesvirus 8, Human / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000276:immunology; D010750:Phosphoproteins / Q000276:immunology; D019009:Proto-Oncogene Proteins c-kit / Q000276:immunology*; D012514:Sarcoma, Kaposi / Q000276:immunology* / Q000473:pathology
chemical_list: D009687:Nuclear Proteins; D010750:Phosphoproteins; C118485:latent nuclear antigen (LNA); D019009:Proto-Oncogene Proteins c-kit