[606] Algorithm for Diagnosis of Gastrointestinal Stromal Tumor Using Immunohistochemstry of C-Kit and PDGFRA with Molecular Analysis

JS Kim, HI Bae, JH Kim, HJ Oh, HY Kim, IS Suh, JG Kim. Kyungpook National University Hospital, Daegu, Korea

Background: Gastrointestinal stromal tumor(GIST) is relatively rare disease, but the most common sarcoma in gastrointestinal tract. Immunoreactivity for c-kit helps to diagnose GIST with histologic features, positive vimentin and CD34 staining. Recently, many kinds of methods for the diagnosis of GIST have been developed including molecular diagnosis.
Design: Available 90 cases of GIST were selected in Department of Pathologoy of Kyungpook National University Hospital(KNUH) during 19982007. Tissue microarray(TMA) were made using core area of tumor tissues, which are representatives of the most cellular area. IHCs for c-kit and PDGFRA were done. And direct sequencing of hot spot exonal areas for c-kit and PDGFRA were performed from extracted DNAs of all 90 paraffin block tissue.
Results: Among 90 cases, 83.3%(75/90) were c-kit positive, 16.6%(15/90) were c-kit negative. And 93.3%(84/90) were PDGFRA positive, 6.6%(6/90) cases were PDGFRA negative. 15 cases of c-kit negative GISTs contained 1 case of PDGFRA negative, and 5 cases of PDGFRA negative GISTs showed c-kit positive. The 1 case, both c-kit and PDGFRA negative showed c-kit mutation in exon 11.
Conclusions: Combined with c-kit, immunohistochemical staining of PDGFRA is helpful for diagnosis of GIST. When both staining show negative immunoreactivity, c-kit mutation analysis for exon 11, 9 should be done first. And then PDGFRA mutation analysis for exon 12, 18 is recommended next. All GISTs are not need to examine mutational analysis first.
Category: Gastrointestinal

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 89, Wednesday Morning