ABSTRAK
Latar belakang: Sarkoma Ewing merupakan suatu small round cell tumor yang ditandai dengan fusi gen EWSR1/FLI1 pada 85 kasus. Diagnosis akurat diperlukan karena memiliki respon baik terhadap protokol kemoterapi spesifik. Baku emas diagnosis sarkoma Ewing adalah deteksi translokasi spesifik dengan RT-PCR atau FISH, namun pemeriksaan tersebut belum tersedia di institusi kami, sehingga dilakukan upaya lain untuk mempertajam diagnosis. Secara morfologi, sarkoma Ewing sering overlapping dengan small round cell tumor lainnya. Pulasan CD99 merupakan penanda yang sangat sensitif untuk mendiagnosis sarkoma Ewing, namun juga sering overlapping dengan small round cell tumor lainnya. Beberapa penelitian mengemukakan FLI1 dapat digunakan sebagai penanda diagnosis sarkoma Ewing. Tujuan penelitian ini adalah menilai ekspresi FLI1 untuk membantu menegakkan diagnosis sarkoma Ewing pada small round cell tumor yang memberikan hasil positif terhadap CD99, terutama pada kasus biopsi.Bahan dan cara: Penelitian ini menggunakan desain potong lintang. Sampel terdiri atas 36 kasus sarkoma Ewing dan 18 kasus small round cell tumor yang sudah dilakukan pulasan imunohistokimia CD99 di RSCM dari Januari 2011 sampai Mei 2018. Dilakukan pulasan FLI1 dan penilaian menggunakan H-score.Hasil: Titik potong H-score pada ekspresi FLI1 didapatkan 226.1 75 dengan sensitivitas 81.6 dan spesifisitas 94.4 . Ekspresi FLI1 tinggi didapatkan pada 31 kasus sarkoma Ewing, sedangkan pada 18 kasus small round cell tumor umumnya memiliki ekspresi FLI1 yang rendah ABSTRACT
Background: Ewing 39;s sarcoma is a small round cell tumor characterized by EWSR1 / FLI1 gene fusion in 85 of cases. Accurate diagnosis is necessary because it has a good response to a specific chemotherapy protocol. The gold standard of Ewing 39;s sarcoma diagnosis is the detection of specific translocation with RT-PCR or FISH, but the examination is not yet available at our institution, so another attempt is made to sharpen the diagnosis. Morphologically, Ewing 39;s sarcoma is often overlapping with other small round cell tumor. CD99 is a very sensitive marker for diagnosing Ewing 39;s sarcoma, but also often overlapping with other small round cell tumors. Several studies have suggested that FLI1 can be used as a marker of Ewing rsquo;s sarcoma. The purpose of this study was to assess the FLI1 expression to help establish the diagnosis of Ewing rsquo;s sarcoma in small round cell tumors that gave CD99 positive results, especially in the biopsy cases. Materials and methods: This was a cross-sectional study with 36 cases of Ewing rsquo;s sarcoma and 18 cases of other small round cell tumor that had been performed CD99 immunohistochemistry at RSCM from January 2011 to May 2018. All cases stained by FLI1 antibody and evaluated using H-score. Results: The H-score cut-off point on FLI1 expression was obtained at 226.1 75 with 81.6 sensitivity and 94.4 specificity. The high FLI1 expression was obtained in 31 cases of Ewing rsquo;s sarcoma, while in 18 cases of small round cell tumor were generally had low expression of FLI1 p