The archival materials are 43 cases of ovarian surface epithelial tumors, which are 39 patients collected from the files Pathology Department of Kyungpook National University Hospital and 4 cases from Daegu Fatima hospital from 2000 to 2004. The 43 patients are consisted of 26 cases of carcinomas, 7 cases of borderline tumors, and 10 cases of benign tumors. All the patients with carcinomas and borderline tumors underwent abdominal hysterectomy with unilateral or bilateral salpingo-oophorectomy. The hematoxylin-eosin stained slides were reviewed and one block per case representative for the tumor was selected for immunohistochemistry and mutational analysis. The clinical informations was based on the patient's medical records.

Five µm of formalin-fixed paraffin-embedded tissue sections were cut and immunostained with polyclonal rabbit antibody c-kit (A4502, Dako, Carpinteria, CA, U.S.A.). Each section was deparaffinized using xylene and subsequent hydration. The immunohistochemical studies were performed using the streptavidine-biotin-peroxidase (Ultra Vision Kit; LAB vision, Fremont, CA, U.S.A.) with diaminobenzidine (DAB) as chromogen and Mayers' hematoxylin as nuclear counterstain. The assays were performed on an automated stainer (BenchMark model; Ventana, Tucson, AZ, U.S.A.). Sections of GIST were used as positive control. The intensity of the immunostaining was graded as negative (no staining), 1+ (weak), 2+ (moderate), or 3+ (strong). Tumors staining in greater than 10% of the tumor cells were considered to be positive.

From formalin-fixed paraffin-embedded tissue samples, we cut 10-µm thick sections from each sample. Genomic DNA was extracted using QIAamp DNA mini kit (Qiagen, Germany). Exons 11 and 17 of c-kit gene were amplified by PCR using primers described in Table 1. Each PCR reaction was performed in 20 µL of reaction volume: 200 ng of genomic DNA, commercial Perkin-Elmer (PE) buffer (1×10 mM Tris-HCl, pH 8.4; 50 mM KCl), 1.5 mM MgCl₂, 200 µM of each triphosphodeoxy-nucleotides (dNTP), one unit of AmpliTaq Gold (PE) polymerase, and 0.1 µM of each primers. In the case of exon 11, the reaction mixture was denatured at 94℃ for 3 min and subjected to 40 polymerization cycles (94℃ for 30 sec, 51℃ for 30 sec, and 72℃ for 60 sec). In the case of exon 17, the reaction mixture was denatured at 94℃ for 5 min and subjected to 40 polymerization cycles (94℃ for 30 sec, 51℃ for 30 sec, and 72℃ for 30 sec). PCR reaction was run in GeneAmp 9600 thermocycler (PE).

PCR-SSCP analysis for exon 11 and 17 were performed in all cases. For SSCP analysis, each PCR product was mixed with an equal volume of loading buffer (95% formamide, 0.05% bromophenol blue, and 0.05% xylene cyanol). After denaturation at 94℃ for 5 min and snap cooling on ice, 3 µL of each sample was loaded on polyacrylamide gels and subjected to electrophoresis. For the analysis of exon 11, 10% polyacrylamide gel was used and 8% gel was used for exon 17. The gels were stained using Silver Stain Plus kit (Bio-Rad, Hercules, CA, U.S.A.), according to the manufacturer's recommendation.

The 33 cases included 13 serous cystadenocarcinomas, 1 borderline serous tumor, 8 mucinous cystadenocarcinomas, 6 borderline mucinous tumors and 5 clear cell carcinomas. To compare with the benign counterparts, 5 cases of serous cystadenoma and 5 cases of mucinous cystadenoma were included in the study. The mean age was 43.3 yr (range 20 to 76 yr). The stages of the carcinomas were as follows: Stage I 11 cases, Stage II 3 cases, Stage III 12 cases. All the patients with carcinomas and borderline tumors underwent total hysterectomy with unilateral or bilateral salpingo-oophorectomy. The serous cystadenocarcinoma patients underwent omentectomy and appendectomy with careful examination of all serosal surfaces and biopsies of any suspected lesions. Ten cases of serous cystadenocarciomas had omental or pelvic metastasis of tumor cells. After surgery, a postoperative chemotherapy was performed in mucinous and serous cystadenocarcinoma, and clear cell carcinoma patients except two patients. One patient was stage Ia mucinous cystadenocarcinoma and the other was stage Ia clear cell carcinoma. The chemotherapy cycles were 6 to 12 cycles, consisted of cisplatin, cyclophosphamide and taxol. Two patients of serous cystadenocarcinoma and one patient of clear cell carcinoma recurred, but all patients are still alive.

Three cases (3/6, 50%) of borderline mucinous cystic tumors and two cases (2/8, 25%) of mucinous cystadenocarcinomas showed positive cytoplasmic staining for KIT protein (Fig. 1). Only one case (1/13, 7.7%) of serous cystadenocarcinoma had positive staining (Fig. 2). The intensity was focal weak or moderate. None (0/5) of clear cell carcinomas showed positive staining. The benign mucinous and serous cystadenomas were all negative.

Mutational analysis was applied to all cases of carcinomas and borderline tumors. No mutation was identified at exon 11. Two cases of borderline mucinous tumors and one case of mucinous cystadenocarcinoma had mutation at exon 17 (Fig. 3, 4). In these cases, the immunohistochemistry also shows focal positive staining at epithelial component. The results are presented in Table 2.

In immunohistochemical results, two cases of c-kit positive mucinous cystadenocarcinoma were stage Ic and II. One case of serous cystadenocarcioma was stage IIIc with pelvic metastasis but no recurrence. In exon 17 mutational analyses, one patient with mucinous cystadenocarcinoma had stage Ic.