We retrospectively reviewed all pediatric patients (aged ≤15 years at diagnosis) with OGCTs treated between January 2016 and January 2021 at Children’s Hospital No.2 in Ho Chi Minh City, Vietnam. We recorded their symptoms, age at diagnosis, imaging, tumor markers, treatment methods, and complications.

The OGCT diagnosis was based on a combination of clinical presentation, tumor markers (alpha-fetoprotein [AFP] and beta human chorionic gonadotrophin [βhCG]), and imaging characteristics. In cases where preoperative and intraoperative features suggested a benign tumor and its macroscopic appearance allowed for separating the ovarian tissue from the tumor, an ovarian tissue-sparing tumorectomy was performed. However, if there was any uncertainty about the benign nature of the tumor before surgery, a complete unilateral spingo-oophorectomy was performed. In situations where complete tumor resection risked injury to adjacent organs, resection was canceled, and neoadjuvant chemotherapy was administered. In such cases, a second surgery was performed to remove residual tumors and/or lymph nodes. Our study used the Children’s Oncology Group (COG) staging system. Immature teratomas were graded according to the Norris classification. The median follow-up was 3.3 years (3 months to 6.5 years).

This study was approved by the ethics committee of Children’s Hospital No.2 (225/QĐ-BVNĐ2) and accepted by The University of Medicine and Pharmacy at Ho Chi Minh City6.

All statistical analyses were performed using SPSS software (version 25.0; IBM, United States). Discrete variables are described as percentages. Continuous variables are described as means and standard deviations when normally distributed or medians with ranges when non-normally distributed. Normally distributed continuous variables were compared between groups using Student’s t-test, and non-normally distributed continuous variables were compared using the nonparametric Mann–Whitney U test. Discrete variables were compared between groups using Fisher’s exact test. A 95% confidence interval was used, and a p < 0.05 was considered statistically significant.

Overall survival (OS) was calculated as the time from the date of diagnosis to death from any cause. Event-free survival (EFS) was calculated as the time between diagnosis and any event (e.g., malignant germ cell recurrence and death). The last follow-up was censored for patients who remained alive. Survival was analyzed using the Kaplan–Meier method.

Our study enrolled all 162 patients with a mean age of 9.1 ± 3.6 years (1–15 years). At admission, their most common complaint was abdominal pain (73.5%), followed by abdominal mass (20.4%). Among them, 23 (13%) were discovered incidentally with ultrasound. No patient with mature teratomas had elevated AFP or βhCG levels. However, AFP levels were elevated in 19 (11.7%) patients (47–105,031 ng/mL): nine with immature teratomas, seven with yolk sac tumors, one with dysgerminoma, and two with malignant mixed germ cell tumors. Four (2.5%) patients had elevated βhCG levels (60–16,638 mIU/mL): two with dysgerminomas and two with malignant mixed germ cell tumors (Table 1).

Cell surface-associated mucin 16 (MUC16/CA-125) levels were measured at diagnosis in 68 patients. They were elevated in 17 patients: seven with mature teratomas, five with immature teratomas, four with yolk sac tumors, and one with dysgerminoma.

Table 1

Parameters	Number (%)
Mean (range)	9.1 (1-15 years)
Presenting symptoms
Abdominal pain	119 (73.5%)
Abdominal mass	33 (20.4%)
Vomitting	21 (13.0%)
Valginal bleeding	5 (3.1%)
Urinary symptoms	1 (0.6%)
Constipation	1 (0.6%)
Prepubertal	105 (64.8%)
Postpubertal	57 (35.2%)
Presenting signs
Palpable mass	119 (73.5%)
Tumor markers
Elevated
AFP	19 (11.7%)
hCG	4 (2.5%)
AFP and bhCG	3 (1.9%)
Normal	142 (87.7%)
Imaging
US	162 (100%)
CT	108 (66.7%)

Table 2

Histopathology	n (%)
Mature teratoma	137 (84.6%)
Immature teratoma	11 (6.8%)
Grade 1	6
Grade 2	1
Grade 3	4
Yolk sac	7 (4.3%)
Dysgerminoma	5 (3.1%)
Mixed germ cell	2 (1.2%)
Total	162

Table 3

Surgical procedure	n (%)	Malignant No.
Collection of ascites	24 (96%)	2 (8.3%)
Omentectomy	22 (88%)	8 (36.4%)
Lymph node sampling	17 (68%)	4 (23.5%)
Peritoneal biopsied	8 (32%)	4 (50%)
Contralateral ovarian biopsy	2 (8%)	0
Total	25

Figure 2

Figure 3

Figure 4

The tumor structure was reported to be cystic in 62 (38.3%) patients, solid in 18 (11.1%), and mixed cystic-solid in 82 (50.6%).

The median tumor size was 7.8 cm (2.8–32.0 cm). All malignant tumors exceeded 6 cm, with an average of 12 cm (6.5–25.0 cm), significantly larger than mature teratomas (mean = 7.3 cm, range = 2.8–32.0 cm, p < 0.001). We examined two different diameter thresholds to determine which would be the most helpful clinically: 6 cm (the size that all malignancies exceeded in our study) and 8 cm7. A threshold of ≥ 8 cm had a sensitivity of 84% and a specificity of 62.8% for malignant tumors. A threshold of ≥ 6 cm had a sensitivity of 100% and a specificity of 42% for malignant tumors.

Calcifications were observed in 108 (66.7%) patients. Fat nodes were observed in 91.7% of patients with teratomas and 25% with malignant OGCTs.

The predominant histopathologic subtype was mature teratoma (n = 137, 84.5%), followed by immature teratomas (n = 11, 6.8%) and malignant tumors (n = 14, 8.6%; Table 2).

Immature teratomas and malignant tumors were staged postoperatively. Seven patients had stage I, five had stage II, 17 had stage III, and none had metastasis at diagnosis.

The tumors were right-sided in 90 (55.6%) patients, left-sided in 64 (39.5%), and bilateral in eight (4.9%). At operation, 35 (21.6%) patients had ovarian torsion: 33 with mature teratomas and two with malignant tumors. Seven patients experienced preoperative tumor rupture, and 11 experienced intraoperative rupture. Ruptures were more common with laparoscopy (13.2%) than laparotomy (2.3%, p = 0.011). The mean operating time was 83.8 ± 27.3 min. Operating time did not differ significantly between laparoscopy (76.5 ± 21.3 min) and laparotomy (83.1 ± 20.3 min) for mature teratomas (p = 0.067).