Age-Specific Characteristics and Malignancy Risk of Ovarian Teratomas: A Retrospective Single-Centre Study

<b>Aim:</b> The aim of this study was to determine the age-specific characteristics of ovarian teratoma and associated malignancies. <b>Methods:</b> This retrospective single-centre cohort study included 2181 women with ovarian teratoma who underwent surgery at our institution between January 2008 and April 2019. Malignancies associated with ovarian teratoma were divided into immature teratoma, combined ovarian malignancy, and malignant transformation of mature cystic teratoma. The median patient age was 30 years (range, 7-82) and the median follow-up duration was 10 months (range, 0-152). <b>Results:</b> Most ovarian teratomas were detected incidentally, except in patients with abdominal pain under 20 years of age; torsion was significantly more common in this age group (<i>p</i> < 0.001). Tumours were larger in the younger age group (<i>p</i> < 0.01). The incidence of immature teratoma was 0.5% (<i>n</i> = 11), that of combined ovarian malignancy was 0.4% (<i>n</i> = 9), and that of malignant transformation was 0.4% (<i>n</i> = 9). The median patient age was 24.0 years for immature teratoma and 27.0 years for combined ovarian malignancy. The most common cell type was mucinous borderline tumour (55.6%, <i>n</i> = 5). The median patient age of malignant transformation was 33.0 years, and the most common cell type was carcinoid tumour (77.8%, <i>n</i> = 7). At our institution, the clinical manifestations of ovarian teratoma varied according to age group, with younger patients being more likely to be symptomatic and to have larger tumours and bilateral tumours. Although there was no statistically significant relationship between age and associated malignancy (<i>p</i> = 0.442), most of the malignancies associated with ovarian teratoma were found in childbearing age, not in older age. <b>Conclusions:</b> Given the possible associated malignancy with ovarian teratoma, surgeons should perform detailed preoperative evaluations, avoid intraoperative spillage, and perform intraoperative frozen biopsy when appropriate.