Ovarian teratomas are a relatively common type of ovarian tumor and belong to germ cell tumors. Depending on the benign or malignant nature of the teratoma, their differentiation and growth rates vary, meaning they grow at different speeds. For instance, benign teratomas, also known as mature teratomas, usually grow slowly. Many women may find that, upon having a check-up every six months or a year, the size of the teratoma remains the same with no significant changes. However, some women may have malignant teratomas, or their previously mature teratomas may become malignant. In such cases, the mass may suddenly increase in size over a short period, causing abdominal pain, and sometimes the mass can be felt in the abdomen.