Not all teratomas require immediate surgery. If a teratoma is found to be relatively small in size, many people can have it remain stable for a long time without significant changes, therefore periodic monitoring is possible. However, if a teratoma shows a rapid increase in size, or if it is already very large with the potential for torsion, or if there is a possibility of rupture or malignant transformation, or if the teratoma has endocrine activity, then immediate surgery may be necessary.