A Case of Bilateral Decidualized Endometriomas during Pregnancy: Radiologic-pathologic Correlation.

Clinical differentiation between decidualized endometrioma and malignant transformation still poses difficulties as both are intracystic vascularized excrescences of an endometrial cyst and exhibit similar characteristics on color-flow Doppler sonography. This is a characteristic sonographic finding associated with ovarian cancer, but MRI can provide further information about mural excrescences that can aid in their differential diagnosis; for example, the signal of decidualized endometriomas is isointense with the placenta within the uterus on all sequences and the apparent diffusion coefficient is higher than that of malignant mural nodules. Thus, MRI should be an aid in deciding whether to intervene during pregnancy. However, considering that it is not yet possible to clearly differentiate decidualized endometriomas from ovarian cancer, surgery or watchful observation may still be needed to exclude the possibility of malignancy.