Decidualized endometrioma mimicking malignancy: A case report and literature review of magnetic resonance imaging findings

Decidualized endometrioma is a special type of endometrioma caused by progesterone stimulation during pregnancy. Hypertrophied endometrial tissues present as solid components that can mimic malignancy. Characteristic imaging features can differentiate between a decidualized endometrioma and a malignancy. We report a case of a 33-year-old pregnant woman who presented with an ovarian cystic lesion with mural nodules. The magnetic resonance imaging findings, such as T1 hyperintensity and T2 shading of the cystic component, T2 hyperintensity, low height, and the high apparent diffusion coefficient of mural nodules, provide key information for diagnosing decidualized endometrioma and can help patients avoid unnecessary surgery.