Differential Diagnosis
Endometrioid ovarian cancer may arise from an atypical endometrioma. Distinguishing these two pathologies on imaging may sometimes be challenging due to a number of factors: the ovarian parenchyma adjacent to an endometriotic cyst can be mistaken for an enhancing solid malignant nodule, deep invasive endometriosis of the recto-sigmoid colon can mimic the “mushroom cap” sign associated with invasive malignancy (30)