Ovarian Clear Cell Carcinoma Arising in a Large Endometrioma — A Case Report with Pathological Correlation and Literature Review

Endometriosis-associated ovarian cancer represents the most common form of malignancy associated with this benign disease. It has a better prognosis than most types of ovarian cancer, with endometrioid adenocarcinoma and clear cell carcinoma as the main histological types. Clinical presentation is usually nonspecific and tumor biomarkers can be misleading, since they can also be elevated in the presence of benign ovarian endometriosis. We report a case of a 52-year-old woman with known ovarian and deep pelvic endometriosis, who developed ovarian clear cell carcinoma within a large endometrioma. The imaging findings highlight the key role of magnetic resonance imaging in detecting suspicious features such as loss of the “T2 shading” sign, loss of high T1 signal of an endometrioma, or the presence of mural nodules. Early detection of these malignancies is fundamental for adequate surgical treatment and overall outcome.