Clinical history: 47 year-old female with unilateral complex cystic mass in the left ovary measuring 17.0cm in maximum dimension.
What is the most probable diagnosis?
Metastatic adenocarcinoma diagnosis is most common, but this is invasive ovarian mucinous carcinoma, infiltrative pattern
Ovary mucinous tumours are the second most frequent epithelial tumor after serous representing ~15% of ovarian neoplasms. They usually present in middle aged adults, pre-menopausal. 80% are benign, 10% are borderline and 10% are carcinoma. The majority (77%) of ovarian mucinous carcinomas are metastases, so it is important to rule these out.
Grossly they are usually unilateral, very cystic and present as very large masses (>10cm). They usually have a smooth outer surface with variable solid areas and are filled with sticky, gelatinous fluid rich in glycoproteins
Histologically the mucin producing cells can resemble endocervical, gastric, or intestinal type epithelium.
Invasive carcinomas are usually of the intestinal type and can be classified as expansive or infiltrative.
Infiltrative pattern is defined as small clusters of cells and/or single cells infiltrating into the stroma in contiguous area greater than >5mm. Infiltrative invasive carcinomas have a worse prognosis than expansive invasive carcinomas which behave in a “benign” fashion.