Clinical history: 46 year-old female with unilateral complex cystic mass in the left ovary measuring 27.0cm in maximum dimension.
What is the most probable diagnosis?
Metastatic adenocarcinoma diagnosis is most common, but this is invasive ovarian mucinous carcinoma, expansive 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 you always have 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. The expansive invasive carcinoma is defined by >5mm of confluent highly atypical glands with minimal invasive into the stroma.
Expansive invasive carcinomas which behave in a “benign” fashion