Clinical history: 55 year old female with unilateral 40 cm cystic ovarian mass.
What is the diagnosis?
Ovarian Borderline Mucinous Tumor (OBMT)
You are seeing the wall of one of the cysts in the ovary. It is lined by both endocervical and intestinal type mucinous cells. In the intestinal type epithelium areas the cells are becoming stratified with increased epithelial proliferation. The nuclei do not show pronounced cytologic atypia. These changes, if present in more than 10% of the sections, meet the criteria for an ovarian borderline mucinous tumor. There is no evidence of invasion.
Things you should be able to rhyme off on an exam include:
Borderline ovarian tumors (mucinous, serous, endometroid, etc) comprise up to 15-20% of ovarian epithelial neoplasm
These tumors are histologically characterized by a stratified growth pattern, but without stromal invasion.
OBMT most often present as large (up to 50 cm) unilateral multiloculated mass
OBMT are most common in perimenopausal women (45 years)
OBMT most often have intestinal type epithelium (90%)
If you have a pure intestinal type borderline mucinous tumor you should always rule out an appendiceal origin, especially if there is bilateral disease or if the patient has pseudomyxoma peritonei
10% of OBMT have endocervical type epithelium, these are often bilateral (40%) and are often associated with acute inflammation or endometriosis
Up to 60% have KRAS mutations
5 year survival is >95%
These tumors should be extensively sampled to rule out areas of invasion (1-2 sections/cm)