Borderline Ovarian Tumours
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Direct answer
Borderline ovarian tumours — tumours of low malignant potential — are epithelial neoplasms with cellular atypia and epithelial proliferation but no destructive stromal invasion, arising in women roughly two decades younger than ovarian carcinoma and carrying an excellent prognosis, with five-year survival for stage I disease above 90%. Serous borderline tumours account for about two-thirds — bilateral in roughly a third, exophytic and papillary, often with psammoma bodies and a raised CA-125 — while mucinous borderline tumours are large, unilateral, multilocular masses. Management is surgical, and in young women fertility-sparing surgery with unilateral adnexectomy is standard; the pathology that decides outcome is the peritoneal implant: non-invasive implants behave indolently and receive no chemotherapy, while invasive implants mark disease that behaves like low-grade serous carcinoma. Recurrences are characteristically late, sometimes a decade on, so surveillance continues for years after the diagnosis.
What you must remember
- Definition: epithelial proliferation with atypia and stratification but no destructive stromal invasion; stromal microinvasion of tiny foci does not by itself change management.
- The micropapillary or cribriform serous variant is the aggressive subtype — strongly associated with invasive implants and higher recurrence, and now grouped by WHO terminology close to low-grade serous carcinoma.
- Peritoneal implants decide prognosis: non-invasive implants are managed by surgery and surveillance, invasive implants behave as low-grade serous carcinoma and are the strongest adverse factor.
- Every mucinous ovarian tumour prompts appendicectomy or at least thorough appendiceal examination — an appendiceal primary can masquerade as an ovarian mucinous tumour, and pseudomyxoma peritonei is usually appendiceal in origin.
- Frozen section is unreliable, undercalling carcinoma especially in large and mucinous tumours — plan the operation accepting that final paraffin pathology may upgrade the diagnosis and mandate restaging.
- Fertility-sparing surgery: unilateral salpingo-oophorectomy with staging biopsies for young women with stage I disease; cystectomy alone risks substantially higher recurrence and is reserved for exceptional circumstances; completion surgery is commonly advised after childbearing.
- No adjuvant chemotherapy for borderline histology with non-invasive implants — there is no demonstrated benefit; invasive implants may justify platinum-based treatment as for low-grade serous carcinoma, though sensitivity is limited.
- Nodal involvement can occur without the dire meaning it carries in carcinoma; surveillance — clinical review, ultrasound and CA-125 in serous disease — continues five to ten years because recurrence is late.
From frozen section to final plan
A 32-year-old undergoes surgery for an 8 cm multilocular right ovarian cyst; frozen section reports a mucinous borderline tumour. The steps that follow are worth narrating: peritoneal washings, careful inspection of both ovaries, the pelvis and the entire peritoneum with biopsies of anything suspicious, appendicectomy because the appendix is the hidden primary in mucinous disease, and right salpingo-oophorectomy preserving uterus and left ovary — avoiding capsular rupture. Final paraffin sections confirm borderline histology with a normal appendix and no implants: stage I, no adjuvant therapy, annual surveillance with ultrasound. Had the final pathology upgraded the tumour to carcinoma, the conversation becomes one of formal staging or completion surgery. Should she represent seven years later with a rising CA-125 and a pelvic mass — the classic late recurrence — the pathway is imaging and secondary cytoreductive surgery, not reflex chemotherapy.
Where students slip
The first error is prescribing chemotherapy for stage I borderline disease with non-invasive implants — this is a surgical disease, and chemotherapy adds toxicity without benefit. The second is treating the frozen section as gospel; undercalling is common and the operation must be planned around final histology. The third is forgetting the appendix in mucinous tumours, and the fourth is discharging patients at five years when recurrences characteristically arrive later. The fifth is shrugging off the micropapillary pattern as a detail — it correlates with invasive implants and demands closer surveillance and more explicit consent about recurrence risk.
Frequently asked questions
What defines a borderline ovarian tumour?
Epithelial proliferation with atypia and stratification but no destructive stromal invasion — histologically between benign cystadenoma and carcinoma.
How do invasive and non-invasive implants differ?
Non-invasive implants sit on peritoneal surfaces and behave indolently; invasive implants infiltrate tissue, behave like low-grade serous carcinoma and drive prognosis and treatment intensity.
What fertility-sparing options exist?
Unilateral salpingo-oophorectomy with staging in young women with stage I disease; cystectomy only in exceptional cases because recurrence is substantially higher, with completion surgery advised after childbearing.
Is there a role for chemotherapy in borderline tumours?
Not for disease with non-invasive implants; invasive implants may justify platinum-based treatment as for low-grade serous carcinoma, acknowledging limited chemosensitivity.
Why is the appendix examined in mucinous borderline tumours?
Because appendiceal neoplasms can produce identical ovarian deposits and pseudomyxoma peritonei is usually appendiceal in origin — appendicectomy removes the masquerade.
How long should surveillance continue?
At least five to ten years with clinical review, ultrasound and CA-125 where serous, because recurrences are characteristically late.