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Ovarian cancer

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Tumours of borderline malignancy

Tumours of borderline malignancy are epithelial tumours that don’t clearly appear to be cancerous. They account for approximately 15% of all epithelial ovarian tumours. They may occur in one or both ovaries.

These tumours are also known as:

  • tumours or ovarian cancer of low malignant potential (LMP)
  • borderline tumours
  • atypical proliferative tumours
  • borderline epithelial ovarian cancer

Tumours of borderline malignancy are different from typical ovarian cancers.

  • Although the cells of the tumour appear malignant (cancerous), they have not invaded the underlying or nearby tissue.
  • If they spread outside the ovary into the abdominal cavity, they may grow on the lining of the abdomen, but they don’t grow into it.
  • The tumours grow slowly and most are stage I at diagnosis.
  • The tumours tend to develop in women at a younger age than most ovarian cancers.

Types of tumours include:

  • serous tumours
  • mucinous tumours (gastrointestinal type or endocervical-like type)
  • endometrioid tumours
  • clear cell tumours
  • transitional cell tumours (Brenner tumour) – usually benign


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