Benign Ovarian Tumours

Ovarian tumours can be divided into three main groups, functional, benign and malignant. Any of the ovary's many tissue types may become neoplastic. In relative frequency, functional cysts account for about 24% of all ovarian cysts, benign cysts 70% and malignant 6% (see separate article on Ovarian Cancer). There is a separate article on Ovarian Tumours and Fibroids in Pregnancy.

Benign ovarian tumours are usually slow growing and rarely become malignant. The most common benign ovarian tumours are benign cystic teratomas (also called dermoid cysts because they consist mainly of ectodermal tissue). Fibromas are the most common solid benign ovarian tumours.

Benign neoplastic cysts

• Serous cystadenoma:
  • Develop papillary growths which may be so prolific that the cyst appears solid.
  • They are commonest in women aged between 30 and 40 years.
  • About 30% are bilateral and about 30% are malignant.
• Mucinous cystadenoma:
  • Commonest large ovarian tumours and may become enormous.
  • They are filled with mucinous material and rupture may cause pseudomyxoma peritonei. They may be multilocular.
  • They are commonest in the 30-50 age group. About 5% will be malignant.

Benign neoplastic cystic tumours of germ cell origin

• Benign cystic teratoma; rarely malignant
• Arise from primitive germ cells
• A benign mature teratoma (dermoid cyst) may contain well differentiated tissue e.g. hair, teeth.
• 20% are bilateral
• They are most common in young women
• Poorly differentiated, malignant teratomas are rare

Benign neoplastic solid tumours

• Fibroma (fewer than 1% are malignant); small, solid benign fibrous tissue tumours. They are associated with Meigs' syndrome and ascites
• Thecoma (fewer than 1% are malignant)
• Adenofibroma
• Brenner tumour:
  • Rare ovarian tumours displaying benign, borderline or proliferative, and malignant variants
  • Over 95% are benign and more than 90% are unilateral
  • May be associated with mucinous cystadenoma and cystic teratoma

• Benign ovarian tumours occur in 30% of females with regular menses and 50% of females with irregular menses.
• Predominantly occur in premenopausal women; may also occur perinatally.
• Benign ovarian tumours are uncommon in premenarchal and postmenopausal women and should then raise suspicion of malignancy.
• Benign neoplastic cystic tumours of germ cell origin are most common in young women. They account for 15-20% of all ovarian neoplasms.

Risk factors

• Obesity
• Tamoxifen therapy has been associated with an increase in persistent ovarian cysts
• Early menarche
• Infertility
• Hypothyroidism

• Asymptomatic; chance finding (e.g. on bimanual examination or ultrasound)
• Dull ache or pain in the lower abdomen, low back pain
• Torsion or rupture may lead to severe abdominal pain and fever
• Dyspareunia
• Swollen abdomen; with palpable mass arising out of the pelvis which is dull to percussion and does not disappear if the bladder is emptied
• Pressure effects; e.g. on the bladder, causing urinary frequency, or on venous return causing varicose veins and leg oedema
• Torsion, infarction or haemorrhage:
  • Cause severe pain
  • Torsion may be intermittent, presenting with intermittent episodes of severe pain
• Rupture:
  • Rupture of a large cyst may cause peritonitis and shock
  • Rupture of mucinous cystadenomas may disseminate cells which continue to secrete mucin and cause death by binding up the viscera (pseudomyxoma peritonei)
• Ascites; suggests malignancy or Meigs' syndrome
• Endocrine; hormone-secreting tumours may cause virilisation, menstrual irregularities or post-menopausal bleeding

• Non-neoplastic functional cysts e.g. follicle cyst, corpus luteum cyst, theca lutein cyst
• Any other cause of pelvic pain
• Polycystic ovary syndrome
• Endometrioma
• Ovarian malignant tumour
• Bowel; colonic tumour, appendicitis/appendix mass, diverticulitis
• Gynaecological; pelvic inflammatory disease, tubo-ovarian abscess, uterine tumour (e.g. fibroid), ectopic pregnancy, parovarian cyst
• Pelvic malignancies e.g. retroperitoneal tumours, small intestine tumours and mesothelial tumours

• Pregnancy test (uterine or ectopic pregnancy)
• Full blood count; infection, haemorrhage
• Urinalysis; if urinary symptoms
• Ultrasound; transvaginal and abdominal
• CT scan; usually required only if ultrasound results are not definitive or if intra-abdominal processes are suspected
• Diagnostic laparoscopy; for unilocular non-solid tumours less than 7cm in size; visualisation with excision of the pathology
• Laparotomy; if malignancy cannot be ruled out before the procedure
• Fine needle aspiration and cytology may be used to confirm the impression that a cyst is benign
• Cancer antigen-125 (CA-125):
  • Elevated in over 90% of patients with advanced ovarian carcinoma and in 50% of patients with early stage ovarian disease
  • CA-125 is of value in the differential diagnosis of benign and malignant ovarian masses
  • For women with a pelvic mass, CA-125, in addition to pelvic examination and pelvic ultrasound, improves the sensitivity and specificity for ovarian cancer, especially in postmenopausal women¹
  • CA-125 is not specific for ovarian cancer and may be elevated in a number of other malignancies, menstruation, endometriosis, pregnancy, benign ovarian tumours and pelvic inflammatory disease
  • The main use of CA-125 is in assessing response over time to treatment for malignancy

• Any cyst not positively identified as non-neoplastic should be removed, as seemingly benign tumours may be malignant.
• In younger women cystectomy may be preferable to oophorectomy.
• In post-menopausal women, if one ovary is pathological then both are removed.

Expectant management

• With periodic reassessment by ultrasound for a maximum of 3 months.
• Appropriate for asymptomatic cysts unremarkable by ultrasound.
• Many tumours resolve spontaneously within two to three cycles.

Oral contraceptives

• For asymptomatic cysts unremarkable by ultrasound for a maximum of three cycles.
• Very effective in preventing formation of functional tumours but their use in shrinking or resolving cystic tumours has not been proven.

Surgery

• If conservative measures fail or criteria for surgery are met, surgical therapy for benign ovarian tumours is generally very effective and provides a cure with minimal effect on reproductive capacity.
• For symptomatic cysts or if an asymptomatic cyst does not resolve within several cycles and the there is any doubt as to the benign or malignant nature of the tumour, removal of the tumour or the entire ovary may be required.
• Laparoscopic surgery for benign ovarian tumours is associated with reduced risk of any adverse effect of surgery, reduced pain, and fewer days in hospital compared to laparotomy, in the small number of studies identified. There was no difference between the procedures with regard to outcomes of fever, post operative infections and tumour recurrence.^2,3
• Ovarian torsion:⁴
  • Usually initially treated by laparoscopy with uncoiling of the affected ovary and possible oophoropexy.
  • Salpingo-oophorectomy may be indicated if there is severe vascular compromise, peritonitis or tissue necrosis.
• Immediate surgical intervention is indicated for haemorrhagic cyst.
• Laparoscopy will need to be upgraded to laparotomy when malignancies are discovered.
• Pseudomyxoma peritonei is treated by surgical debulking.

• Haemorrhage is more common for tumours of the right ovary.
• There is an increased risk of spontaneous abortion with haemorrhagic cysts.
• Infertility often occurs as a result of ovarian tumours or their treatment.

• Variable and depends on the type and size of tumour, associated complications and patient's age.
• Most ovarian cysts in premenopausal women will resolve spontaneously or with hormonal therapy.
• Ovarian torsion: if operated within 6 hours of onset of symptoms, tissue will remain viable.
• Prognosis of surgically removed cysts ultimately depends on the histology.

• Functional cysts can be inhibited by oral contraceptive therapy.⁵