Theca Lutein Cyst

Theca lutein cysts are bilateral, multiple, thin walled, fluid filled ovarian cysts lined by luteinised theca interna cells. They arise from exaggerated ovarian stimulation by human chorionic gonadotrophin (hCG), or from increased ovarian sensitivity to it. They are benign and self-limited.

They are found in conditions with high hCG:

• molar pregnancy and choriocarcinoma (20 to 50 percent)
• multiple pregnancy
• fetal hydrops with large placenta
• pregnancies with diabetes
• ovulation induction (clomifene, gonadotrophins), where they form part of ovarian hyperstimulation syndrome

Less often they occur in normal pregnancy and in polycystic ovary syndrome. They also occur with hypothyroidism (high TSH acting at the FSH receptor) and with FSH-receptor mutations that cause spontaneous ovarian hyperstimulation in pregnancy.

The ovaries enlarge to 5 to 30 cm, with a multicystic "spoke wheel" appearance.

• Often asymptomatic, found on ultrasound in early pregnancy, at hydatidiform mole evacuation, or at caesarean section.
• Abdominal distension and pelvic discomfort, nausea, vomiting.
• Complications: torsion (sudden severe pain), rupture with haemoperitoneum, haemorrhage into a cyst, and in severe cases the features of ovarian hyperstimulation syndrome: ascites, pleural effusion, haemoconcentration, oliguria.
• Maternal virilisation (hirsutism, clitoromegaly, voice deepening) is rare and arises from androgen secretion in the second half of pregnancy; fetal virilisation of a female fetus can follow. Androgen levels are raised (testosterone often above 5 nmol/L), and the condition resolves after delivery.
• Examination: bilateral adnexal masses, tender when torsion or bleeding occurs.

• Ultrasound: markedly enlarged ovaries, both sides, with many large thin walled cysts separated by thin septa, preserved ovarian stroma at the periphery, and no solid papillary projections; Doppler shows normal flow unless torsion.
• Serum hCG (markedly raised in molar pregnancy, choriocarcinoma or multiple pregnancy); TSH and free thyroxine to exclude hypothyroidism.
• Testosterone, androstenedione and DHEAS if virilisation is present, to distinguish from a luteoma or a virilising tumour (sex hormone secreting tumours are usually unilateral and solid, with testosterone often above 10 nmol/L and persistent postpartum).
• CA-125 may be mildly raised in pregnancy and is of limited value; MRI is used to assess complex cysts in pregnancy.
• Exclude ovarian neoplasm: bilaterality, thin walls and the clinical context favour theca lutein cysts.

• Conservative management is the rule because the cysts regress spontaneously over 2 to 4 months after hCG falls (after evacuation of a mole, delivery or discontinuation of stimulation), with ultrasound every 4 to 6 weeks until they resolve. Avoid surgery because of the risk of removing functioning ovary and because they respond to removal of the cause.
• Analgesia: paracetamol 1 g every 6 hours; avoid non-steroidal anti-inflammatory drugs in pregnancy, and avoid strenuous activity and intercourse.
• Molar pregnancy: suction evacuation, then serial hCG until normal; cysts regress with the hCG fall. Persistent trophoblastic disease: chemotherapy (methotrexate 50 mg intramuscular on days 1, 3, 5, 7 with folinic acid 15 mg orally on days 2, 4, 6, 8, repeated every 14 days).
• Hyperstimulation: supportive treatment with intravenous fluids, albumin, thromboprophylaxis with enoxaparin 40 mg subcutaneously daily, and paracentesis for tense ascites.
• Hypothyroidism: levothyroxine, starting at 1.6 micrograms/kg daily (lower in elderly and cardiac disease), titrated to normal TSH; cysts regress with thyroid replacement.
• Torsion or haemorrhage: laparoscopy with detorsion and ovarian conservation, drainage by aspiration of large cysts if needed; oophorectomy only if necrosis is established and irreversible, since the ovary may recover even when it appears dusky.
• Virilisation in pregnancy: observation, with monitoring of fetal anatomy in a female fetus; resolution follows delivery. Persistent virilisation after delivery suggests a tumour.
• Prognosis is excellent; no malignant potential.