Ovarian germ cell tumours

Overview

Ovarian germ cell tumours (OGCTs) are a group of growths that develop from the germ cells of the ovary — the same cells that would normally mature into eggs (ova). Because these are the body’s most versatile “primitive” cells, capable of producing many different tissue types, germ cell tumours can contain a surprising variety of structures, including hair, fat, cartilage, bone and even teeth.

Several important facts set germ cell tumours apart from the more common epithelial ovarian cancers:

• They typically affect children, teenagers and young women, unlike epithelial ovarian cancer, which usually occurs after 50.
• The large majority (around 95%) are benign (non-cancerous).
• Even the malignant forms are among the most curable cancers of the ovary, with most patients going on to live full, healthy lives — and often retain their fertility.
• They tend to grow quickly and are usually detected at an early stage, while still confined to one ovary.

Who Gets Ovarian Germ Cell Tumours?

Germ cell tumours account for roughly 20% of all ovarian growths, but only about 2–3% of all ovarian cancers in Western populations. Their frequency varies worldwide — they represent a higher proportion of ovarian cancers in some Asian and African populations.

Key demographic features:

• Peak age: adolescence and early adulthood, most commonly between 10 and 30 years
• Malignant forms are most frequent between 15 and 19 years of age
• They are the most common ovarian tumours found in girls and women under 20
• They are rare after the menopause
• About 60–75% of malignant cases are diagnosed at stage I (confined to the ovary)

Risk factors are not well defined, but recognised associations include:

• Gonadal dysgenesis (abnormally developed ovaries), for example in Turner syndrome or Swyer syndrome — these individuals have a significantly higher risk of developing dysgerminoma or gonadoblastoma
• Rare genetic syndromes affecting sex development (differences of sex development)
• No strong links to lifestyle factors, pregnancy history or contraceptive use have been established

Types of Ovarian Germ Cell Tumours

The World Health Organization (WHO) classifies germ cell tumours according to the type of tissue they form. The most important distinction is between benign and malignant types.

Benign Tumours

Mature cystic teratoma (dermoid cyst) is by far the most common germ cell tumour — and the most common ovarian tumour overall in young women. It contains fully developed, “mature” tissues such as skin, hair, sebum (oily material), teeth and bone. Around 10–15% occur in both ovaries at once. Although benign, it can cause pain or complications (torsion, rupture) and is usually removed surgically.

Malignant Tumours

How Does It Look?

One of the most striking features of germ cell tumours is their appearance — both to the naked eye and on medical imaging. Because germ cells can form almost any body tissue, these tumours often look very different from ordinary ovarian cancers.

To the Naked Eye (Gross Appearance)

• Mature cystic teratoma (dermoid cyst): Usually a smooth-walled cyst filled with thick, greasy sebaceous material and matted hair. When opened, it may contain fully formed teeth, bone, cartilage or thyroid tissue. A solid lump on the inner wall (called the Rokitansky nodule) is typical.
• Dysgerminoma: A solid, fleshy, lobulated mass with a uniform grey, cream or pinkish-tan surface. It tends to be softer than other ovarian tumours.
• Immature teratoma: Predominantly solid and bulky, with a variegated appearance — areas of soft fleshy tissue mixed with small cysts, zones of bleeding (haemorrhage) and tissue death (necrosis).
• Yolk sac tumour: Typically large and fragile, with a grey-yellow, jelly-like (gelatinous) cut surface, often showing prominent haemorrhage and necrosis.

Size and Laterality

• Malignant germ cell tumours are often large at diagnosis — commonly 10–20 cm across — because they grow rapidly.
• Most malignant types affect only one ovary; the exception is dysgerminoma, which involves both ovaries in 10–15% of cases.

Under the Microscope

• Dysgerminoma shows sheets of large, uniform cells separated by thin bands of tissue containing lymphocytes (a hallmark feature).
• Yolk sac tumour shows characteristic structures called Schiller–Duval bodies, which resemble tiny primitive glomeruli, along with pink hyaline globules.
• Immature teratoma is graded 1 to 3 according to how much immature neural tissue it contains — this grading helps guide treatment.

On Imaging

• Ultrasound: A dermoid cyst classically appears as a complex cyst with a highly echogenic (bright) nodule, shadowing from fat or calcification, and hair-fat levels. Malignant tumours typically appear as large solid or mixed solid–cystic masses with rich blood flow on Doppler.
• CT and MRI show the size, internal structure (fat, calcification, solid areas) and any spread into the abdomen or lymph nodes. Calcifications and fat are characteristic clues pointing to a teratoma.

Symptoms

The symptoms of ovarian germ cell tumours are usually caused by the rapid growth and stretching of the ovarian capsule, pressure on neighbouring organs, or complications such as twisting (torsion) or rupture. Because these tumours grow quickly, symptoms often appear over weeks rather than months.

Common Symptoms

• Abdominal or pelvic pain — the single most common symptom, present in the majority of patients
• Abdominal swelling or distension — clothes may suddenly feel tight around the waist
• A palpable lump or mass in the lower abdomen, sometimes felt by the patient or a parent
• A sensation of fullness, pressure or heaviness in the pelvis

Acute (Emergency) Symptoms

Around 10–15% of patients present as emergencies because of complications:

• Sudden, severe, sharp pelvic pain — a warning sign of ovarian torsion (the ovary twisting on its blood supply), rupture of the tumour, or bleeding into the tumour
• Pain accompanied by nausea and vomiting
• Fever, faintness or signs of internal bleeding (rare)

Any sudden, severe lower abdominal pain in a girl or young woman requires urgent medical assessment.

Hormonal and General Symptoms

• Menstrual irregularities or absence of periods (amenorrhoea)
• Preocious (early) puberty in young girls with hormone-producing tumours (e.g. vaginal bleeding, breast development before age 8)
• Symptoms mimicking pregnancy (nausea, missed periods) in hCG-producing tumours
• Frequent urination or difficulty passing urine (pressure on the bladder)
• Constipation or altered bowel habit (pressure on the bowel)
• Unintentional weight loss, fatigue or loss of appetite in advanced disease
• Back pain or leg swelling if the tumour presses on pelvic nerves or veins

Important:** These symptoms are far more often caused by harmless conditions than by cancer. However, persistent or worsening symptoms — especially pain combined with abdominal swelling — should always be checked by a doctor.

How Is It Diagnosed?

Diagnosis usually involves a combination of history, imaging and blood tests, and is confirmed by examining tissue after surgery.

1. Medical History and Examination

The doctor will ask about symptoms, periods and development, and may perform an abdominal (and in adults, sometimes pelvic) examination.

2. Imaging

• Transvaginal or transabdominal ultrasound — the first-line test; in children, scans are performed via the abdomen
• MRI — helpful for characterising the mass and planning fertility-sparing surgery
• CT scan of the abdomen, pelvis and chest — used to look for spread (staging)

3. Blood Tests (Tumour Markers)

Specific markers are central to diagnosing and monitoring germ cell tumours:

Pregnancy must be excluded when hCG is elevated.

4. Surgery and Pathology

In most cases, the definitive diagnosis is made after surgical removal of the tumour, when a pathologist examines it under the microscope. Because most patients are young women who wish to preserve fertility, the surgeon usually aims to remove only the affected ovary rather than the whole reproductive system.

Staging

Staging describes how far the tumour has spread and is determined during surgery (FIGO system). It applies to malignant tumours only.

Reassuringly, the majority of patients are diagnosed at stage I.

Treatment

Treatment depends on the type, stage and grade of the tumour, and on the patient’s age and desire to preserve fertility. Care is usually planned by a multidisciplinary team including gynaecological oncologists, oncologists and specialist nurses.

Surgery

• Fertility-sparing surgery is the standard approach for young patients: removal of the affected ovary and its tube (unilateral salpingo-oophorectomy) while leaving the healthy ovary and uterus in place.
• Staging surgery includes taking washings from the abdomen, biopsies of the abdominal lining, removal of the omentum (fatty apron in the abdomen) and sampling of lymph nodes.
• For patients who have completed their family, or in extensive disease, a more complete removal of both ovaries, tubes and uterus may be recommended.
• Any remaining disease after initial surgery may be removed at a later operation, particularly in teratomas.

Chemotherapy

Most malignant germ cell tumours are highly sensitive to chemotherapy. The standard regimen is BEP — a combination of:

• Bleomycin
• Etoposide
• Platis (cisplatin)

Typically 3–4 cycles are given. Exceptions that may be managed with surgery and careful surveillance alone include stage I dysgerminoma and stage I, grade 1 immature teratoma.

Radiotherapy

Dysgerminoma is extremely sensitive to radiation, but radiotherapy is now rarely used because it damages fertility and chemotherapy is equally effective.

Treatment Summary by Type

Prognosis (Outlook)

The outlook for ovarian germ cell tumours is generally excellent, among the best of any gynaecological cancer:

• Benign dermoid cysts are cured by surgery in almost all cases.
• Stage I malignant tumours: cure rates exceed 95%.
• Advanced-stage disease: even when the cancer has spread, modern chemotherapy achieves long-term cure in 80–90% or more of patients.
• Dysgerminoma is particularly favourable; yolk sac tumours and choriocarcinomas are more aggressive but still respond well to BEP chemotherapy.

Recurrent disease can often still be successfully treated. Some immature teratomas recur as mature tissue (“growing teratoma syndrome”) — these masses are benign in behaviour but may need surgical removal if they enlarge.

Fertility and Life After Treatment

Because most patients are of childbearing age, protecting future fertility is a central goal:

• Most patients keep one healthy ovary and the uterus, so natural conception is usually possible.
• BEP chemotherapy causes less damage to ovarian function than many other cancer treatments; periods typically return within months, and many survivors go on to have healthy pregnancies.
• Options such as egg or embryo freezing can be discussed before treatment where appropriate.
• Follow-up includes regular examinations, tumour marker blood tests and imaging for at least 2–5 years, since most recurrences occur within the first 2 years.
• Some patients experience chemotherapy-related side effects (fatigue, hearing changes from cisplatin, lung effects from bleomycin) — these are monitored during and after treatment.

When to See a Doctor

Seek medical advice if you or your child experience:

• Persistent or worsening abdominal or pelvic pain lasting more than a few weeks
• Abdominal swelling or a noticeable lump
• Unexplained changes in periods, or bleeding before puberty or unexpectedly
• Sudden severe pelvic pain — attend an emergency department immediately, as this may signal torsion, which requires urgent surgery to save the ovary

Key Points to Remember

• Ovarian germ cell tumours arise from egg-producing cells and mostly affect girls and young women.
• Most are benign dermoid cysts; malignant forms are rare but highly curable.
• The most common symptom is abdominal pain, often with swelling.
• Treatment usually involves fertility-sparing surgery, with BEP chemotherapy where needed.
• Cure rates are excellent, and most survivors can go on to have children.

References

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Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition.