Teratomas In Unusual Locations: Ovaries, Testes, And Mediastinum


Teratomas are rare abnormal cell growths that mainly start to grow from the cells responsible for reproduction e.g. sperm and eggs. This type of abnormal reproductive cell growth (i.e. neoplasm) is medically known as a germ cell tumour.  The National Cancer Institute (US) broadly defines teratomas as neoplasms that are either mature or immature cells forming tissues consisting of hair, muscle, bone or teeth.1

Teratomas most frequently occur in the reproductive organ - ovaries or testes in young adults but can also be found in newborns or infants in their tailbone. They can also occur in more unusual locations such as the mediastinum - the cavity between the two lungs.

Teratomas in ovaries

Background and incidence

Research through the years has found that nearly a quarter of abnormal tissue growths found on ovaries originate from germ cells.2 Germ cells are the cells found in the reproductive organs that make eggs and sperm thus they are responsible for reproduction. Often these germ cell teratomas will be diagnosed as cystic ovarian teratomas - almost 20%.3 They often don’t cause cancerand can be easily treated by surgical removal. Cancerous ovarian teratomas  only occur 1% of the time.3

Ovarian teratomas are usually diagnosed from puberty going up,4 with a 45-year-old woman being the oldest case of ovarian teratoma3Although widely researched, it is still widely unknown how or why ovarian teratomas form.

Clinical presentation

Ovarian teratoma symptoms aren’t specific, they are usually foundduring a physical examination for another disease or tumour e.g. during a cesarean examination.5

Symptoms can include but are not limited to:

  • Irregular periods
  • Recurring lower abdominal pain
  • Difficulty urinating
  • Bloating
  • Increase in abdomen size
  • Vaginal bleeding

There have also been cases of asymptomatic cases where as mentioned before the teratoma is found incidentally.

Diagnostic evaluation

The initial assessment of a patient presenting with  symptoms is to do a medical history and physical examination. It is important to rule out the presence of other diseases or illnesses before making a final decision due to the non-specific nature of symptoms most commonly associated with ovarian teratomas. 

A history will explore any risk factors that may lead to the development of ovarian teratomas. A population-based study conducted in the UK identified a few risk factors such as a delayed start to menstruation, alcoholism, a previous history of teratomas and infertility.6 These alone do not determine the presence of ovarian teratoma and further diagnostic tests must be conducted. 

A physical examination will look for the presence of any masses in the pelvic region.Afterwards, imaging tests such as an ultrasound are the standard way of diagnosing ovarian teratoma.7

Other imaging tools are also available such as a CT scan and MRI imaging which generally provide more detailed visuals of the pelvic and abdominal region to better determine the extent of the neoplasm growth.3

Some blood tests can also be conducted to aid in diagnosis. However, teratomas do not exhibit specific serum tumor markers so a blood test will always be used in combination with an ultrasound or CT scan.3

Treatment options

Treating ovarian teratomas varies and depends on a few factors such as the malignancy (the cancerous nature) of the teratoma, patient’s desire for fertility preservation, age and extent of the tissue growth. As an overview, the National Cancer Institute (NCI) categorizes treatment options into four:

  1. Surgical removal
  2. Radiotherapy
  3. Chemotherapy
  4. Bone marrow transplantation with chemotherapy

As ovarian teratoma mainly affects younger women of childbearing potential, surgical management will seek to preserve fertility. The gynaecologist will remove the affected ovary or attempt to remove the abnormal growth to preserve the function of your ovaries.4

In more severe cases where the teratoma is cancerous or has spread outside of the ovaries, chemotherapy may be considered. The type of chemotherapy varies and depends on the type of teratoma. Radiotherapy is generally only considered if  intial treatment fails.3

It is important to remember that each patient is different and so each disease state is different. Your surgeon or doctor will assess the individual factors in your case and will then tailor your treatment regimen to you.

Prognosis and follow-up

The prognosis and follow-up after treatment depends on the type of teratoma and any complications. Treatment of benign teratomas has shown excellent prognostic results with a very small chance of recurrence a study showed a small risk of recurring again after 2-10 years following successful treatment.3

Malignant teratomas depend on the stage of teratoma and the extent of growth. Diagnosing and treating early-stage malignant ovarian teratoma has better prognostic results than late-stage.  Depending on the severity of the teratoma, chemotherapy may be required after surgical management of malignant teratomas.4

Teratomas in testes

Background and incidence

Testicular teratomas are the most common type of cancer affecting the testes8. This type of cancer starts in the sperm-producing germ cells. The World Health Organization classifies testicular teratomas into two separate groups:9

  1. Germ cell neoplasia in situ (GCNIS)
  2. Non-germ cell neoplasia in situ (NGCNIS)

The main difference between these two main classifications is that GCNIS teratomas have metastatic potential. This type of teratoma grows from abnormal germ cells found within small testicular tubules. Cancer Research UK estimates that around 50% of men diagnosed with GCNIS will develop cancer within 5 years.10

NGCNIS teratomas are uncommon, not aggressive and typically benign in nature. Yolk-sac tumours and embryonal carcinoma are examples of NGCNIS tumours.

Testicular teratomas are mainly diagnosed in young children and adults - the mean age group of diagnosis is 20-35 years.8

Clinical presentation

The most apparent waytesticular teratomas shows is through a swelling or a lump in the testicles. Some other symptoms include:10

  • Lump and/or swelling in testicles
  • Bleeding or blood clots
  • Pain in testicles
  • Hard or heavy skin (scrotum)

These symptoms are non-specific to cancer therefore a patient presenting with any one of these symptoms most likely does not have cancer. Further diagnostic tests will need to be completed to diagnose and rule out other diseases or ailments.

Diagnostic evaluation

Like other germ cell tumours, a series of imaging diagnostic tools and blood tests will need to be completed to diagnose.

Blood tests will be done to check for tumour markers. An increased presence of these tumour markers will indicate the stage of the disease. A full-blood count may also be done to check for red blood cell and white blood cell count.10

Ultrasound scans are the gold standard for diagnosing most cancers. Ultrasounds create images that differentiate between a cancerous or non-cancerous lump on the testes.10

MRI scans are not commonplace in diagnosing cancers and are usually only used in more complex clinical presentations.11

Treatment options

The treatment options for testicular teratomas vary and depend on a number of factors such as the type of tumour, whether it has spread, the risk of recurrence, general well-being and the age of the patient.10

Surgery is the standard treatment for testicular teratomas where the affected testicle is removed. This surgery is known as orchiectomy. Most testicular teratomas can develop into more aggressive cancers and more than likely will recur if left untreated. 

Chemotherapy may be considered after surgery but that depends on the chances of the tumour recurring again which is confirmed with a serum test for tumour markers. It may also be considered if the teratoma was already malignant in nature and had spread to other organs e.g. lymph nodes.

Radiotherapy is generally considered in more developed cases such as Stage 2 teratomas. However, it is never used as a stand-alone treatment and will only be used together with  surgery and/or chemotherapy.11

Prognosis and follow-up

Overall, more localized teratomas have a better prognostic result and outcome than metastatic teratomas. Adults with localized teratomas have a survival rate estimated at nearly 100% after 5 years.11 The survival rate drops, the higher the percentage of presence of teratomas.

Follow-ups with your doctor after treatment are very important. These follow-up appointments will ensure that if the tumour was to recur again, then with early detection it can be eradicated usually with chemotherapy with no further complications.

It is important that any changes such as a new lump or swelling, any bleeding or pain is reported as soon as possible to your doctor. It often is not cancer-related but it is still important to rule this out with your doctor.

Teratomas in mediastinum

Background and incidence

The mediastinum is the area occupied by many vital organs found between the two lungs as defined by the National Cancer Institute.12 Tumours found in this area are very rare but are the most common extra-gonadal location where germ cell tumours are found - approximately 5-10% of germ cell tumours are mediastinal.13

A population study conducted in 2020 found that 27% of mediastinal tumours have a malignant nature.  In addition, the same study reported that most of the population affected by malignant mediastinal teratomas are between the ages of 18 to 39 years.14

Clinical presentation

Similar to gonadal teratomas, mediastinal teratomas tend to be discovered incidentally due to their non-specific symptoms or the lack of symptoms observed in patients. However, symptoms tend to develop after some while some of which include:15

  • Shortness of breath
  • Chest pain
  • Abnormal lump in neck
  • Persistent dry cough
  • Recurring chest infections

Diagnostic evaluation

Imaging is important in diagnosing teratomas. Chest CT scans are the gold standard for identifying and diagnosing mediastinal masses. Chest X-rays can also be used but will only show the presence of a mass and not the extent and nature of the mass.16 Additionally, serum tumour markers will also provide a good indication of the presence of cancerous cells in the mediastinum.15

Treatment options

Due to the close position  of mediastinal teratomas to vital organs, surgery tends to be the preferable treatment option. Malignancy of this type of teratoma can lead to the collapse and rupture of vital organs found in the mediastinum therefore surgical incision is the standard treatment.16

Chemotherapy is typically considered after operations  if serum tumour markers are increased.

Prognosis and follow-up

Due to the majority of benign nature of mediastinal teratomas, the prognostic rate is favourable. A three-year survival rate greater than 80% is typically achieved.17

After treatment, regular checkups will be done with your doctor to ensure that if the tumour comes back then it can be detected early. This may include regular chest X-rays. It is important that any new or changes in symptoms are reported to your doctor for follow-up.

Unique considerations and challenges

Age-related factors

Overall, age is not a risk factor in developing germ cell teratomas. However, in most cases and patients it is usually diagnosed in early childhood or young adolescence. In addition to germ cell teratomas being rare, only 3.5% of childhood cancers are germ cell teratomas.18 In young adults presenting with neoplasms, only 13.9% is due to germ cell teratomas.18

Surgical approaches and complications

In most types of teratomas, surgical incision or even removal is the gold standard. This is to decrease the chance of recurrence of the neoplasm. However, complications can follow some surgical approaches.

In ovarian teratomas, oophorectomy is the preferred option which is the removal of one or both ovaries. In this surgical approach, chemical peritonitis is a very rare complication. This occurs when the teratoma causes a chemical spillage of its contents into the surrounding abdominal cavity. Although rare, it is very difficult to treat and manage afterwards.19

Fertility and reproductive implications

The effect on fertility varies for the type of germ cell teratoma. The removal of one ovary means that fertility and menstruation are not impacted due to the ovarian reserve of the remaining ovary. However, in testicular teratoma, fertility will be impacted.20

The impact on reproduction and fertility must be discussed with your doctor before commencing treatment so as to discuss the available treatment options to spare fertility e.g. sperm banking. 

Malignant transformation risk

The risk of a teratoma developing malignancy is generally quite rare. However, many reports have found that although rare in nature, teratomas with malignant transformation have poor prognosis and can be unresponsive to chemotherapy and radiotherapy.21 Unfortunately, due to the aggressive nature of malignant teratomas, surgical removal is the mainstay treatment. 

Long-term follow-up and surveillance

There is no definitive length of follow-up and surveillance required for patients that have been treated for germ cell teratomas. However, immediately following treatment follow-up scans and appointments will be conducted to ensure early detection in case of recurrence.

It is important that you report any new or sudden changes in symptoms to your doctor.


The overall outcome of a diagnosis with teratoma, especially germ cell teratoma is dependent on early diagnosis. Although the symptoms can be non-specific and will need further tests to differentially diagnose it is nonetheless important to report any concerning and unexplained symptoms that you may notice. Many people live fulfilling lives with cancer. Treatment options have evolved over time and are very successful. 


  1. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/teratoma [Internet]. 2011 [cited 2023 Jul 3]. Available from: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/teratoma
  2. Hackethal A, Brueggmann D, Bohlmann MK, Franke FE, Tinneberg HR, Münstedt K. Squamous-cell carcinoma in mature cystic teratoma of the ovary: systematic review and analysis of published data. Lancet Oncol. 2008 Dec;9(12):1173–80.
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  6. Westhoff C, Pike M, Vessey M. Benign ovarian teratomas: a population-based case-control study. Br J Cancer [Internet]. 1988 Jul [cited 2023 Jul 5];58(1):93–8. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2246492/
  7. Outwater EK, Siegelman ES, Hunt JL. Ovarian teratomas: tumor types and imaging characteristics. RadioGraphics [Internet]. 2001 Mar [cited 2023 Jul 5];21(2):475–90. Available from: http://pubs.rsna.org/doi/10.1148/radiographics.21.2.g01mr09475
  8. Types of testicular cancer [Internet]. 2019 [cited 2023 Jul 6]. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/testicular-cancer/types-of-testicular-cancer
  9. Berney DM, Cree I, Rao V, Moch H, Srigley JR, Tsuzuki T, et al. An introduction to the WHO 5th edition 2022 classification of testicular tumours. Histopathology. 2022 Oct;81(4):459–66
  10. Types of testicular cancer [Internet]. [cited 2023 Jul 6]. Available from: https://www.cancerresearchuk.org/about-cancer/testicular-cancer/types
  11. Farci F, Shamsudeen S. Testicular teratoma. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Jul 6]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK567728/
  12. Https://www. Cancer. Gov/publications/dictionaries/cancer-terms/def/mediastinum [Internet]. 2011 [cited 2023 Jul 7]. Available from: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/mediastinum
  13. Teratomas and other germ cell tumors of the mediastinum: practice essentials, anatomy, pathophysiology. 2021 Aug 3 [cited 2023 Jul 7]; Available from: https://emedicine.medscape.com/article/427395-overview
  14. Wang R, Li H, Jiang J, Xu G. Incidence, treatment, and survival analysis in mediastinal malignant teratoma population. Translational Cancer Research [Internet]. 2020 Apr [cited 2023 Jul 7];9(4). Available from: https://tcr.amegroups.com/article/view/37592
  15. Tian Z, Liu H, Li S, Chen Y, Ma D, Han Z, et al. Surgical treatment of benign mediastinal teratoma: summary of experience of 108 cases. Journal of Cardiothoracic Surgery [Internet]. 2020 Feb 17 [cited 2023 Jul 7];15(1):36. Available from: https://doi.org/10.1186/s13019-020-1075-8
  16. No TH, Seol SH, Seo GW, Kim DI, Yang SY, Jeong CH, et al. Benign mature teratoma in anterior mediastinum. J Clin Med Res [Internet]. 2015 Sep [cited 2023 Jul 7];7(9):726–8. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4522994/
  17. Danaher L. Radiopaedia. [cited 2023 Jul 7]. Mediastinal teratoma | radiology reference article | radiopaedia. Org. Available from: https://radiopaedia.org/articles/mediastinal-teratoma?lang=gb
  18. Fonseca A, Frazier AL, Shaikh F. Germ cell tumors in adolescents and young adults. JOP [Internet]. 2019 Aug [cited 2023 Jul 7];15(8):433–41. Available from: https://ascopubs.org/doi/10.1200/JOP.19.00190
  19. Sinha A, Ewies AAA. Ovarian mature cystic teratoma: challenges of surgical management. Obstet Gynecol Int [Internet]. 2016 [cited 2023 Jul 7];2016:2390178. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4823513/
  20. Kurt S, Aytuğ Avşar H, Erbil Doğan Ö, Saatli HB, Saygılı U. Effects of mature cystic teratoma on reproductive health and malignant transformation: A retrospective analysis of 80 cases. J Turk Ger Gynecol Assoc [Internet]. 2019 Jun [cited 2023 Jul 7];20(2):84–8. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6558361/
  21. Wang J, Kazmi SAJ. Teratoma with malignant transformation: a case report with pathological, cytogenetic, and immunohistochemistry analysis. Sarcoma [Internet]. 2011 Jun 9 [cited 2023 Jul 10];2011:e450743. Available from: https://www.hindawi.com/journals/sarcoma/2011/450743/
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Masters of Pharmacy – Mpharm, University of Hertfordshire, England

Sara is a skilled pharmacist with a solid foundation in clinical knowledge, understanding medications, disease states and treatment options. She has years of experience developing her career within different sectors of pharmacy, from training to managerial roles. As a pharmacist and thereby a medication safety expert, Sara has considerable skills effectively communicating and presenting complex medical information that is both accessible and scientifically accurate to the general public and specific patient groups.

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