Teratomas: Tumors with Teeth and Other Tissues

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By Dr. Priyom Bose, Ph.D.Reviewed by Danielle Ellis, B.Sc.

What are teratomas?
Types of teratomas
Teratomas: Symptoms and diagnosis
Treatment options for teratomas and ongoing research
References
Further reading

Teratomas are embryonal tumors that arise in the germ cells and contain different types of tissues, including bone, teeth, hair, and muscle.1 Scientists have classified teratomas as a rare type of germ cell tumor (GCT).2 Although most teratomas are benign, they can be malignant as well.

What are teratomas?

Although scientists had been curious about teratomas for centuries, they only started deciphering these strange growths in the 1960s.1 Research on teratomas also led to a better understanding of the normal functions of germinal cells.

“Teratoma” is a Greek word for “monstrous tumor” due to the possibility that these tumors sometimes contain bone, hair, teeth, neurons, and even eyes.3 In rare cases, these tumors may even contain remnants of complex body parts (e.g., lungs, brains, liver, and thyroid glands).

Teratomas contain tissues that are either foreign to the area where they developed or tissues derived from all three embryonic layers, namely, endoderm, mesoderm, and ectoderm.4 They occur due to any disruptions during the cell differentiation process. The unspecialized germ cells differentiate into different types of specialized cells, such as blood cells, muscle cells, and nerve cells. This is why teratomas contain random body parts and tissues. 3D illustration of teratoma or other tumor of the testis

Image Credit: Kateryna Kon/Shutterstock.com

In humans, teratomas mostly form in gonads, i.e., ovaries and testes. However, these tumors may also develop in the retroperitoneum and anterior mediastinum.5

Types of teratomas

Teratomas have been divided into two types: mature and immature.6 Mature teratomas are well-differentiated and similar to the germ cell layers, while immature teratomas exhibit incomplete differentiation relative to embryonic or fetal tissues.

Mature teratomas:

Mature teratomas are usually composed of different types of tissues, such as muscle, bone, and hair.7 These types of teratoma occur in the testicles or ovaries at the start of puberty or tailbone in newborns. Mature teratomas are also called dermoid cysts.

Histological studies revealed that cells of mature teratomas are similar to those of normal cells under the microscope. Mature teratomas could synthesize hormones or enzymes that may manifest as disease symptoms. Although this type of tumor is benign, it might come back after being surgically removed.

Immature teratoma:

An immature teratoma occurs more frequently in young women and is composed of three germ cell layers. It is the second most frequent malignant germinal tumor after dysgerminoma. Based on the presence and proportion of immature neuroepithelial tissue, immature teratoma has been graded ranging between 1 and 3.8

Immature teratoma can be present in the ovary, testicle, mediastinum, sacrococcygeal region, head and neck, and rarely in intracranial locations. Although it can be easily determined in children and adult females, it isn’t easy to detect in post-pubertal males.

Teratocarcinomas are malignant, immature teratomas that occur at the testicles. They contain both embryonal carcinomas (EC) and teratomas. EC cells are undifferentiated malignant stem cells that give rise to varied tissue types of teratocarcinoma.

Teratomas: Symptoms and diagnosis

The symptoms of teratoma vary based on the tumor’s location and size. These symptoms are also based on slightly elevated levels of hormones (beta-human chorionic gonadotropin-BhCG) and tumor markers (alpha-fetoprotein-AFP).9

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Since most symptoms associated with teratomas are similar to other tumor types, it is not always easy to diagnose them promptly. In many instances, teratoma has been detected by accident. For example, surgeons may detect teratoma in the ovary while performing a cesarean section.

Individuals with ovarian teratoma develop abdominal pain because the tumor incurs excessive pressure on the ovary. In some cases, this type of teratoma occurs along with anti-N-methyl-D-aspartate (NMDA) receptor encephalitis, causing symptoms such as severe headache, psychosis, and confusion. Abdominal teratomas may present as abdominal distension with lumps in the abdomen along with signs of intestinal obstruction. 10

Teratomas are mostly asymptomatic at the time of diagnosis and are incidentally detected via imaging tests, such as X-rays, magnetic resonance imaging (MRI), computed tomography (CT) scans, and ultrasound.9 Imaging techniques help determine the size and location of teratoma. Detection of fat attenuation inside of a cyst also helps diagnose teratoma.

What are the Recent Developments in Medical Imaging?

Blood tests are also conducted to assess the hormone levels and detect tumor markers. Clinicians recommend a biopsy to confirm whether the teratoma is malignant or benign.

Treatment options for teratomas and ongoing research

Teratomas are removed through surgical procedures.9 It is important to remove these tumors even when it is diagnosed to be benign because they could grow or rupture, leading to a more complex condition. Malignant teratomas are treated by chemotherapy, radiation therapy, and chemoradiation, which is a combination of chemotherapy and radiation therapy.11 In most cases, people with benign or even malignant teratoma have exhibited excellent survival rates with early diagnosis and treatment.

Currently, scientists are focused on exploring efficient prenatal diagnosis of teratoma and on understanding teratoma recurrence and treatment.

References

Raup C. Teratomas. Embryo Project Encyclopaedia. 2010; Available at: https://embryo.asu.edu/pages/teratomas
McKenney JK, et al. Extragonadal germ cell tumors: a review with emphasis on pathologic features, clinical prognostic variables, and differential diagnostic considerations. Adv Anat Pathol. 2007;14(2):69-92. doi: 10.1097/PAP.0b013e31803240e6..
AlQattan AS. et al. The “Monstrous tumor” of Adrenal gland: A case report and review of literature on adrenal teratomas. International Journal of Surgery Open. 2023; 60, 100696. doi.org/10.1016/j.ijso.2023.100696
Plazibat M, et al. Embryo-derived teratoma in vitro biological system reveals antitumor and embryotoxic activity of valproate. FEBS J. 2020;287(21):4783-4800. doi: 10.1111/febs.15248.
Ahmed A, Lotfollahzadeh S. Cystic Teratoma. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024. Available at: https://www.ncbi.nlm.nih.gov/books/NBK564325/
Eslami M, et al. Mature teratoma of conus medullaris: A case report and review of literature. Clin Case Rep. 2023;11(9):e7966. doi: 10.1002/ccr3.7966.
Hattab EM. (Germ Cell Tumors. Practical Surgical Neuropathology. 2010; 333-351. doi.org/10.1016/B978-0-443-06982-6.00015-8
Moraru L, et al. Immature Teratoma: Diagnosis and Management-A Review of the Literature. Diagnostics (Basel). 2023;13(9):1516. doi: 10.3390/diagnostics13091516.
Rogers, K. (2024,). teratoma. Encyclopedia Britannica. https://www.britannica.com/science/teratoma
Rizqi I, Violetta L. Abdominal and gonadal mature cystic teratomas. J Pediatr Surg Case Rep. 2022; 78, 102190. doi.org/10.1016/j.epsc.2022.102190
Huang Y, et al. Unresectable recurrence malignant sacrococcygeal teratoma in children treated with chemoradiotherapy: Case report and literature review. Rep Pract Oncol Radiother. 2019;24(4):392-398. doi: 10.1016/j.rpor.2019.06.002.