Teratomas are a rare and biologically complex type of germ cell tumor (GCT) that can contain a variety of tissue types, such as hair, teeth, bone, and even neural tissue. These tumors are unique because they originate from totipotent germ cells, which have the ability to differentiate into any cell type derived from the three germ layers: ectoderm, mesoderm, and endoderm.

While most commonly arising in the gonads (ovaries or testes), teratomas can occur in extragonadal sites like the sacrococcygeal region, mediastinum, and brain. Teratomas may be benign (mature) or malignant (immature), with management strategies and prognosis varying accordingly.

This article is ideal for medical students revising for exams and patients looking to understand their diagnosis more clearly.

Pathogenesis and Cause of Teratoma

Teratomas result from aberrant differentiation of germ cells during embryonic development. These germ cells, which normally migrate to the gonadal ridge to form sperm or ova, may instead settle in ectopic locations or undergo faulty differentiation.

Key Points:

• Germ cells are totipotent, meaning they can give rise to any tissue type.
• Errors in migration or differentiation can lead to the development of a teratoma.
• This is why teratomas may include hair, skin, teeth, cartilage, muscle, or even neural tissue.

Types of Teratomas

Teratomas are classified primarily by maturity and malignancy potential.

1. Mature Teratomas

• Well-differentiated tissues
• Usually benign
• Most common type in ovarian dermoid cysts
• May recur after incomplete surgical excision
• Can be cystic, solid, or mixed

2. Immature Teratomas

• Contain poorly differentiated, embryonic tissues
• Higher risk of malignancy
• Can include somatic malignant components such as sarcoma, carcinoma, or leukemia
• Typically seen in younger females and testicular tumors

3. Special Forms

• Monodermal Teratomas (e.g., Struma Ovarii, composed predominantly of thyroid tissue)
• Teratocarcinoma (mixed with embryonal carcinoma, aggressive and malignant)

Clinical Presentation: Symptoms by Location

Symptoms depend on the location, size, and type of the teratoma. Many remain asymptomatic until they reach a size that compresses adjacent structures or cause complications like rupture or infection.

1. Sacrococcygeal Teratoma (SCT)

• Most common tumor in newborns
• Arises near the coccyx (tailbone)
• Can be external, internal, or mixed
• Symptoms may include:
  • Visible mass in the gluteal region
  • Constipation
  • Urinary retention
  • Lower limb weakness

1. Ovarian Teratoma

• Often asymptomatic unless large
• When symptomatic:
  • Lower abdominal or pelvic pain
  • Ovarian torsion → acute abdomen
  • May cause chemical peritonitis if cyst contents leak
• Rarely associated with anti-NMDA receptor encephalitis:
  • Psychiatric symptoms
  • Seizures
  • Cognitive decline

1. Testicular Teratoma

• Common in males aged 15–35
• Presents as:
  • Painless scrotal mass
  • Feeling of heaviness
• May be part of mixed germ cell tumor
• Metastasis to retroperitoneal nodes if malignant

Diagnosis of Teratoma

1. Clinical Examination

• Inspection and palpation of masses
• Assessment of neurological symptoms (especially in SCT)

2. Imaging Studies

• Ultrasound (first-line for ovarian/testicular masses)
• MRI or CT Scan (for detailed anatomic view, especially sacrococcygeal or mediastinal masses)
• Prenatal Ultrasound may detect SCT in utero

3. Tumor Markers

• Alpha-Fetoprotein (AFP): Elevated in immature/malignant teratomas
• Beta-hCG: May be raised in mixed tumors
• LDH: General tumor marker

4. Histopathology

• Definitive diagnosis via biopsy or surgical specimen
• Determines maturity and presence of malignant transformation

Treatment Approach: Based on Location and Type

General Principle:

Surgical excision is the mainstay for both benign and malignant teratomas. Chemotherapy is used in malignant or metastatic cases.

1. Sacrococcygeal Teratoma (SCT)

• In Utero:
  • Monitored via serial ultrasound
  • Large SCTs may require early delivery or fetal surgery
• Postnatally:
  • Complete surgical resection including coccyx (to prevent recurrence)
  • Chemotherapy if malignancy is present
  • Surveillance needed for 3 years due to recurrence risk

2. Ovarian Teratoma

• Mature Teratomas (Dermoid Cysts):
  • Treated via laparoscopic cystectomy
  • Risk: Rupture during surgery → chemical peritonitis
  • Oophorectomy may be necessary if large or bilateral
  • 25% of cases have bilateral cysts
• Immature Teratomas:
  • Common in girls and young women
  • Requires surgery + adjuvant chemotherapy
  • Chemotherapeutic agents: Bleomycin, Etoposide, Cisplatin (BEP)

3. Testicular Teratoma

• Radical inguinal orchiectomy is the first-line treatment
• Prepubertal teratomas are often benign
• Postpubertal teratomas are considered malignant even if histologically mature
• May need retroperitoneal lymph node dissection (RPLND)
• Chemotherapy used in case of non-teratomatous malignant elements
• Fertility preservation discussions are important prior to treatment

Prognosis

• Mature teratomas have an excellent prognosis with surgical removal
• Immature teratomas have a favorable outlook with timely chemotherapy
• SCTs, if diagnosed early and treated appropriately, have a >90% survival rate
• Testicular teratomas, if malignant, require close monitoring due to metastasis risk

Key Takeaways for Medical Students and Patients

Whether you’re a student preparing for NEET-PG or a patient trying to understand your diagnosis, knowing the biology and treatment options of teratomas can be empowering.

• Early diagnosis through imaging and tumor markers is essential.
• Histopathological analysis is critical for determining malignancy.
• Multidisciplinary care, including oncologists, surgeons, and radiologists, ensures the best outcomes.

Frequently Asked Questions: 

• What is the main cause of teratoma?

Ans. The cause of most teratomas is not completely understood. Teratomas are often associated with a number of inherited defects that affect the central nervous system, genitourinary tract, and lower spine.

• What is the most common type of teratoma?

Ans. The most common type among these tumors is mature cystic teratoma, also known as “Dermoid cyst.” Cystic teratomas constitute about 20% of ovarian germ cell tumors. The most common site of occurrence is in the ovaries and testes.

• Can a teratoma have a brain?

      Ans. These rare tumors have been known to contain hair, teeth, bone, eyes, torso tissue, hands or feet, or tissue from the brain, thyroid, liver, or lungs.