Sacrococcygeal teratomas / SCTs are grouped according to the amount of tumor present inside and/or outside the baby.
- Type I tumors are completely external (outside the body) and easily identified during a prenatal ultrasound or at birth.
- Type II tumors are mostly external but a portion is inside the body.
- Type III tumors are mostly internal but a portion is outside the body.
- Type IV tumors are completely inside the baby’s body and cannot be viewed externally. They are usually recognized late, and they have the highest rate of malignancy.
Most SCTs are benign (not cancerous).