Sacrococcygeal teratoma natural history, complications, and prognosis

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Overview
Sacrococcygeal teratoma (SCT) is a teratoma (a kind of tumor) located at the base of the coccyx (tailbone). It is thought to be a derivative of the primitive streak.

Natural history
SCT is seen in 1 in every 35,000 live births, and is the most common tumor presenting in newborn humans. Most SCTs are found in babies and children, but SCTs have been reported in adults and the increasingly routine use of prenatal ultrasound exams has dramatically increased the number of diagnosed SCTs presenting in fetuses. Like other teratomas, an SCT can grow very large. Unlike other teratomas, an SCT sometimes grows larger than the rest of the fetus.

Sacrococcygeal teratomas are the most common type of germ cell tumors (both benign and malignant) diagnosed in neonates, infants, and children younger than 4 years. SCTs occur more often in girls than in boys; ratios of 3:1 to 4:1 have been reported.

Historically, sacrococcygeal teratomas present in 2 clinical patterns related to the child’s age, tumor location, and likelihood of tumor malignancy. With the advent of routine prenatal ultrasound examinations, a third clinical pattern is emerging.


 * Fetal tumors present during prenatal ultrasound exams, with or without maternal symptoms. SCTs found during routine exams tend to be small and partly or entirely external.  The internal SCTs are not easily seen via ultrasound, unless they are large enough to reveal their presence by the abnomal position of the fetal urinary bladder and other organs, but large fetal SCTs frequenty produce maternal complications which necessitate non-routine, investigative ultrasounds.


 * Neonatal tumors present at birth protruding from the sacral site and are usually mature or immature teratomas.


 * Among infants and young children, the tumor presents as a palpable mass in the sacropelvic region compressing the bladder or rectum. These pelvic tumors have a greater likelihood of being malignant. An early survey found that the rate of tumor malignancy was 48% for girls and 67% for boys older than 2 months at the time of sacrococcygeal tumor diagnosis, compared with a malignant tumor incidence of 7% for girls and 10% for boys younger than 2 months at the time of diagnosis. The pelvic site of the primary tumor has been reported to be an adverse prognostic factor, most likely caused by a higher rate of incomplete resection.


 * In older children and adults, the tumor may be mistaken for a pilonidal sinus, or it may be found during a rectal exam or other evaluation.

Complications
Maternal complications of pregnancy may include mirror syndrome. Maternal complications of delivery may include a Cesarean section or, alternatively, a vaginal delivery with mechanical dystocia.

Complications of the mass effect of a teratoma in general are addressed on the teratoma page. Complications of the mass effect of a large SCT may include hip dysplasia, bowel obstruction, urinary obstruction, hydronephrosis and hydrops fetalis. Even a small SCT can produce complications of mass effect, if it is presacral (Altman Type IV). In the fetus, severe hydronephrosis may contribute to inadequate lung development. Also in the fetus and newborn, the anus may be imperforate.

Later complications of the mass effect and/or surgery may include neurogenic bladder, other forms of urinary incontinence, fecal incontinence, and other chronic problems resulting from accidental damage to or sacrifice of nerves and muscles within the pelvis. Removal of the coccyx may include additional complications. In one review of 25 patients, however, the most frequent complication was an unsatisfactory appearance of the surgical scar.

Late effects
Pelvic scarring may necessitate that pregnant women who are SCT survivors deliver their babies by [Cesarean section].

Complications of not removing the coccyx may include both recurrence of the teratoma and metastatic cancer. Late malignancies usually involve incomplete excision of the coccyx and are adenocarcinoma.