Sacrococcygeal teratoma is the most common extragonadal germ cell tumor in the pediatric population, and accounts for approximately 70% of all teratomas in childhood. A 4-to-1 female to male ratio is frequently reported.1,2 Sacrococcygeal tumors develop at the base of the spine from pluripotent stem cells, originates at the tip of the coccyx, and may contain tissues from all three germ layers. They present in two distinct phases, with the majority of cases seen in neonates with large predominately exophytic tumors, often detected in utero on prenatal sonography or at birth. A smaller cohort presents in older infants and children with primarily hidden tumors in the pelvis which have a much higher rate of malignancy.

Sacrococcygeal germ cell tumors are classified by Altman's system3 (Figure 1): Type I is primarily external (accounting for 46% in the original series); Type II, external with an intrapelvic extension (35%); Type III are visible externally, but predominately intrapelvic or abdominal (8%); and Type IV are entirely presacral and potentially with abdominal extension (10%). Altman reported that the rate of malignancy was 7% in girls and 10% in boys who were under the age of 2 months of age. In the older children (over 2 months of age), 48% of girls and 67% of boys had malignant tumors. Other studies have demonstrated that children in the older age group, particularly 1-4 years, have malignancy rates as high as 90%.4

Newborns generally present with a mass protruding from the sacral region (Type I and II) with most detected by prenatal ultrasonography. Caesarian section should be considered for lesions greater than 5 centimeters external diameter, in order to avoid dystocia and rupture. In utero procedures or resections have been performed and are generally reserved for placentomegaly, high output cardiac failure with hydrops, or polyhydramnios.5 In addition to resection, other interventions such as cyst drainage, laser ablation, or sclerosis have been reported. Of those requiring fetal intervention predominately cystic lesions have a higher survival compared with solid lesions.6, 7

While the larger exophytic tumors are obvious at birth and addressed immediately, older infants and children typically present with symptoms related to compression of the bladder or rectum with symptoms of urinary frequency or constipation. In addition, extradural spinal compression can occur leading to difficulty walking and impairment of lower extremity movement.9 These are frequently malignant yolk sac tumors with a markedly elevated alpha-fetoprotein and are usually Type III or IV Altman lesions.

Preoperative assessment of pelvic and intraabdominal extension can include ultrasonography, CT, or magnetic resonance imaging. Evaluation should define the relationship of the mass to major blood vessels including the middle sacral artery, spinal cord, and other intraabdominal/pelvic structures.9 If there is a large feeding vessel with clinical sequelae, consideration of preoperative embolization is appropriate. Radiographic evaluation with MRI is best able to fully assess neural involvement or intraspinal extension and provide a guide planning of resection and need for laminectomy.

Alpha-fetoprotein (AFP) levels should be determined on all children, serving as a sensitive marker for yolk sac malignancy. AFP levels are normally elevated in the newborn period but should return to normal by 9 months of age.8 Recent evaluation has shown the sensitivity of AFP to detect malignant recurrence at 96%.15 Almost all reported recurrences are within the first three years of life and current recommendations are for a physical examination (including rectal examination) with serum AFP levels every 3 months until 3 years of life.16 There have been some reports17 of later recurrence up to 15 years after initial resection and based on this some groups have recommended a longer follow-up period.

The Currarino triad consists of an anorectal malformation, sacral defect and a presacral mass.18 This is particularly common with anal stenosis and should prompt evaluation. Plain films may demonstrate a notched sacrum (scimitar deformity) and MRI is useful to evaluate for the presence of a mass which can include teratoma, meningocele, enteric cyst and rectal duplication. The risk of malignancy in germ cell tumors associated with Currarino Syndrome is low with most mature teratomas followed by immature teratomas19 and rarely yolk sac tumors.20 Resection of masses not involving the spine can be accomplished with a posterior sagittal anorectoplasty type approach. In addition, if the presacral mass is identified prior to correction of the anorectal malformation, the posterior sagittal anorectoplasty incision can be extended posteriorly to allow concomitant excision of the presacral mass.21

The current management of Stage I malignant (nearly all yolk sac) sacrococcygeal tumors on the current Children's Oncology Group protocol AGCT 1531 is a study question. Infants and children on study are managed with close observation without chemotherapy. Few studies have treated Stage I yolk sac tumor with observation alone, but one retrospective report of six infants, noted malignant recurrence in 2, both salvaged with chemotherapy.2 The excellent response to chemotherapy for recurrent disease as well as the ability to avoid chemotherapy for most children forms the basis of evaluating a surgery only approach for true Stage I tumors.