*Dept of Ob-Gyn, Division of Maternal-Fetal Medicine, Vanderbilt University, B-1100 MCN, Nashville,TN 37232-2519 Ph: 615-322-3208, Fax: 615-343-8881

Synonyms: None.

Definition: Neoplasm composed of a wide diversity of tissues from all three germ cell layers foreign to the anatomic site in which it arises. It often occurs near the coccyx, where the greatest concentration of primitive cells exists for the longest period of time.

Prevalence: Most common tumor of the newborn period, with a prevalence of 0.25-0.28:10,000 live births; M:F 1:4 ratio.

Etiology: Assumed to be derived from the pleuripotent cells of Hensen"s node located anterior to the coccyx.

Pathogenesis: It is thought that the pleuripotential cell line escapes from the control of embryonic inducers and organizers and differentiates into tissues not usually found in the sacrococcygeal region. The teratomas form and grow during intrauterine life, and can become quite large with the growth of most sacrococcygeal teratomas paralleling the growth of the fetus².

Associated anomalies: Anomalies are more frequent than in the general population: 18% in infants with sacrococcygeal teratoma compared to 2.5% in the unselected population. No particular anomaly seems to be more frequently found than others. Reported organ systems involved include the musculoskeletal, renal, CNS, cardiac, and gastrointestinal tract^3,4.

Differential diagnosis: Myelomeningoceles; also lipomas, hydromyelia, intracanalicular epidermoid tumors, dermal sinus stalks, extrarenal Wilms" tumors, retrorectal hamartomas, neuroblasto­as, and pacinomas⁵.

Prognosis: Although the majority of these tumors are histologically benign, they are associated with significant morbidity and mortality due to secondary effects of the sacrococcygeal teratoma: prematurity of the infant, dystocia and traumatic delivery, exsanguination from hemorrhage into the tumor, or high output failure secondary to a steal phenomenon. The prognosis for cure is generally good after a successful complete removal of benign sacrococcygeal teratoma².

Recurrence risk: The majority of tumors occur sporadically, but familial occurrence of presacral teratomas has been reported².

Management: Before viability, the option of pregnancy termination should be offered to the parents. If the pregnancy is continued, management is based on fetal lung maturity and the presence or absence of placentomegaly and/or hydrops fetalis. Upon fetal lung maturity without placentomegaly and/or hydrops fetalis, elective early delivery by cesarean section is indicated. Placentomegaly and/or hydrops fetalis appears to be a preterminal event and requires emergency cesarean section or possible fetal surgical intervention⁴.

MESH Sacrococcygeal teratoma BDE 0877 ICD9 2380 CDC 238.040

Introduction

Sacrococcygeal teratoma, although rare, is the most common tumor of the newborn, and has commonly been diagnosed at birth. With an increased utilization of ultrasonography, more sacrococcygeal teratomas are now discovered in utero. Prognostic differences exist when comparing fetal sacrococcygeal teratoma and neonatal sacrococcygeal teratoma. The neonatal prognosis is based on the American Academy of Pediatrics Surgical Section classification of sacrococcygeal teratoma by extension of tumor, whereas fetal prognosis appears to correlate inversely with tumor size, tumor growth rate, time of gestation at which the tumor becomes evident, and  the presence or absence of placentomegaly and/or hydrops fetalis⁶. We report 5 cases of sacrococcygeal teratoma diagnosed prenatally by ultrasound and their outcomes (Table 1).

Table 1: Outcome of five cases

Case reports

Case 1

A 29-year-old G₂P₁₀₀₁ was referred for evaluation of uterine size greater than the dates at 24 weeks gestation. The ultrasound revealed a 13x10x11 cm sacral mass consistent with sacrococcygeal teratoma (fig. 1). Amniotic fluid was slightly increased.

On a repeat ultrasound at 27 weeks gestation, the mass had grown to 18x14x14 cm with low- level venous Doppler signal within the solid component (fig. 2). Hydramnios was present. In addition, the IVC was distended and cardiomegaly was noted (fig. 1-3). There was a small pericardial effusion, but no pleural effusion or ascites. The chest diameter was decreased. The fetus appeared to be male, but the scrotum was small. The impression was cardiac failure, apparent thoracic hypoplasia, and possible genital abnormalities. On physical exam, the patient had a slight cervical change, and thus was sent home on oral terbutaline and bed rest. The patient presented at 28 weeks gestation with spontaneous rupture of membranes and premature labor. She was delivered by primary classical cesarean section secondary to the large size of the sacrococcygeal teratoma. A male was delivered with Apgars of 2 and 3. The newborn underwent an  emergency removal of the sacrococcygeal teratoma. The patient was lost to follow-up.

Figure 1: Case #1: The heterogeneous caudal mass arising from the distal spine.

Figure 2: Case #1: Doppler velocimetry revealed minimal vascularity within the sacral mass.

Figure 3: Case #1: The right-sided cavities of the heart and the inferior vena are enlarged.

Case 2

A 26-year-old G₁P₀ was referred for evaluation after an abnormal ultrasound at 12 weeks gestation. The ultrasound revealed a large homogeneous solid mass appearing to arise from the fetal sacrum (fig. 4). No other structural abnormalities were identified within the limitations of a very early gestation. The mass was felt to be consistent with sacrococcygeal teratoma. The patient elected to terminate the pregnancy, and a D&C was performed.

Figure 4: Case #2: First trimester detection of a sacral mass.

Case 3

A 19-year-old G₁P₀ underwent routine ultrasound at 17 weeks gestation, which revealed a fetus with a large, complex sacrococcygeal mass measuring 6.5x4.7 cm consistent with a sacrococcygeal teratoma (fig. 5). Venous and arterial Doppler flow was noted. The amniotic fluid was normal. The patient underwent prostin termination at 19 weeks gestation. A live female was delivered with Apgars of 1 and 1, and was transferred to the NICU for observation, where she expired shortly thereafter (fig. 6). An autopsy was performed (fig. 7). The 310g female fetus had a 7x7x3 cm soft sacrococcygeal mass with multiple fluid-filled cysts. On microscopic exam, the mass was shown to contain foci of respiratory epithelium, cartilage, gastrointestinal elements including glandular epithelium and immature liver parenchyma, and neuronal rosette formation. The tumor was benign. The fetus was also noted to have suffered an intracranial hemorrhage of the right lateral ventricle suspected to be secondary to "steal phenomenon†of  the tumor.

Figure 5:  Case #3:  Multiple echoes and cysts characteristic of a teratoma.

Figure 6: Case #3: X-ray of the fetus after delivery.

Figure 7: Case #3: The fetus at autopsy.

Case 4

A 20-year-old G₄P₃₀₀₃ was referred at 32 weeks for a sacrococcygeal teratoma detected on ultrasound. The ultrasound examination revealed a rounded cystic mass projecting from the sacral region, measuring approximately 5x7 cm (fig. 8). Mature fetal lung indices were obtained from a 36 week amniocentesis, and an elective low transverse cesarean section was performed. The patient delivered a female infant weighing 8 pounds with Apgars of 8 and 9. The infant was admitted to the NICU for observation and underwent resection of the sacrococcygeal teratoma. A 6x8 cm cystic pedunculated mass was removed en bloc with the coccyx. Good cosmetic results with no complications were achieved.

Figure 8: Case #4: Longitudinal view of sacrococcygeal mass.

Case 5

A 26-year-old G₂P₁, who underwent an ultrasound at 20 weeks gestation suggestive of a 6 cm sacral mass with normal cranial and vertebral findings, was referred for further evaluation (fig. 9-10). Repeat sonography demonstrated a large 10 cm heterogeneous sacrococcygeal teratoma. Doppler flow studies indicated minimal blood supply and an abnormal umbilical artery S/D ratio of 5.14. The inferior vena cava and heart were enlarged. The patient proceeded with the pregnancy and underwent elective low-vertical cesarean section at 35 weeks. A male weighing 3105g with Apgars of 8 and 9 was admitted to the NICU. The infant"s complex pedunculated tumor arising from the coccyx and the right buttock was resected the next day (fig. 11-12). The gluteal muscles were distorted and the tumor was adherent to the ischium. Branches of the sciatic nerve were sacrificed to achieve a complete resection.

Figure 9: Case #5:  Longitudinal and caudal views of complex sacral

Figure 10: Case #5: Longitudinal view of lumbosacral spine reveals an intact neural tube, differentiating the teratoma from a complicated meningomyclocele.

Figure 11: Case #5: Caudal view at delivery.

Figure 12: Case #5: The complexity of the teratoma is appreciated

prior to surgical resection.  The primary mass originated from the

Discussion

Definition

Sacrococcygeal teratoma is a congenital germ cell tumor arising in the presacral areas, and is the most common tumor of the newborn period. This usually benign tumor is composed of a wide diversity of tissue foreign to the sacrum and contains all three germ cell layers. Neuroglias are the most common histologic finding in sacrococcygeal teratoma⁷. The tumors are subdivided and classified according to their location:

• Type I - tumors predominantly external with only minimal presacral involvement;

• Type II - tumors presenting externally but with a significant intrapelvic extension;

• Type III - tumors apparent externally but with predominant pelvic mass and extending into abdomen;

• Type IV - Presacral with no external presentation³.

Pathogenesis

Sacrococcygeal teratomas arise from the primitive knot or Hensen"s node. Hensen"s node is an aggregation of totipotential cells that are the primary organizers of embryonic development. Originally located in the posterior portion of the embryo, it migrates caudally during the first weeks of life inside the tail of the embryo, finally resting anterior to the coccyx. Segregation of totipotential cells from Hensen"s node probably gives rise to sacrococcygeal teratomas⁸. These pleuripotential cells escape from the control of embryonic inducers and organizers and differentiate into tissues not usually found in the sacrococcygeal region². The tumor occurs near the coccyx, where the greatest concentration of primitive cells exists for the longest period of time during development.

Prenatal diagnosis

The most common prenatal presentation of sacrococcygeal teratoma is uterus size greater than dates⁵.  However, the majority of cases usually manifest no clinical symptoms during pregnancy, and with the increasing frequency of routine ultrasound during pregnancy, more incidental findings of these tumors will occur. The differential diagnosis of sacrococcygeal teratomas include myelo-meningoceles, lipomas, hydromyelia, intracanalicular epidermoid tumors, dermal sinus stalks, extrarenal Wilms" tumors, retrorectal hamartomas, neuro­bla­stomas, and pacinomas⁴. Excluding meningo­mye­lo­cele and twin fetuses, a mass attached to the fetal rump is most likely a teratoma⁶. A sacrococcygeal teratoma can be distinguished from its primary differential meningo­myelocele by its more abundant internal soft tissue, whereas the meningocele is more completely cystic in nature⁹. alpha-Fetoprotein can be normal or elevated in sacrococcygeal teratomas but sono­graphy can distinguish these lesions from neural tube defects¹⁰. Early prenatal sonographic detection of sacrococcygeal teratoma allows for optimal perinatal obstetric and surgical management.

Management and prognosis

Neonatal sacrococcygeal teratoma is a well-defined entity. The natural history of fetal sacrococcygeal teratoma is not so well defined, and although the American Academy of Pediatrics Surgical Section clinical classification is an important prognostic indicator in neonatal sacrococcygeal teratoma, it does not appear to predict outcomes in fetal sacrococcygeal teratoma¹¹. If the diagnosis of sacrococcygeal teratoma is made early enough in gestation and if any poor prognostic factors such as oligohydramnios, severe renal anomalies, or marked hydrops are present, elective termination of pregnancy may be considered for sacrococcygeal teratoma². Most fetal teratomas can be managed by planned delivery and postnatal surgery. Holzgreve et al have described an algorithm to approach the management of sacrococcygeal teratoma based on fetal lung maturity and the presence or absence of placentomegaly and/or hydrops fetalis (Table 2 )⁵. In the absence of placentomegaly and hydrops, the fetus should be followed by serial ultrasound until fetal pulmonary maturity is adequate for survival. The patient should then undergo elective early delivery by cesarean section to avoid trauma to the mass or dystocia.

The occurrence of placentomegaly and/or hydrops fetalis appears to be a preterminal event indicating imminent fetal demise. Its occurrence in a fetus with adequate pulmonary maturity demands emergency cesarean section. Fetuses developing placentomegaly and/or fetal hydrops prior to adequate lung maturity are the most difficult management decisions. These fetuses may be candidates for transfusion or fetal surgical intervention⁵.

It is important to predict early after diagnosis which fetuses will survive and which will develop hydrops and die. Measurement of fetal aortic blood flow and cardiac output with a Doppler probe may be used to follow the development of high-output cardiac failure before the appearance of fetal hydrops and might potentially be used to predict outcome¹².

Prognosis of sacrococcygeal teratoma is improving due to prenatal detection, planned intrapartum management, and prompt surgical resection¹³. The optimal outcome for fetal sacrococcygeal teratoma requires better understanding of its unique natural history and the perfection of monitoring and fetal intervention.

Table 2: Management of fetuses with sacrococcygeal teratoma ⁵

Acknowledgement

The authors would like to express their gratitude to Philippe Jeanty, MD, PhD for providing cases 1-4.

References

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