Sacrococcygeal teratomas (SCTs) arise from a totipotent stem cell in Henson’s node.
Most SCTs are large, complex, solid, and cystic masses but may have intrapelvic or intra-abdominal extension.
Ultrasound alone will make the diagnosis, but fetal MRI will help define anatomic relations, and echocardiographs will evaluate high-output state.
SCTs that are >10 cm, solid, highly vascular, or rapidly growing are at highest riskfor hydrops.
Fetal surgery may be an option in cases that develop early signs of hydrops.
Cesarean section is usually indicated for large SCTs due to risk of rupture and exsanguination.
SCTs are usually benign but can have immature elements or rests of malignant yolk sac tumor.
Close serial follow-up for at least 3 months for tumor recurrence is indicated with serial α-fetoprotein levels, physical exam, and imaging studies.
Sacrococcygeal teratoma (SCT) is defined as a neoplasm composed oftissues from either all three germ layers or multiple foreign tissues lacking an organ specificity arising in the sacrococcygeal region (Gross et al., 1951; Mahour et al., 1975). Because of the multiple cell lineages that characterize these tumors, it was previously suggested that SCT was of germ cell origin or a form of fetus in fetu (Theiss et al., 1960; Linder et al., 1975). Early theories suggested a “twinning accident” with incomplete separation during embryogenesis and abnormal development of one fetus (Waldhausen et al., 1963; Ashley, 1973; Cousins et al., 1980). In support of this theory, several authors have noted a family history of twinning in many SCT patients (Hickey and Layton, 1954; Grosfeld et al., 1976; Gross et al., 1987). However, more recently, SCT has been thought to arise from a totipotent somatic cell originating in Hensen’s node (Gross et al., 1987). This node is a caudal cell mass in the embryo that appears to escape normal inductive influences (Bale, 1984). Others hypothesize that SCT is derived from totipotent cells in reproductive gland anlage (Abbott et al., 1966).
SCT has been classified by the relative amounts of presacral and external tumor present [American Academy of Pediatrics Surgery Section (AAPSS) Classification (Table 115-1 and Figure 115-1)] (Altman et al., 1974). The utility of this classification scheme lies in the relationship between stage and timing of diagnosis, ease of resection, and malignant potential. Type I SCT is evident at birth, is usually easily resected, and has a low malignant potential. Similarly, types II and III SCT are recognized at birth, but resection may be difficult, requiring both an anterior and a posterior approach. In type IV SCT, the diagnosis may be delayed until it becomes symptomatic at a later age. Malignant transformation has frequently occurred by the time a type IV SCT is diagnosed.
Table 115-1AAPSS Staging Classification of Sacrococcygeal Teratomas ||Download (.pdf) Table 115-1 AAPSS Staging Classification of Sacrococcygeal Teratomas
|Type ||Description |
|I ||Completely external; no presacral component |
|II ||External component and internal pelvic component |
|III ||External component and internal component extending into abdomen |
|IV ||Completely internal and no external component |
AAPSS classification of the different types of sacrococcygeal teratoma, based on the location of the tumor. (Reprinted, with permission, from Holzgreve W, Flake AW, Langer JC. The fetus with sacrococcygeal teratoma. In: Harrison MR, Golbus MS, Filly RA, eds. The Unborn Patient. Philadelphia: WB Saunders; 1991:461).
SCT is one of the most common tumors in newborns; however, it is still rare, occurring in 1 in 23,000 to 1 in 40,000 livebirths (Schiffer and Greenberg, 1956; Altman et al., 1974; Tapper and Lack, 1983; Forrester and Merz, 2006). Females are four times more likely to be affected as males, however, malignant change is more frequently observed in males (Abbott et al., 1966; Conklin and Abell, 1967; Carney et al., 1972; Fraumeni et al., 1973; Altman et al., 1974).
Retrospective prenatal diagnosis of SCT was first made in the mid-1970s, and the first prospective prenatal diagnosis was reported by Horger and McCarter in 1979. They described a 13-cm complex mass at the caudal end of the fetus, with solid and cystic areas and bizarre internal echoes associated with polyhydramnios. This typical prenatal sonographic appearance has been confirmed by other authors (Figure 115-2) and approximately 60 cases of prenatally diagnosed SCT have been reported (Seeds et al., 1982; Grisoni et al., 1988; Bond et al., 1990). The most common clinical presentation is uterine size greater than dates, initiating an ultrasound examination (Seeds et al., 1982). To date, the earliest diagnosis of SCT that has been made is 12 3/7 weeks of gestation (Roman et al., 2004).
Prenatal sonographic image demonstrating large type II sacrococcygeal tumor in a 23-week-old fetus. In this view, the intrapelvic extent of the tumor cannot be seen.
SCTs can grow at an unpredictable rate to tremendous dimensions. Several case reports note fetal tumors as large as 25 by 20 cm (Heys et al., 1967; Weiss et al., 1976). These tumors are generally exophytic (AAPSS type I), but may extend retroperitoneally displacing pelvic (type II) or abdominal structures (type III) (Litwiller, 1969).
Most SCTs are solid or mixed solid and cystic, consisting of randomly arranged irregularly shaped cysts (Seeds et al., 1982; Chervenak et al., 1985). Purely cystic SCT has also been described prenatally (Seeds et al., 1982; Hogge et al., 1987). Calcifications can be seen microscopically, although the majority are not visible on prenatal ultrasound examination. Most prenatally diagnosed SCTs are extremely vascular, which is easily demonstrated with the use of color flow Doppler studies (Figure 115-3). Three-dimensional power Doppler has been suggested to demonstrate the large vascular volume in SCT (Sciaky-Tamir et al., 2006). Polyhydramnios has been noted in most cases of prenatally diagnosed SCT, and–although the mechanisms for this are not known–it is likely secondary to renal hyperfiltration occurring as a result of high-output state (Chervenak et al., 1985).
Color flow Doppler study of the same fetus shown in Figure 115-1 demonstrating the vascularity of the tumor.
Hepatomegaly, placentomegaly, and nonimmune hydrops have also been seen in association with SCT and appear to be secondary to high-output cardiac failure (Heys et al., 1967; Cousins et al., 1980; Gergely et al., 1980; Kapoor and Saha, 1989; Bond et al., 1990; Flake, 1993; Hedrick et al., 2004). High-output failure may be due to tumor hemorrhage or arteriovenous shunting within the tumor (Cousins et al., 1980; Flake et al., 1986; Alter et al., 1988; Schmidt et al., 1989; Bond et al., 1990). Some authors have attributed heart failure with subsequent hydrops to severe fetal anemia secondary to tumor hemorrhage (Alter et al., 1988). However, normal fetal hematocrits have also been reported, suggesting that congestive heart failure is more often due to high-output cardiac failure from arteriovenous shunting within the tumor (Schmidt et al., 1989). The demonstration ofheart failure or hydrops on ultrasound examination is usually a preterminal event (Flake et al., 1986; Kuhlmann et al., 1987; Bond et al., 1990).
Controversy exists regarding the presence of associated anomalies and the need for chromosome analysis. The incidence of coexisting anomalies is 11% to 38%, primarily involving the nervous, cardiac, gastrointestinal, genitourinary, and musculoskeletal systems (Hickey and Layton, 1954; Schiffer and Greenberg, 1956; Carney et al., 1972; Fraumeni et al., 1973; Altman et al., 1974; Izant and Filston, 1975; Gonzalez-Crussi et al., 1978; Ein et al., 1980; Holzgreve et al., 1985; Kuhlmann et al., 1987; Werb et al., 1992). Several authors postulate that at least some of these anomalies are related to tumor development. Others have reported an increased incidence of spinal deformities (Ewing, 1940; Gruenwald, 1941; Alexander and Stevenson, 1946; Bentley and Smith, 1960; Wilson et al., 1963; Carney et al., 1972). Most authors agree with Berry et al.’s (1970) observation that local abnormalities such as rectovaginal fistula and imperforate anus are thought to be directly related to tumor growth during fetal development. Aneuploidy has not been reported with SCT and we do not recommend amniocentesis for karyotype analysis unless there are multiple anomalies, advanced maternal age, or fetal surgery is contemplated.
Fetal MRI has emerged as an adjunctive imaging modality that can provide important anatomical detail in cases of SCT (Avni et al., 2002; Hedrick et al., 2004; Nassenstein et al., 2006). MRI may be particularly useful in defining the pelvic component of SCT and impact on other pelvic structures (Garel et al., 2005). In cases in which fetal surgery is being considered, fetal MRI provides a broader field of view than ultrasound and may be helpful in operative planning. In cases in which SCT has a pelvic component or there is polyhydramnios, oligohydramnios, hydronephrosis or hydrocolpos, fetal MRI may provide additional information on the anatomical relationships not apparent on ultrasound alone (Danzer et al., 2006). Fetal MRI in cases of cystic SCT may be particularly helpful in excluding myelomeningocele from the differential diagnosis (Yoon and Park, 2005; Danzer et al., 2006).
The differential diagnosis of SCT includes lumbosacral myelomeningocele, which invariably demonstrates a spinal defect. Myelomeningoceles have a cystic or semicystic rather than a solid appearance and do not contain calcifications. Examination of the fetal brain is helpful in establishing the diagnosis, as most fetuses with lumbosacral myelomeningocele will have associated cranial findings. Rarer entities that mimic SCT include neuroblastoma, glioma, hemangioma, neurofibroma, cordoma, leiomyoma, lipoma, melanoma, and any of 50 tumors or malformations reported in the sacrococcygeal region (Table 115-2) (Lemire and Beckwith, 1982; Sebire et al., 2004; Tanaka et al., 2005).
Table 115-2Tumors and Malformations of the Sacrococcygeal Region* ||Download (.pdf) Table 115-2 Tumors and Malformations of the Sacrococcygeal Region*
|Subcutaneous lipoma Teratoma |
|Endodermal sinus tumor |
|Myxopapillary ependymoma |
|Giant cell tumor ofsacrum |
|Wilms’ tumor in teratoma |
|Glomus tumor |
|Lumbosacral lipoma |
|Tail appendage |
|Teratoma in meningomyelocele |
Biochemical markers such as α-fetoprotein (AFP) and acetylcholinesterase are not reliable in distinguishing SCTs from other abnormalities (Holzgreve et al., 1987). It has been suggested, however, that AFP can be used to differentiate benign from malignant tumors, as marked elevations of AFP may reflect the presence of a malignant endodermal sinus component to the tumor (Tsuchilda et al., 1975; Grosfeld et al., 1976; Gonzalez-Crussi et al., 1978; Gonzalez-Crussi, 1982). AFP levels can be extremely high in normal newborns, limiting the utility of this marker to distinguish benign from malignant lesions (Ohama et al., 1997).
ANTENATAL NATURAL HISTORY
The antenatal natural history of prenatally detected SCT is not as favorable as that of SCT presenting at birth. Well-defined prognostic factors for SCT diagnosed postnatally, as outlined in the AAPSS classification system, do not necessarily apply to fetal cases (Altman et al., 1974; Bond et al., 1990) (see Table 115-1). While the mortality rate for SCT diagnosed in the newborn is at most 5%, the mortality rate for fetal SCT approaches 50% (Flake et al., 1986; Bond et al., 1990; Flake, 1993; Hedrick et al.,2004).
Most SCTs are histologically benign. The incidence of malignant elements present in fetal SCT has ranged from 7% to 30% (Hedrick et al., 2004; Heerema-McKenny et al., 2005). Malignancy appears to be more common in males, especially with solid versus complex or cystic tumors (Schey et al., 1977). The presence of histologically immature tissue does not necessarily signify malignancy (Carney et al., 1972; Gonzalez-Crussi, 1982). Calcifications occur more often in benign tumors but may also be seen in malignant tumors and are unreliable indicators of malignant potential (Hickey and Layton, 1954; Waldhausen et al., 1963; Grosfeld et al., 1976; Schey et al., 1977; Horger and McCarter, 1979). Although there is one reported case of malignant yolk sac differentiation in a fetal SCT, there has not been a case ofmetastatic teratoma in a neonate with a prenatally diagnosed SCT (Holzgreve et al., 1985; Flake, 1993).
The prenatal history of SCT is quite different from the postnatal natural history. Flake et al. (1986) reviewed 27 cases of prenatally diagnosed SCT. Five cases were electively terminated and 15 of the remaining 22 died, either in utero or shortly after delivery. The majority of these patients presented between 22 and 34 weeks of gestation with a uterus large for gestational age secondary to severe polyhydramnios. The presence of hydrops and/or polyhydramnios was associated with intrauterine fetal death in seven of seven cases. The International Fetal Medicine and Surgery Society reported a mortality rate of 52% among cases of prenatally diagnosed SCT (Bond et al., 1990). When SCT was seen in association with placentomegaly or hydrops, all affected fetuses died in utero. The indication for ultrasound examination was also found to be a predictive factor. If SCT was an incidental finding, the prognosis was favorable at any gestational age. However, if the ultrasound examination was performed for maternal indications, 22 of 32 fetuses died. In addition, diagnosis prior to 30 weeks was associated with a poor outcome.
Sheth et al. (1988) also reported significant perinatal mortality associated with SCT, with only 6 survivors among 15 cases diagnosed prenatally. Three off our cases associated with hydrops were rapidly fatal. The sole survivor was salvaged by emergency cesarean section at 35 weeks. This series was unusual because three cases had severe obstructive uropathy and secondary renal dysplasia. A more favorable outcome was reported by Gross et al. (1987) in which 8 of 10 fetuses with prenatally diagnosed SCT survived. However, no fetus had hydrops or placentomegaly, and the two nonsurvivors were electively terminated.
Hydrops in SCT is usually, but not always, fatal. Nakoyama et al. (1991) reported survival in two fetuses with SCT presenting with hydrops at 27 and 30 weeks of gestation. In addition, Robertson et al. (1995) were able to salvage a hydropic fetus at 26 weeks of gestation by staged resection of the SCT in the neonatal period (Figure 115-4). In this case, acute rapid growth of the SCT led to polyhydramnios and preterm delivery. After delivery, the newborn was noted to be in a high-output state from shunting through the tumor. In a staged resection, the tumor was initially devascularized by ligation of both internal iliac arteries. Twenty-four hours later, the external portion of the mass was resected. The infant subsequently underwent resection of the intrapelvic portion of the tumor at 3 months of age, and did well.
Postnatal photograph of a 26-week-gestation premature newborn with a large SCT. A. The SCT has distorted the perineum so that the anus is in a plane anterior to the genitalia. The tip of the clamp is in the anal orifice. B. The same tumor following devascularization.
Hedrick et al. (2004) reviewed their experiences with 30 cases of prenatally diagnosed SCT and reported 4 terminations, 5 fetal deaths, 7 neonatal deaths, and only 14 survivors (47%). Among the 26 patients continuing the pregnancy, 81% experienced obstetric complications including polyhydramnios (n = 7), oligohydramnios (n = 4), preterm labor (n = 13), pre-eclampsia (n = 4), gestational diabetes (n = 1), HELLP syndrome (n = 1), and hyperemesis (n = 1).
Sonographic features of SCT such as size, AAPSS classification, solid or cystic composition, or presence or absence of calcifications have not been predictive of either fetal survival or future malignant potential (Altman et al., 1974; Flake, 1993). One exception to this may be the unilocular cystic form of SCT, which has a relatively favorable prognosis because of benign histology and limited vascular and metabolic demand (Horger and McCarter, 1979; Mintz et al., 1983). The growth of the SCT in relation to the size of the fetus is also unpredictable and may increase, decrease, or stabilize as gestation proceeds. However, a rapid phase of tumor growth usually precedes the development of placentomegaly and hydrops.
Highly vascular lesions are more likely to undergo rapid tumor growth and to be associated with the development of placentomegaly and hydrops. The prenatal mortality, unlike postnatal mortality, is not due to malignant degeneration, but to complications of tumor mass or tumor physiology (Flake et al., 1993). The tumor mass may result in malpresentation or dystocia, which in turn may result in tumor rupture and hemorrhage during delivery. Dystocia has been reported in 6% to 13% of cases in postnatal series (Giugiaro et al., 1977; Musci et al., 1983; Gross et al., 1987). SCTs may also spontaneously rupture in utero leading to significant fetal anemia or death (Sy et al., 2006). The most important benefit of prenatal diagnosis is prevention of dystocia by elective or emergency cesarean section. Tumor mass effect may also result in uterine instability and preterm delivery because of uterine distention (Flake et al., 1986; Bond et al., 1990). Massive polyhydramnios is frequently seen in large fetal SCT, which also predisposes to uterine irritability and preterm delivery.
SCT may occur in twins further complicating the prenatal management. In Hedrick et al.’s series, 10% of the cases occurred in twin gestations (Hedrick et al., 2004). The presence of SCT in a twin gestation increases the risk of preterm delivery. Because SCT is associated with an increased risk of fetal death, intrauterine demise of a monochorionic twin with SCT places the surviving unaffected co-twin at risk of adverse neurologic outcome (Ayzen et al., 2006).
The physiologic consequence of fetal SCT depends on the metabolic demands of the tumor, blood flow to the tumor, and the presence and degree of anemia. The features of the SCT–whether cystic or solid, size, and rate of growth–all affect the metabolic demands of fetal SCT. While classically thought to derive its blood supply from the middle sacral artery (Smith et al., 1961), these large tumors often parasitize blood supply from the internal and external iliac systems. This may result in vascular “steal” from the umbilical artery blood flow to the placenta. As an SCT outgrows its blood supply, tumor necrosis may occur leading to tumor rupture and hemorrhage. The high-output cardiac failure in fetal SCT can be diagnosed by fetal echocardiography and Doppler study (Flake et al., 1986; Langer et al., 1989; Schmidt et al., 1989). When hydrops develops in fetuses with SCT, all have dilated ventricles and dilated inferior venae cavae due to increased venous return from the lower body (Flake, 1993). Serial sonographic examinations in fetal SCT often show progressive increases in combined ventricular output and descending aortic flow velocity. In general, placental blood flow is decreased by the vascular steal by the SCT (Schmidt et al., 1989; Flake, 1993) and may lead to the finding of end-diastolic flow reversals in the umbilical artery.
Benachi et al. (2006) have suggested a prenatal prognostic classification system based on tumor diameter, vascularity, and rapidity of growth. In a group of 44 fetal SCTs divided into group A (tumor < 10 cm, absent or mild vascularity and slow growth), group B (tumor >10 cm, pronounced vascularity or high output cardiac failure and rapid growth), and group C (tumor >10 cm, predominantly cystic lesion with absent or mild vascularity and slow growth). Groups A and C did well with gestational age at delivery of 38 and 37 weeks, respectively while group B delivered prematurely at 31 weeks of gestation. There was no mortality in either group A or C but was 52% for group B. The newborns in group B also have a much longer length of stay postnatally (Benachi et al. 2006). Postnatal measurements of umbilical arterial blood gases before and after removal of a large SCT demonstrate that the tumor acts as a large arteriovenous shunt.
Although the primary cause ofdeath in neonatal SCT is malignant invasion, in prenatal SCT the complications of prematurity or exsanguinating tumor hemorrhage at delivery predominate (Flake et al., 1986; Bond et al., 1990; Adzick and Harrison, 1994). Weekly sonographic examinations shouldbe performed during pregnancy to assess amniotic fluid index, tumor growth, fetal well-being, and early evidence of hydrops (Chervenak et al., 1985; Langer et al., 1989). Serial Doppler echocardiographic evaluations should be performed in all patients to detect early signs of high-output state, as evaluated by an increased diameter of the inferior vena cava (should be >1 cm), increased descending aortic flow velocity (>120 cm/s) (Alter et al., 1988; Flake, 1993; Bahlmann et al., 2001), or increased combined ventricular output (> 500 mL/kg/min for CVO) (Bahlmann et al., 2001). Evidence of the earliest signs of heart failure, placentomegaly, and/or hydrops should be sought, as these may progress rapidly and are harbingers of preterminal events (Langer et al., 1989). Bond et al. (1990) reported a uniformly fatal outcome when SCT was associated with placentomegaly and/or hydrops. Flake et al. (1986) reported seven of seven fetal deaths in pregnancies complicated by placentomegaly and hydrops.
Weekly amniocenteses to determine pulmonary maturity are recommended by some physicians after 36 weeks of gestation, with delivery once fetal lung maturity is established (Adzick and Harrison, 1994). Many pregnancies complicated by SCT do not reach this gestational age however. Warning signs and symptoms of preterm labor should be stressed at prenatal visits, and limitation of activity, treatment, and cervical checks may be indicated (Garmel et al., 1994).
The recommended mode of delivery is determined by the size of the tumor. Vaginal delivery may be possible with some small tumors (Grisoni et al., 1988; Flake, 1993). Complications of vaginal delivery, however, have included fetal death after rupture, avulsion, or asphyxia (Schiffer and Greenberg, 1956; Heys et al., 1967; Grosfeld et al., 1976; Giugiaro et al., 1977; Chervenak et al., 1985; Holzgreve et al., 1987; Werb et al., 1992). Cesarean delivery is recommended to avoid trauma-induced hemorrhage or dystocia, especially in large (> 5–10 cm) tumors (Chervenak et al., 1985; Gross et al., 1987; Hogge et al., 1987; El-Qarmalaui et al., 1990; Flake, 1993). The size of the tumor may also influence the type of uterine incision. A large tumor may warrant a classical uterine incision, especially in a preterm infant (Chervenak et al., 1985).
Dystocia has been reported when the diagnosis of SCT was unsuspected in as many as 6% to 13% of cases (Hickey and Layton, 1954; Schiffer and Greenberg, 1956; Seidenberg and Hurwitt, 1958; Lowenstein et al., 1963; Hickey and Martin, 1964; Abbott et al., 1966; Lu and Lee, 1966; Heys et al., 1967; Desai, 1968; Kowalski and Sokolowska-Pituchowa, 1968; Werner and Swiecicka, 1968; Litwiller, 1969; Weiss et al., 1976; Seeds et al., 1982; Tanaree, 1982; Edwards, 1983; Mintz et al., 1983; Musci et al., 1983; Varga et al., 1987; El-Shafie et al., 1988; Johnson et al., 1988). Transabdominal and transvaginal aspirations of large cysts have been attempted with variable results to facilitate delivery in the face of significant dystocia (Abbott et al., 1966; Desai, 1968; Litwiller, 1969; Weiss et al., 1976; Tanaree, 1982; Edwards, 1983; Mintz et al., 1983; Musci et al., 1983; El-Shafie et al., 1988; Johnson et al., 1988). Cyst decompression has also been used to treat maternal discomfort, and in one case cyst amniotic shunting was used to treat bladder outlet obstruction due to tumor compression (Garcia et al., 1998; Kay et al., 1999; Jouannic et al., 2001). It is hoped that prenatal detection of SCT will prevent such unforeseen emergencies (Musci et al., 1983).
Fetal SCT is sometimes associated with maternal complications. The mother should be observed for signs and symptoms of preeclampsia, such as the “mirror syndrome” described by Nicolay et al. in association with SCT and hydrops (Nicolay and Gainey, 1964; Cousins et al., 1980; Flake et al., 1986; Coleman et al., 1987; Langer et al., 1989; Bond et al., 1990). Delivery should be performed in a tertiary care center, with neonatologists and pediatric surgeons available.
The uniformly dismal outcome in fetuses with SCT complicated by placentomegaly and hydrops has been the impetus for resection of this tumor in utero. Harrison was the first to attempt antenatal resection of an SCT (Langer et al., 1989). In this first case, a fetus was noted to be markedly hydropic with a significantly elevated combined ventricular output (972 mL per kilogram of body weight per minute) at 24 weeks (Langer et al., 1989; Flake, 1993). In addition, the mother had mild hypertension, edema, and proteinuria. Preterm labor developed that was controlled with tocolytic agents. At surgery, the exophytic portion of the tumor was dissected free of the anus and rectum and amputated at its base with a stapling device. Despite the resection, the fetus remained hydropic, with an elevated combined ventricular output of 869 mL per kilogram of body weight per minute. Percutaneous umbilical cord blood sampling showed the fetal hematocrit to be only 16%. This was increased to 27% by blood transfusion. The fetus subsequently improved significantly, with sonographic resolution of hydrops, and a decrease in descending aortic flow to 524 mL/kg of body weight per minute. However, the maternal mirror syndrome progressed to pulmonary edema and on postoperative day 12 a 26-week-gestation fetus was delivered by cesarean section and died of pulmonary immaturity at 6 hours of age. The mother’s illness resolved within 2 days. Autopsy showed no evidence of hydrops and no residual tumor.
A second case was attempted at 26 weeks of gestation, when dramatic enlargement of the tumor resulted in early hydrops, elevated combined ventricular output, and severe polyhydramnios (Flake, 1993). The surgery went uneventfully, and the base of the tumor was stapled to excise the exophytic portion and reverse the hyperdynamic state. The fetus did well until postoperative day 8, when irreversible preterm labor developed and the fetus was delivered by emergency cesarean section. Because the histology of the resected specimen was interpreted as an immature teratoma grade III/III, with predominance of neuroepithelial elements and foci of yolk sac differentiation, resection of residual tumor was attempted on the 13th day of postnatal life. During dissection of the presacral space the baby experienced complete cardiovascular collapse due to a paradoxical air embolism. The histology of the tumor revealed grade III/III immature teratoma, but the residual tumor was more mature than the previous tumor specimen and contained no foci of yolk sac differentiation.
The first successful resection of fetal SCT with long-term survival was reported by Adzick et al. (1997). At 25 weeks of gestation a type II SCT had rapid enlargement and development of polyhydramnios and placentomegaly, with associated maternal tachycardia and proteinuria suggesting impending maternal mirror syndrome (Figure 115-5). At surgery, the exophytic portion of the tumor was dissected free of the anus and rectum and the base of the tumor excised with a thick tissue stapling device (Figure 115-6). The mother and fetus did well postoperatively, with resolution of hydrops and placentomegaly within 10 days. Pathology of the tumor showed grade III/III immature teratoma without evidence of yolk sac differentiation. At 29 weeks of gestation preterm labor prompted cesarean delivery. Postnatally, the female infant underwent resection of the coccyx and surrounding tissue at 2 months of age, but no residual tumor was found. She did well until 1 year of age when AFP levels became elevated to 22,000 ng/mL and she presented with pleural effusions, lung nodules, and a recurrent buttock mass from a metastatic yolk sac tumor. She has had an excellent response to chemotherapy. Hedrick et al. subsequently reported their experience with four open fetal surgeries for SCT with all four surviving the procedure to delivery at an average gestational age of 29 weeks (range 27.6–31.7 weeks). There was one neonatal death due to premature closure of the ductus arteriosus thought to be secondary to indomethacin exposure as a tocolytic following fetal surgery. Other complications experienced in these fetal surgery patients included embolism resulting in renal infarction and multiple jejunal atresias (n = 1), chronic lung disease (n = 1), and development of metastatic endodermal yolk sac tumor (n = 1) (Hedrick et al., 2004).
Fetal magnetic resonance imaging scan demonstrating in coronal (left) and sagittal (right) sections a fetus at 25 weeks of gestation with type II SCT. The large intrapelvic portion of tumor has completely blocked the bladder outlet, causing megacystis. The fetal urine is detectable by the presence of contrast dye. (Reprinted, with permission, from Quinn TM, Hubbard AM, Adzick NS. Prenatal magnetic resonance imaging enhances fetal diagnosis. J Pediatr Surg. 1998;33:553-558.)
Intraoperative view of a 25-week-gestation fetus undergoing resection in utero. A. The ruptured tumor and lower extremities of the fetus are delivered from the wound. B.The fetal buttock wound is closed immediately following resection. (Reprinted, with permission, from Adzick NS, Crombleholme TM, Morgan MA, Quinn TM. A rapidly growing fetal teratoma. Lancet. 1997;349:538.)
While clinical experience remains limited, there have been other cases of SCT successfully resected in utero at the University of California, San Francisco and at Cincinnati Children’s Hospital. For the fetus with a large SCT associated with early signs of hydrops or placentomegaly, resection in utero remains a viable option. Primary resection of the external portion of the tumor was performed with interval resection of the pelvic extension of SCT. This approach may be useful in managing the common association of prematurity, large tumor, and hyperdynamic state. Because the primary cause of fetal mortality and morbidity is the vascular shunting through the tumor, there have been attempts to embolize or devascularize the tumor using radiofrequency ablation (Paek et al., 2001; Lam et al., 2002). In a report of four patients treated with radiofrequency ablation, two fetuses died secondary to hemorrhage after a significant portion of the tumor mass was ablated. The remaining two fetuses delivered at 28 and 31 weeks gestation with evidence of extensive necrosis of pelvic and perineal structures, necessitating extensive reconstructive surgery (Ibrahim et al., 2003). The uncontrolled nature of the energy delivered by the radiofrequency ablation device prevents its safe application in SCT, and this treatment modality has been abandoned.
A neonatologist should attend the delivery and be prepared to provide respiratory support. Careful handling of the infant is important to prevent exsanguinating hemorrhage into the tumor. Excellent venous access is paramount should hemorrhage in the tumor occur, and umbilical artery and umbilical venous catheters should be placed. The infant should be started on pressor agents such as dopamine or dobutamine to support the heart in its hyperdynamic state. Transfusion may be necessary immediately postnatally because hemorrhage into the tumor may have occurred during the delivery.
Severely premature infants should be intubated and treated for respiratory distress with surfactant-replacement therapy. Echocardiography should be obtained to assess the cardiac status of the newborn. Abdominal ultrasound examination can be performed at the bedside to assess the intrapelvic extent of tumor. If there is no high-output state then there is no urgency to resect the tumor, and attention should focus on the treatment of respiratory distress and correction of anemia. If a hyperdynamic state exists with an elevated cardiac output, attention should focus on supporting the newborn heart with inotropic agents and urgent resection of the SCT.
The goal ofthis resection is reversal of the high-output state, and this can usually be accomplished by resection of the exophytic portion of the tumor. Aortic occlusion by vessel loop to minimize hemorrhage when resecting an SCT in a severely premature infant has been effective in this setting (Robertson et al., 1995). Preoperative angiography and embolization and radiofrequency ablation have been used successfully as adjuncts to surgical resection of large vascular SCTs (Cowles et al., 2006). As with fetal resection of SCT, SCT resection in a premature infant should focus on eliminating the cause of the high-output state, not necessarily complete tumor resection. This can be accomplished by utilization of a thick tissue stapling device at the base of the SCT. If residual pelvic tumor remains, the urgency of resection can be guided by the pathology. The presence of yolk sac differentiation would necessitate earlier resection. In the absence of yolk sac differentiation, however, several months of growth of the infant can facilitate subsequent resection of the coccyx and the intrapelvic portion of the tumor. An abdominoperitoneal approach may be required for resection of the pelvic tumor. The operating table should be kept in a slight reverse Trendelenburg position to prevent air embolism (Seeds et al., 1982).
Staged resection may also be considered. In one report, a fetus in a high-output state due to an SCT 1.5 times its size underwent initial devascularization via ligation of the middle sacral and internal iliac arteries that eliminated the hyperdynamic high-output state and returned cardiac output to normal (Robertson et al., 1995). Thirty-six hours later, primary resection of the residual tumor was performed. The infant subsequently underwent resection of the intrapelvic portion of the tumor at 2 months of age, and is now 4 years of age and free of disease.
Massive hemorrhage is an important cause of neonatal death in large vascular SCTs undergoing resection. Coagulapathy resulting from massive hemorrhage may be an important contributing factor. Recombinant factor VIIa has been used successfully in this setting (Girisch et al., 2004).
The long-term outcome in newborns with SCT is generally excellent. The most important prognostic factor for SCT appears to be the age at diagnosis (Conklin and Abell, 1967). When the diagnosis is made prior to 2 months of postnatal age, or excision is performed prior to 4 months of age, the malignant potential is only 5% to 10% (Gross et al., 1951; Hickey and Layton, 1954; Waldhausen et al., 1963; Donnellan and Swenson, 1988). This increases to 50% to 90% ifthe diagnosis is delayed until after 2 to 4 months of age (Hickey and Layton, 1954; Altman et al., 1974).
The mortality in a newborn with SCT is, however, not primarily due to malignant potential, but rather from difficulty in resection, and possibility of tumor hemorrhage (Altman et al., 1974; Schey et al., 1977; Alter et al., 1988; Grisoni et al., 1988). Gestational age at diagnosis may also affect prognosis, as fetuses diagnosed with SCT after 30 weeks of gestation tend to fare better than those diagnosed earlier (Schey et al., 1977; Flake et al., 1986; Kuhlmann et al., 1987). Cystic tumors may carry a better prognosis, most likely because of the lower incidence of tumor hemorrhage or vascular steal (Hogge et al., 1987). Prompt excision of both the tumor and the coccyx is thought to be essential to prevent recurrence (Gross et al., 1987). Delay may result in infection, hemorrhage, pressure necrosis, and malignant degeneration (Holzgreve et al., 1985).
Although SCTs are usually benign, they are prone to recurrence and have malignant potential. Surveillance for tumor recurrence is essential postoperatively. In SCTs, AFP levels are a useful marker for possible recurrence; a consistent downward trend in values should be observed until normal levels are reached by 1 year of age. We currently recommend that all newborns with SCT have serum AFP levels measured and physical examinations performed, including digital rectal examinations every 3 months. Such surveillance is recommended for at least 3 years (Barreto et al., 2006). If the SCT was nonfunctional, postnatal pelvic sonographic examinations should be obtained at similar intervals. Once the serum AFP level normalizes, usually by 1 year of age, then MRI should be obtained on at least a yearly basis. Any increase over previous AFP values should prompt investigation for possible recurrence.
Factors that were thought to increase riskofrecurrence of SCT or malignant yolksac tumor were immature and malignant histology or incomplete resection. The chances of this recurrence was estimated at 11% by Derikx et al. (2006). Recurrence of the tumor does not necessarily indicate recurrence of malignancy. It should be treated as a premalignant lesion and excised. Even with malignant transformation of SCT, results with current chemotherapeutic regimens have achieved excellent survival rates. Misra et al. (1997) reported survival rates of 88% with local disease and 75% even in the face of distant metastases.
If the pathologic examination of the SCT reveals microscopic rests ofendodermal sinus tumor it remains controversial as to whether chemotherapy is indicated (Heerema-McKenney et al., 2005). Older studies suggested any amount of yolk sac tumor presaged a poor prognosis and aggressive treatment was indicated (Valdiserri and Yunis, 1981; Rescorla et al., 1998). More recent studies suggest the presence of yolk sac tumor, foci of fetal lines, and immature endodermal glands in the SCT are associated with an increased risk of recurrent yolk sac tumor (Hawkins et al., 1993; Heifetz et al., 1998). Those recurrences however are amenable to modern combination chemotherapy with excellent survival (Rescorla et al., 1998; Marina et al., 1999; Huddart et al., 2003; Heerema-McKenney et al., 2005; De Backer et al., 2006). As there is no consensus on this issue, the decision to treat microscopic rests of yolk sac tumor with combination chemotherapy will vary from institution to institution.
There is limited long-term outcome data in SCT patients. Fortunately, with benign SCT, there is usually no serious bowel or bladder dysfunction after surgery and most neonates do well following resection (Litwiller, 1969; Tapper and Lack, 1983; Gross et al., 1987). Neurogenic bladder, however, is not an uncommon sequela in SCTs with a large pelvic component. Ozkan et al. reported a series of 14 cases of neurogenic bladder with high grade reflux with abnormal bladder and urethral function following resection of SCTs (Ozkan et al., 2006). Similarly postoperative urologic sequelae in SCT have been ranged from 20% to 30% (Kirk and Lister, 1976; Lahdenne et al., 1992; Carr et al., 1997). Urologic functional recovery has been documented with increasing age (Engelskirchen et al., 1987; Carr et al., 1997). Bittmann and Bittman found 33% had impaired bowel and bladder function. The frequency of anorectal dysfunction has ranged up to 40% (Engelskirchen et al., 1987; Malone et al., 1990; Wooley, 1993; Boemers et al., 1994). The most common long-term complication after SCT resection was cosmetic dissatisfaction with operative closure (Bittmann and Bittmann, 2006). Some children may experience subtle gait abnormalities as a result of SCT and its resection (Zaccara et al., 2004).
GENETICS AND RECURRENCE RISK
Some cases of SCT appear to be familial, with a suggestion of an autosomal dominant inheritance (Hunt et al., 1977; Gonzalez-Crussi, 1982). Familial SCTs are more often type IV SCTs and can be easily missed (Gopal et al., 2007). While only 10% of nonfamilial SCTs are presacral, 100% of familial SCTs are presacral. Familial cases have a male to female rate of 1:1 compared to 1:3 ratio in nonfamilial cases. Familial cases can be associated with anorectal malformations, most commonly anal stenosis, and can present as part of Currarino’s triad (presacral tumor, anorectal malformation, and sacral anomaly) (Currarino et al., 1981). The familial cases are more likely to be associated with a “scimitar sacrum” and are usually benign (Gopal et al., 2007).
There have been rare cases ofchromosomal abnormalities reported in patients with SCT including distal 10q trisomy syndrome (Batukan et al., 2007), mosaic trisomy of the long arm of chromosome 1 (Wax et al., 2000), and de novo translocation between chromosome 2 and 7 (Le Caignec et al., 2003).
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