SACROCOCCYGEAL TERATOMA

· Sacrococcygeal teratomas arise from a multipotential embryonic cell situated in Hensen’s node, a part of the primitive streak. A theory of "twinning accident" with incomplete separation during embryogenesis has also been proposed.

· Mature and immature teratomas represent 87-93% of cases, with malignant tumors representing the other 7-13% (1) (malignant change occurs more commonly in males) (2).

· The majority occurs sporadically, however a familial hereditary pattern has been reported. Unlike the sporadic type, the familial type is usually benign and entirely presacral. There is an equal male to female distribution and may be associated with anal stenosis and a sacral defect.

· Sacrococcygeal teratomas occur in approximately 1:40,000 births (1).

· Female: male ratio is 4:1.

· Benign versus malignant:

o It was usually benign. Benign - disease free survival is greater than 90%

o Malignant - significant mortality, although good progress has been made recently in treatment of these tumors.

• Time of diagnoses is key:

1. < 2 months of age, only 7-10% are malignant
2. Age 1 year, 37% malignant
3. Age 2 years, 50% malignant

EMBRYOLOGY / ETIOLOGY

o Though the exact etiology of most SCTs is unknown, the majority are thought to be sporadic.

o A few families with autosomal dominantly inherited presacral teratomas have been described in the literature, however. The recurrence risk for this family is probably not significantly above background [10].

The familial type of SCT has different characteristics with:

· Female to male ratio of 1:1

· It was entirely presacral in all cases.

· It was associated with anal stenosis and sacral defect together, and

Link to Embryology / Etiology

CLASSIFICATION (2)

• Sacrococcygeal teratomas are classified according to the degree of exterior component or intrapelvic extension
1. Type I (46.7%) is a predominantly external tumor with minimal presacral content.
2. Type II (34.7%) is a large external tumor with significant intrapelvic extention.
3. Type III (8.8%) is a mass that is apparent externally but whose mass is predominantly pelvic or abdominal or both.
4. Type IV (9.8%) is a tumor that is presacral and entirely internal with no external manifestations.

ULTRASOUND

Link to Ultrasound

ASSOCIATED ANOMALIES

15% of patients have associated congenital anomalies: genitourianr, imperforate anus, sacral bone defects, duplication of uterus or vagina, spina bifida, meningomyelocele.

COMPLICATIONS

External sacrococcygeal teratomas have a significant risk of dystocia, hydrops, hemorrhage, congestive heart failure and rare malignancies (6-11). Other complications in utero include polyhydramnios and tumor hemorrhage, which can lead to anemia and nonimmune hydrops fetalis. If significant atrioventricular (A-V) shunting occurs within the tumor, hydrops may result from high-output cardiac failure. Development of hydrops is an ominous sign. If it develops after 30 weeks’ gestation, the mortality rate is 25%. If recognized, delivery is recommended as soon as lung maturity is documented. Development of hydrops before 30 weeks’ gestation has an abysmal prognosis, with a 93% mortality rate.

Inadequate placental flow has been reported to induce the release of vasoactive substances that can gain access to the maternal circulation that result in endothekial cell damage and lead to maternal pseudotoxemia (Ballantyne syndrome). In this syndrome there are signs and symptoms of pre-eclampsia including hypertension, proteinuria, peripheral edema, pulmonary edema, nausea and vomiting (17-19).

DIFFERENTIAL DIAGNOSIS

• Fetal ovarian cyst (usually paramedian and not in the midline).
• Anterior meningocele (may rarely co-exist with sacrococcygeal teratoma in the same fetus).
• Hematometra.
• Dilated loops of bowel or duplication cysts appear cystic, however they are not usually situated so low in the pelvis. Rectal duplications may, however, be in the pelvis.
• Hydronephrotic pelvic kidney.
• Lymphangioma, cystic neuroblastoma, or bladder duplication may occur in the fetal lower abdomen.
• Neuroectodermal cyst (13) - derived from the posterior neuropore.
  Although it is benign it is anechoic and may be indistinguishable from a cystic sacrococcygeal teratoma.
• Perineural cyst (Tarlov’s cyst) (14).
• Meconium pseudocyst.
• If the tumor is located internally the differential diagnosis includes: meconium pseudocyst, ovarian cyst, hydrocolpos, bowel duplication, bowel dilatation, mesenteric cysts, bladder duplication or cystic neuroblastoma.
• If the tumor is external, the differential diagnosis includes myelomeningocele.
• If the tumor is solid, the differential diagnosis includes cordomas, neurogenic tumors, lipomas, hemangiomas and malignant melanomas.

MANAGEMENT AND PROGNOSIS

Holzgreve et al (15,16) 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. 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 intervention.

TREATMENT

Treatment of SCT is primarily surgical. Sacrococcygeal teratomas should be excised as soon as possible, because small, undifferentiated foci may proliferate and become aggressive. If diagnosed in utero, then intrauterine resection is recommended. Since the tumors are attached to the coccyx, the entire coccyx must be removed. Failure to remove the coccyx results in a 30 to 40 per cent risk of local recurrence.

A procedure, called "radiofrequency ablation", developed at the University of California San Francisco has proven successful in a number of cases. A needle is inserted through the maternal abdomen into tumor. Radiofrequency waves are sent through this needle, supplying heat to the tumor and destroying the blood vessels that feed it. Without vascularity, the tumor regresses and the hydrops, or heart failure is reversed.

REFERENCES

1. Valdiserri RO, Yunis EJ. Sacrococcygeal teratoma: a review of 68 cases. Cancer 1981;48:217-221.
2. Altman RB, Randolph JG, Lilly JR. The American Academy of Pediatrics Surgical Section (AAPSS) Survey. J Pediatr Surg 1974;9:389-398.
3. Gross RE, Clatworthy HW, Meeker IA. Sacrococcygeal teratoma in infants and children. Surg Gynecol Obstet 1951;92:341.
4. Altman RP, Randolph JG, Lilly JR. Sacrococcygeal teratoma: American Academy of Pediatrics Surgical Section Survey - 1973. J Pediatr Surg 1974;9:389.
5. Hogge WA, Thiagarajah S, Barber VG et.al. Prenatal diagnosis of sacrococcygeal teratoma: Ultrasound diagnosis and perinatal management. J Ultrasound Med 1987;6:707.
6. Ashcroft KW, Holder TM. Hereditary presacral teratoma. Pediatr Surg 1974;9:691.
7. Sheth S, Nussbaum AR, Sanders RC et.al. Prenatal diagnosis of sacrococcygeal teratoma: Sonographic - pathologic correlation. Radiology 1988;169:131.
8. Gross SJ, Benzie RJ, Sermer M et.al. Sacrococcygeal teratoma: Prenatal diagnosis and management. Am J Obstet Gynecol 1987;156:393.
9. Chervenak FA, Isaacson G, Touloukian R et.al. Diagnosis and management of fetal teratomas. Obstet Gynecol 1985;66:666.
10. Seeds JW, Mittelstaedt CA, Cefalo RC et.al. Prenatal diagnosis of sacrococcygeal teratoma: An anechoic caudal mass. J Clin Ultrasound 1982;10:193.
11. Lees RF, Williamson BRJ, Brenbridge ANAG. Sonography of benign sacral teratoma in utero. Radiology 1980;134:717.
12. Shipp TD, Shamberger RC, Benacerraf BR. Prenatal diagnosis of grade IV sacrococcygeal teratoma. J Ultrasound Med 1996;15:175-177.
13. Bloechle M, Bollmann R, Wit J, et.al. Neuroectodermal cyst may be a rare differential diagnosis of fetal sacrococcygeal teratama: first case report of a prenatally observed neuroectodermal cyst. Ultrasound Obstet Gynecol 1996;7:64-67.
14. Tarlov IM. Spinal perineural and meningeal cysts. J Neurol Neurosurg Psychiatry 1970;33:833.
15. Holzgreve W, Flake AW, Langer JC. The fetus with sacrococcygeal teratoma. In Harrison M, Golbus M, Filly RA (eds). The unborn patient. Philadelphia: WB Saunders 1991, p460-9.
16. Holzgreve W, Miny P, Anderson R, et al. Experience with 8 cases of prenatally diagnosed sacrococcygeal teratomas. Fetal Therapy 1987;2: 88-94.
17. Roberts JM, Taylor RN, Musci TJ et.al. Preeclampsia; an endothelial cell disorder. Am J Obstet Gynecol 1989;161:1200-1205.
18. van Selm M, Kanhi HH, Gravenhorst JB. Maternal hydrops syndrome: a review. Obstet Gynecol Surv 1991;46:785-788.
19. Heyborne KD, Chism DM,,. Reversal of Ballantyne syndrome by selective second trimester fetal termination: a case report. J Reprod Med 2000;45:360-362.