Hospital General de la S.S.A. Acapulco, Guerrero, Mexico. Facultad de Medicina de la Universidad Autonoma de Guerrero, Mexico. Instituto Mexicano de Diagnostico por Imagen, Acapulco, Mexico.

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 teratoma [7]. 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 presentation [3].

Case report

24-year-old G3P2 was referred for evaluation of the uterine size greater than the dates at 30 weeks gestation. The ultrasound revealed a 14.6 x 18.3 x 14 cm sacral mass consistent with sacrococcygeal teratoma. The amniotic fluid was slightly increased.

Images 1, 2: 30 weeks of gestation. Sagittal planes through the mass of sacral teratoma.

Images 3, 4: 30 weeks of gestation. Sagittal planes through the mass of sacral teratoma.

Images 5, 6: Postnatal appearance of the baby with massive sacrococcygeal teratoma.

Images 7, 8: Postnatal appearance of the baby with massive sacrococcygeal teratoma.

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 teratomas [8]. These pluripotential cells escape from the control of embryonic inducers and organizers and differentiate into tissues not usually found in the sacrococcygeal region [2]. 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 clinical presentation of sacrococcygeal teratoma is uterus size greater than dates [5].  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 myelomeningoceles, lipomas, hydromyelia, intracanalicular epidermoid tumors, dermal sinus stalks, extrarenal Wilms" tumors, retrorectal hamartomas, neuro­bla­stomas, and pacinomas [4]. Excluding meningo­mye­lo­cele and twin fetuses, a mass attached to the fetal rump is most likely a teratoma [6]. 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 nature [9]. Alpha-Fetoprotein can be normal or elevated in sacrococcygeal teratomas, but sono­graphy can distinguish these lesions from neural tube defects [10]. Early prenatal sonographic detection of sacrococcygeal teratoma allows for optimal perinatal obstetric and surgical management.

References

1. El-Quarmalawi MA, Saddik M, el Abdel Hadi F, et al. Diagnosis and management of fetal sacrococcygeal teratoma. Int J Gynecol Obstet 1990;31: 275-281.
2. Sheth S, Nussbau AR, Sanders R, et al. Prenatal diagnosis of sacrococcygeal teratoma: sonographic-pathologic correlation. Radiology 1988;169:131-136.
3. Ein SH, Adeyemi D, Mancer K. Benign sacrococcygeal teratomas in infants and children: a 25 year review. Ann Surg 1979;191:382-384.
4. Altman RP, Randolph JG, Lilly JR.  Sacrococcygeal teratoma: American Academy of Pediatrics Surgical Section survey - 1973. J Ped Surg 1974; 9:389-398.
5. 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.
6. Kuhlmann RS, Warsof SL, Levy DL, et al. Fetal sacrococcygeal teratoma. Fetal Therapy 1987; 2:95-100.
7. Lees RF, Williamson BR, Brenbridge AN, et al. Sonography of benign sacral teratoma in utero. Radiology 1980;134:717-718.
8. Romero R, Pilu G, Jeanty, P, et al. Prenatal diagnosis of congenital anomalies. Appleton & Lange 1988.
9. Sherowsky RC, Williams CH, Nichols VB, et al. Prenatal ultrasonographic diagnosis of a sacrococcygeal teratoma in twin pregnancy. J Ultrasound Med 1985; 4:159-161.
10. Holzgreve W, Miny P, Anderson R, et al. Experience with 8 cases of prenatally diagnosed sacrococcygeal teratomas. Fetal Therapy 1987;2: 88-94.
11. Flake AW, Harrison MR, Adzick NS ,et al. Fetal sacrococcygeal teratoma. J  Ped Surg 1986;21: 563-566.
12. Langer JC, Harrison MR, Schmidt KG, et al. Fetal hydrops and death from sacrococcygeal teratoma: Ratonale for fetal surgery. Am J Obstet Gynecol 1989; 160:1145-1149.
13. Hogge WA, Thiagarajah S, Barber VG, et al. Cystic sacrococcygeal teratomas:ultrasound diagnosis and perinatal management. J Ultrasound Med 1987; 6:707-710.