Beer Sheva, Israel

Definition: A tumor originating from a multipotential embryonic cells, situated in the so called Hensen"s node ( Primitive knot), a part of the primitive streak.

Pathology: Mature and immature teratomas represent 87% to 93% of all cases. Malignant tumors represent other 7 % to 13%[1]. The neurologic tissue represents a major constituent.

Classification

TYPE 1 : Predominantly external, with minimal presacral componrent.

TYPE 2 : Predominantly external, with significant intrapelvic component .

TYPE 3 : Predominantly internal, with abdominal extension.

TYPE 4 : Entirely internal with no external component .

Type 1 and 2 include 80 % of the cases[2]. Only 10% of the SCT are of type 4[3]. Of this group, only 15% are entirely cystic. The presence of functioning choroid plexus, is thought to be responsible for the cystic component[4].

Incidence: 0.02-0.03:10,000 live births[5]. Approximately 80% are female (M4:F1)[6],[7].

Recurrence: The majority are sporadic. 26 cases of familial hereditary pattern were reported until 1989[8],[9]. 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
• It was usually benign.

Differential diagnosis of presacral cystic masses

1)      Anterior meningocele ( ASM) . It rarely coexist with SCT in the same fetus. Only 6 such cases reported in the literature until 1989. Currarino syndrome (a triad consisting of anorectal malformations, sacral bony defect, and presacral mass, benign teratomas) It represents 18 % of the presacral masses[10].

2)      Neuroectodermal cyst[11]

3)      Perineuronal cyst (Tarlov"s cyst)[12]

4)      Gastrointestinal:

a.       Rectal obstruction / dilatation.

b.      Bowel duplication.

c.       Meconium pseudocyst.

5)      Retroperitoneal tumor of mesenchymal origin

6)      Ovarian cyst

7)      Pelvic kidney cyst

Associated anomalies: Reported incidence in postnatal studies: 5 % to 25% . Involving various systems with no specific pattern[13]. Prenatal series , in contrast , did not report any case of associated malformations including aneuploidies (Ref. 15- 30 , Tab 1.)

Table 1

Sacrococcygeal Teratoma : Outcome – Prenatal series