Chapter 115
##### KEY POINTS

Key Points

• 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.

##### CONDITION

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 ...