Introduction

Sacrococcygeal teratomas (SCT) are one of the most common teratomas. However, the malignant types of these tumors are still relatively rare (1). SCT are more common in girls then in boys. The majority of SCT in neonates are benign, but the probability of malignant degeneration advances in the first months of life (2). Yolk sac tumors (YST) are rare and highly malignant tumors, occuring in children as well as in young adults. In the past, the outcome of these tumors was very poor and the prognosis was almost always fatal. With the refinement of chemotherapeutic options in the last several decades survival rates have improved.

Case report

We report on a female term newborn (birth weight: 3580g) delivered by caesarean section, APGAR Score 9/10/10. After delivery an unknown sacrococcygeal tumor mass was visible. Neurological assessment was normal. There was no constipation or anuria. Physical examination revealed abdominal meteorism.

Ultrasound of the sacrococcygeal region showed a mass consisting solid and cystic parts as well as vascular signs (diameter: 1,5 cm). The Alpha Fetoprotein (AFP) levels were in the upper normal range (91 006 ng/ml; normal range in newborns: mean 48406 +/- 34718 ng/ml). A complete tumor resection including the os coccygeum was performed. The resection margins were free of tumor. The preoperative clinical diagnosis was a teratoma, but histological examination of the surgical specimen revealed a typical yolk sac tumor of extragonadal origin. Immunohistochemical evaluation of the tumor was positive of AFP and cytokeratin (AE1 /AE3).

Figure 1

Fig. 1: Morphological and immunohistochemical evaluation.

A, highly cellular non-capsulated yolk sac tumor showing an infiltrative growth into adjacent soft tissue structures. B, higher magnification in some areas revealed a microcystic growth pattern with a high degree of vascularization. C, lots of characteristic Schiller-Duvall bodies were found, consisting of small tumor cells arranged in a perpendicular pattern around small thin walled blood vessels. D, immunohistochemistry revealed a cytoplasmic expression of AFP in a subset of tumor cells.

Postoperative staging examinations revealed the occurence of a secondary metastasis with a diameter of 7 mm in the abdominal wall, which was completely resected at the age of six weeks.

Figure 2

Fig. 2: Secondary metastasis of the yolk sac tumor in the abdominal wall (A) and the pre-sacral relapse (B)

The newborn received four cycles of a chemotherapy, containing cisplatin (20 mg/m2 for 5 days) and etoposide (100 mg/m2 for 3 days). AFP levels decreased after two cycles.

Figure 3

Table 1 : Alpha Fetoprotein

A local relapse in the pre-sacral region was diagnosed after 4 cycles (AFP maximum: 682 ng/ml). 4 cycles of hyperthermia (41- 41.6°C) combined with cisplatin, etoposide, cyclophosphamide day 1 and 4 and etoposide and cyclophosphamide day 2 and 3 followed. A complete surgical resection of the relapsed tumor including the top of the os sacrum was performed after the third cycle. Despite of the multimodal therapeutic regime, the patient died due to rapid tumor progress.

Discussion

The YST was first identified as a germ cell tumor by Teilum in 1946 (3). It is found in the testes, ovaries, and several extragonadal sites including the pre-sacral area and anterior mediastinum. Whereas most of the benign tumors are seen in newborns, the malignant form occurs predominantely after the first year. Malignant YST in newborns are extremely rare. The incidence of teratomas with YST is about 5.8 %. 2 to 10 % of these tumors are malignant up to the age of four months. After this age, the rate of malignancy increases steeply up to 50-90% (1). The event free survival rates at presentation are about 70 %.

A YST of the sacrococcygeal region with dissemination in the abdominal wall is uncommon and has not been reported in the literature. The unusual way of dissemination has to be discussed.

The histogenesis of primary YST is still unclear. First, it has been suggested that YSTs might originate from the germ cells that escaped their migration course from the yolk sac to the genital ridge during embryogenesis (4,5). Second, the embryonic cell theory favors the persistence of pluripotentic embryonic cells, which escaped from the influence of the differentiation process during embryogenesis.

Yolk sac tumors show an infiltrative growth into adjacent soft tissue structures, higher magnification in some areas revealed a microcystic growth pattern with a high degree of vascularisation. Lots of characteristic Schiller-Duvall bodies can be found, consisting of small tumor cells arranged in a perpendicular pattern around small thin walled blood vessels. Immunohistochemistry reveales a cytoplasmic expression of AFP in a subset of tumor cells (6).

YST express high blood levels of AFP. But age depended normal values of AFP in newborns have to be considered.

Heerema-McKenney et al. even found no correlation between AFP elevation above mean values for gestational age and the presence of YST at all (7).

Therapeutic regimes are scale and not well established. Radical surgical resection is the most important strategy (7).

The most effective chemotherapeutic agent is cisplatin but in newborns this drug is an extremely toxic agent. However, the outcome of malignant sacrococcygeal germ cell tumors, which were not treated with cisplatin, is almost always fatal (8). Therefore combined chemotherapy with reduced dosis, in combination with hyperthermia might be a new therapeutic strategy. Due to the rare cases, experience in this strategy is missing.

Second-look surgical procedures of residual tumors (primary or metastasic site) may improve the survival rates.

Radiotherapy was not planned to avoid growth disturbances and to receive the fecundity.

Significant improvement of survival rates might be obtained by a combination of surgery, chemotherapy and radiotherapy (9).

Better characterisation of the biologic and pathologic features of this tumor entity is still needed as well as the knowledge of the clinical behaviour to improve the survival rates. Due to the rare incidence in neonates clinical studies are needed but missing.