Immature Sacrococcygeal Teratoma with Microfoci of Yolk Sac Tumor in a Preterm Female Newborn-Is the Surgical Resection Enough?

Keywords

Newborn; Teratoma; Yolk Sac Tumor; Sacrococcygeal Region.

Introduction

Germ cell tumors (GCTs) originate from primordial germ cells with multipotent capacity for differentiation. These tumors are very rare in pediatric population, with overall incidence of 0.9 per 100.000 children up to 15 years [1]. GCTs are a heterogeneous group of neoplasms broadly divided in two classes: seminomas, consisting of ovarian dysgerminomas and testicular seminomas, and non-seminomas, which include teratomas, embryonal carcinomas, yolk sac tumors, and choriocarcinomas [2]. GCTs may occur both at gonadal and extragonadal locations. Extragonadal locations are present in about 60% of pediatric cases, with sacrococcygeal region being the most frequent [3, 4]. Approximately 80% of GCTs are benign, while 20% are malignant, representing about 2 to 3% of all malignant pediatric tumors [5]. Two main malignant subtypes of GCTs in children are yolk sac tumor which produces alpha-fetoprotein (AFP) and choriocarcinoma which produces beta-human chorionic gonadotropin (βHCG). Teratomas, the most common GCTs, are comprised of components derived from all three embryonic layers. According to the histology, they are classified as mature, immature and malignant.

We report a case of a premature female newborn with large sacrococcygeal tumor that was first noticed at birth. The child was in a life-threatening condition, requiring urgent diagnostic procedures.

Case Presentation

A female newborn was delivered vaginally at 29th week of gestation due to premature rupture of membranes. She was the second child from the second pregnancy of a healthy 35-yearold woman. Cerclage placement was done at 21th week of gestation because of cervical insufficiency. Fetal ultrasounds were performed regularly and were described as normal. Birth weight, length and head circumference were according to the gestational age (1230 g, 36 cm, and 28 cm respectively). Apgar scores were 6 and 7 at 1 and 5 minutes, respectively. At birth, a sacrococcygeal mass 6 cm in diameter was observed, covered with shiny skin with prominent blood vessels, suspicious for myelomeningocele (Figure 1). Few hours after delivery respiratory distress syndrome developed, that required mechanical ventilation and the surfactant. Because of the risk of perinatal infection, empirical antibiotic therapy with ampicillin and gentamicin was initiated. Intraventricular hemorrhage grade 2 was diagnosed. Considering poor general status of the newborn, urgent diagnostic procedures were done. Plain radiography was performed to exclude congenital spinal abnormalities. Ultrasound demonstrated a large exophytic solid mass with cystic components, calcification, and neovascularization. Ultrasound-guided fine needle aspiration was done; with the cytology finding suggestive for teratoma. AFP level was normal for gestational age (123,420μg/L). Magnetic Resonance Imaging (MRI) of the abdomen and pelvis showed solid-cystic mass with lobulated internal structure, encapsulated towards rectum and delimited towards the uterus and vagina (Figure 2). Distal neural tube defect was excluded, suggesting type 2 SCT according to Altman classification [6]. After cardiopulmonary stabilization, complete tumor resection with coccygectomy was performed on the 18th day of life. Histology demonstrated grade 3 immature teratoma with microfoci of yolk sac tumor (Figure 3). The postoperative course was uneventful. Computed tomography (CT) of the chest and bone scan excluded distant metastases. There were no associated structural urinary or gastrointestinal abnormalities. Control MRI confirmed the absence of residual tumor. The child was discharged at the age of 2 months. She has been followed-up regularly, and at the age of 3 years she is in complete remission with normal urinary function and bowel movements. Because of the cerebral palsy due to intraventricular hemorrhage, the girl is included in the habilitation program.

×

Figure 1:

Close

Figure 1. Large sacrococcygeal tumor observed postnatally.

×

Figure 2:

Close

Figure 2. MRIof the abdomen and pelvis (sagittal plan) on T2 weighted images showing type 2 SCT according to the Altman classification.

×

Figure 3:

Close

Figure 3. Immature teratoma (A) with yolk sac tumor components (B), immature cartilage and surrounding blastemal cells (C) and primitive neural tube-like structures (D).

Discussion

SCT is a rare tumor, with the prevalence of 1 per 27.000 live births and marked female predisposition [7]. Prenatal diagnosis is established during routine ultrasound in the second trimester in about half of cases [7, 8]. Hydrops fetalis, high-output cardiac failure, and coagulopathy can develop during the fetal life. Perinatal complications include preterm labor, dystocia, spontaneous tumor rupture or hemorrhage, polyhydramnios or oligohydramnios, and maternal mirror syndrome. At birth, sacrococcygeal tumor with or without signs of the rectum and/or bladder obstruction is generally seen. SCT can be associated with the abnormalities of the nervous, cardiac, urogenital or musculoskeletal system. The most important differential diagnosis for perinatal sacrococcygeal mass includes distal neural tube defects (i.e. meningocele, myelomeningocele or myelocystocele) and neurogenic tumors (ganglioneuroma and neuroblastoma) [9]. Lipoma, hamartoma, lymphangioma, hemangioma, enteric cyst, sacral chordoma, and ependymoma are other differential diagnoses of SCT [10].

Etiology of SCT is still not well understood, but is believed to originate from totipotent cells of Hensen’s node and primitive streak. Considering biological capability for continuous embryonic growth, mature teratoma may become malignant. Very few genetic studies have been performed in pediatric teratomas, and no consistent genetic changes have been identified. In contrast, yolk sac tumors of infancy are characterized by gain of chromosomes 1q and 20q, and loss of chromosomes 1p and 6q [11, 12].

Diagnostic imaging of choice is CT or MRI of the abdomen and pelvis, to delineate tumor and to visualize surrounding tissues and organs, especially intraspinal involvement. Chest CT and bone scan is performed for the staging. Detection of AFP may help to confirm the diagnosis. Grading and classification of teratomas is the mainstream for further management. The tumors are classified according to Altman Classification into four types: Type I is predominantly external with a minimal intrapelvic component; Type II is predominantly external with large intrapelvic extension; Type III is predominantly intrapelvic with small external mass, and Type IV is entirely internal. Approximately 45% of teratomas are Type I, 35% are Type II, 10% Type III, and 10% Type IV [6]. WHO classification of GCTs based upon histology distinguishes mature, immature and teratomas with malignant transformation. Immature elements usually contain neuroepithelium, primitive mesenchymal tissue or cartilage. The Gonzales - Crussi grading system [14] refers the grade of immaturity: Grade 0 - mature teratomas with completely differentiated tissue; Grade 1 - teratomas with less than 10% of immature tissue; Grade 2 - teratomas containing among 10% to 50% of immature tissue, and Grade 3 - teratomas consisting of more than 50% of immature tissue. Mature teratomas (G0) are more frequent (54.5%) than immature teratomas (G1-G3, 45.5%). The highest grade of immaturity is present in 7.8% of all teratomas [13].

The cornerstone of the treatment is complete surgical resection [8, 15-18]. Macroscopically, teratomas may be cystic, predominantly solid, or a mixture of solid and cystic components with variable amounts of necrosis [13]. SCTs often do not have a capsule or pseudo capsule, which contributes to the difficulty to achieve complete resection.

The important feature of SCTs is the great rate of relapses. Most relapses occur at the primary site (11% to 49%). Risk factors for recurrence are incomplete resection, immature and malignant histology [16, 19, 20]. Recurrent SCT is usually more undifferentiated/malignant [16]. The 5-year EFS of patients with complete resection is 92%, comparing with 69% in patients with microscopic residues and 38% in patients with macroscopic residual tumor [15]. Therefore, early and complete resection of the primary tumor with coccygectomy must be considered.

SCTs with malignant elements of yolk sac tumor are generally not seen in infants. Only 1.5% of the tumors are malignant when diagnosed and treated in the first week of life, whereas the rate of malignancy is nearly 40% in children older than 1 year [16].

The optimal treatment of patients with completely resected (stage I) immature teratoma with malignant elements is controversial. For many years the standard approach for patients with stage I SCT with malignant elements (yolk sac tumor, embryonal carcinoma or choriocarcinoma) was surgical treatment and chemotherapy [15, 21]. Two therapeutic strategies have been employed: adjuvant chemotherapy after primary resection, or neoadjuvant chemotherapy followed by resection and adjuvant chemotherapy. Most commonly used is carboplatin-etoposidebleomycin regime [17, 22].

Recently, observation without chemotherapy has been suggested. In Pediatric Oncology Group/Children's Cancer Group Study, 4 out of 23 of patients with immature teratoma containing malignant foci who did not receive chemotherapy had recurrence, suggesting that surgical resection followed by close observation is effective treatment [22]. In the study by Gobel et al, 3 patients with stage I malignant SCT did not receive chemotherapy and had no recurrence at 5 years [15]. In recent study by Egler et al., 4 patients with stage I SCT with malignant elements had no recurrence after 3 years of close surveillance [23]. Considering small series of patients in these studies, definite recommendations for treatment of patients with stage I immature teratoma with malignant elements still need to be established.

Long-term follow-up is recommended, including physical examination, tumor marker assessment, and imaging studies. The interpretation of AFP levels should be done in additionto age and clinical parameters, as both benign and immature teratomas may produce modest elevations in AFP and β-HCG [24]. The American Intergroup data showed 5-year OS and EFS for patients with immature teratoma with yolk sac elements of 83% and 80%, respectively [25]. At least one third of patients had some degree of functional impairment, including bowel or bladder incontinence, vesicoureteral reflux, recurrent urinary tract infections, and cosmetic problems [8].

We present a rare case of a newborn with immature SCT containing malignant components. Prenatal diagnosis was missing although ultrasound examinations were performed regularly. Wellplanned complete surgical resection was lifesaving. Considering that no firm guidelines for adjuvant chemotherapy exist, as well as very young age of the patient, and acute and long-term side effects of chemotherapy, we decided to monitor patient closely. At 3-year follow-up, she has no clinical or radiological evidence ofrecurrence, with maintained good urinary and anorectal function.

Conclusion

Newborns with SCT, including rare undifferentiated tumors with malignant elements, have a good prognosis depending on timely recognition and early surgical intervention. Prenatal diagnosis and prenatal close follow-up are of utmost importance, significantly reducing fetal and neonatal morbidity and mortality. Perinatal management requires multidisciplinary team consisting of an obstetrician, neonatologist, radiologist, pediatric surgeon, anesthesiologist, pathologist and pediatric oncologist. Complete surgical excision is the mainstay of the treatment. Optimal treatment of infants with malignant SCT is still evolving. Considering the risk for tumor recurrence, long term follow-up is mandatory.