Synonyms: None.

Definition: Astrocytomas are intracerebral tumors of neuroectodermal origin. Histological findings are of an immense variety including astroblastomas, astrocytomas with fibrous, protoplasmatic or mixed forms, giant cell and anaplastic astrocytomas.

Histological grading: according to the WHO-definition summarizes benign¹, semibenign², semimalignant³ or malignant⁴ tumors, depending on isomorphisms or tumor cells¹, increased cell density or decreased isomorphism², increased polymorphism or necroses³ or multiformed, necrotic tissue with sinusoidal venous vessels within the tumor⁴.

Prevalence: 0.03-0.1:10,000 deliveries, 13% of all congenital brain tumors, 20% of all gliomas. M1:F1.

Etiology: The etiology of most brain tumors remains obscure, but the genetic nature of some is unchallenged; autosomal dominant diseases like neurofibromatosis, tuberous sclerosis or von Hippel-Landau disease are associated with tumors of the central nervous sytem, mainly astrocytomas.

Pathogenesis: Physical (X-rays), chemical and viral factors have been implicated in the pathogenesis of brain tumors, although the relationship to the development in humans has not been established.

Associated anomalies: Obstructive hydrocephalus.

Differential diagnosis: Teratoma.

Prognosis: Depends on the type of tumor and its operability: grade I: if totally removed, cure; grade II: 3-4 years; grade III: 2-3 years survival; grade IV: 14 months¹¹.

Recurrence risk: After complete removal: low; after partial resection: high. Not known for subsequent pregnancies.

Management: When large, as for disease with fatal outcome. Otherwise surgery and/or chemotherapy is recommended. Radiation in children under two years should not be applied because of the side effects.

MESH Astrocytoma BDE 0188 MIM 260500 ICD9 237.0 (Astrocytoma). 742.9 (Unspecified anomalies of the CNS) CDC 742.900

Address correspondence to: Christian M. Wilhelm, MD, Department of Obstetrics and Gynecology, University of Freiburg, Hugstetterstr. 55, 7800 Freiburg i. Br., Germany. Ph: 49-761-270-3002; Fax: 49-761-270-3053.

Introduction

Ultrasound diagnosis of fetal brain tumors is possible, when intracranial masses disrupt the normal architecture with or without hydrocephalus. Depending on the variety of congenital tumors^2,3,8,9, ultrasonic appearance can change from uniform solid or cystic lesions with well-defined borders to complete inhomogeneous tumors with irregular borders.

The location, size and the behavior of the tumor throughout the pregnancy, due to its rapid growth as well as increasing ventriculomegaly, may lead to preterm delivery or to the decision of the parents to terminate the pregnancy before viability^6,9.

Case report

This 31-year-old G₃P₂ was referred to our center at the 32^nd week of gestation with the suspicion of a fetal cerebral malformation. Ultrasound examinations between 32 and 35 weeks (fig. 1-2) showed a rapidly increasing intracerebral midline tumor of 40 to 65 mm.

Fig. 1: Ultrasound at 32 weeks, demonstrating a midline intracerebral tumor. Some areas of high and low echogenicity are demonstrated.

Fig. 2: Ultrasound at 35 weeks, demonstrating the growth of the tumor and the ventriculomegaly.

Additionally, ventriculomegaly with dilatation of anterior frontal horns (13 to 20 mm) and of posterior horns of the lateral ventricle (20 to 28 mm) was found.

Fetal swallowing and activity were normal. Additional malformations or polyhydramnios were excluded.

The tumor showed a primarily solid homogeneous echogenic structure, placed at the midline of the brain, extending from the suprasellar region to the skull, and from the frontal to the occipital region, limited here and on the parietal side by massively dilated lateral ventricles. During the latter pregnancy, additional central low echogenic or cystic structures were diagnosed within the tumor. The borders of the tumor were well defined. The diagnosis was intracerebral tumor with obstruction of the lateral ventricles, which rapidly increased during the following two weeks and was probably due to a hemorrhage. The biparietal diameter grew from 88 mm in the 32^nd week to 98 mm in the 34^th week, causing cranial enlargement.

To further characterize the mass and exclude an intracerebral hemorrhage, a MRI scan was done at 34 weeks (fig. 3).

Fig. 3: MRI at 34 weeks, demonstrating the tumor and the ventriculomegaly.

The diagnosis was symmetric intracranial tumor (i.e. plexus tumor). The MRI signals were not typical for pure hematoma, lipoma or arteriovenousmalformation. The tumor showed rapid expansive growth and a C-section was carried out in the 37^th week (2.630g male measuring 480 mm, with a head circumference of 340 mm).

Postpartum course

A postpartal ultrasound and MRI confirmed the prenatal findings of intracranial tumor with a mean diameter of 75 mm and venticulo­megaly. The clinical behavior of the newborn was normal. A stereotactic tumor biopsy demonstrated an astrocytoma (WHO-group II).

Biventricular shunts were placed at two months. The baby was referred at 3.5 months because of shunt infection. The tumor itself now showed signs of repeated hemorrhage without further growth. An intraventricular hemorrhage was diagnosed.

Within five months, the boy showed macrocephaly with pendulous nystagmus and fontanels under tension, requesting repeated shunt placement. Although the tumor was benign and showed no further growth, the initial size and type and the early onset with bad prognosis did not allow any surgical intervention. Therefore, only supportive care was decided upon with the parents.

Discussion

Definition

Brain tumors producing symptoms before the age of two months are classified as congenital tumors, because newborns are often initially asymptomatic¹.

Increasing ultrasound screening and experience may elucidate the incidence and ultrasound findings in the more frequent congenital brain tumors (e.g. teratoma, glioma, choroid plexus papilloma...).

Etiology and pathogenesis

The etiology of most brain tumors remains obscure, but the genetic nature of some is unchallenged; autosomal dominant diseases like neurofibromatosis, tuberous sclerosis or von Hippel-Landau disease are associated with tumors of the CNS, mainly astrocytomas. Physical (X-rays), chemical and viral factors have been implicated in the pathogenesis of brain tumors, although the relationship to the development in humans has not been established.

Frequency

Astrocytoma is one of the most frequent brain tumors in infancy. Over all, gliomas represent up to 76% of neoplasms in later childhood^1,3. Many of these tumors are described as large and well defined, and with rapid expansive, rather than infiltrative, growth. Their main complication is occlusion of the ventricular system with hydrocephalus³.

Jellinger et al² reported a series of 56 congenital tumors including probable or possible congenital intracranial neoplasms observed in a total of 730 intracranial tumors between ages 1 and 16 years, which corresponds to an incidence of 7.6%. In this series as well, neuroectodermal tumors, particularly gliomas, form the largest group, and almost three-quarters of congenital tumors are supratentorial.

Radkowsky et al⁸ reported 12 neonatal brain tumors that constituted 3.3% of pediatric brain tumors. After review of the literature, the incidence of congenital brain tumors may range between 0.5 and 7.6%^1-3,6,9.

Fig. 4: Frequency of microscopically verified central nervous tumors (n=589) during the first year of life¹².

Diagnosis

In this case, the sonographic findings were initially homogeneous, echogenic structure, with well-defined borders, occlusive internal hydro­cephalus and rapid growth. The echogenicity changed during the following weeks, suggesting intratumoral hemorrhage.

Differential diagnosis

Invasive intrauterine procedures for histologic grading are too dangerous and would be, in many cases, without practical consequence. MRI may be helpful to exclude intracerebral hemorrhage.

The other similar tumors that have been recognized include craniopharyngioma, cystic teratoma, choroid plexus papilloma and lipoma of corpus callosum^{4,5,7,8,10-12}.

Management

The prognosis depends on the size, growth and location of the tumor as well as the time of the initial diagnosis. These parameters determine the time and the mode of delivery. Rapid growth, large size, hydrocephalus and a central location are all pejorative factors.

References

1. Arnestein LH, Boldrey E, Naffzinger MC: A case report and survey of brain tumors during the neonatal period. J Neurosurg 8:315,1950.

2. Jellinger K, Sunder-Plassmann M: Congenital intracranial tumors. Neuropaediatrie 4:46,1973.

3. Jooma R, Kendall BE: Intracranial tumors in the first year of life. Neuroradiology 23:267,1982.

4. Kirkinen P, Suramo I, Jouppila P, et al: Combined use of ultrasound and computed tomography in the evaluation of fetal intracranial abnormality. J Perinat Med 10:257,1982.

5. Kwon TH, Jeanty P: Supratentorial arachnoid cyst. The Fetus 1:7429-1,1991.

6. Lacrampe MJ, Jeanty P: Craniopharyngioma. The Fetus 1:7429-11,1991.

7. Lipman SP, Pretorus DH, Rumack CM, et al: Fetal intracranial teratoma: US diagnmosis of three cases and a review of the literature. Radiology 157:491,1985.

8. Radkowski MA, Maidich TP, Tomita T, et al: Neonatal brain tumors: CT and MR findings. J Comput Assist Tomogr 12:10,1988.

9. Romero R, Pilu G, Jeanty P et al: Prenatal diagnosis of congenital anomalies. Norwalk, CT, Appleton and Lange, 1988.

10. Sauerbrei EE, Cooperberg PL: Cystic tumors of the fetal and neonatal cerebrum. Ultrasound and computed tomographic evaluation. Radiology 147:689,1983.

11. Strassburg HM, Sauer M, Weber S, et al: Ultrasonographic diagnosis of brain tumors in infancy. Pediatr Radiol 14:284,1984.

12. Voth D, Gutjahr P, Langmaid C: Tumours of the central nervous system in infancy and childhood. Berlin Springer Verlag, 1982.

13. Zimmermann RA: Magnetic resonance imaging of midline pediatric cerebral neoplasms. Acta Neurochirurgica 35:60,1985.