Extrapineal mature teratoma of the posterior fossa in a child

doi:10.4236/ojped.2012.23041

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Open Journal of Pediatrics, 2012, 2, 257-259 OJPed

http://dx.doi.org/10.4236/ojped.2012.23041 Published Online September 2012 (http://www.SciRP.org/journal/ojped/)

Extrapineal mature teratoma of the posterior fossa in a

child

Mónica Rivero-Garvía, Javier Márquez-Rivas, Eloy Rivas, Ana Belén Rueda-Torres

Mónica Rivero Garvía, Division of Pediatric Neurosurgery, Hospital Virgen del Rocío, Manuel Siruot s/n, Seville, Spain

Email: [email protected]

Received 13 July 2011; revised 21 September 2011; accepted 19 July 2012

ABSTRACT

Introduction: Teratomas are non-malignantgerm cell

tumors commonly composed of cell types derived from

all of the three germ layers. Intracerebral teratomas

typically are midline o r paraxial lesio ns located in the

pituitary stalk or the pineal region. We report our

experience with mature teratomas of the posterior

fossa. Case report: We present the case of an 11-year-

old caucasian female with progressive headache that

caused interrupted sleep. Cerebral magnetic resonance

imaging showed a midline lesion in the posterior fossa

with mass effect and without contrast enhancement.

Anatomic pathology revealed a mature teratoma. Con-

clusion: Differential diagnosis of midline lesions in pe-

diatric patients must include teratoma s in spite of be-

ing posterior fossa lesions.

Keywords: Mature Teratoma; Posterior Fossa; Child;

Gross Total Reseccion; Extrapineal

1. INTRODUCTION

Teratomas are neoplasms that contain tissues derived

from the three germ layers: ectoderm (e.g. skin and hair),

mesoderm (e.g. adipose tissue), and endoderm (e.g. res-

piratory structures and digestive organs). Histologically,

these lesions are classified as something between germ-

cell tumors and dysembryoplastic neuroepithelial lesio ns.

In contrast to teratomas, epidermoid cysts are the lesions

derived from a single layer, that is, the ectoderm (e.g

keratin), while dermoid cysts are the ones derived from

two layers, the ectoderm and the mesoderm. The presence

of adipose tissue in these latter tumors constitutes the

main difference between them [1-4].

With a clear predominance in males, teratomas ac-

count for 0.2% of all intracranial tumors, although this

incidence increases to 2% in the first two decades of life

[1-3].

In this paper, we present the exceptional case of a pure

extrapineal mature teratoma of the posterior fossa.

2. CASE REPORT

We report the case of an 11-year-old Caucasian female

that presented with progressive headache that caused

interrupted sleep. Non-contrast computed tomography

(CT) of the head revealed a well circumscribed, hypoin-

tense lesion in the midline posterior fossa without ac-

companying edema (Figure 1). Contrast magnetic reso-

nance imaging (MRI) showed an extra-axial lesion in the

midline posterio r fossa with a mass effect that caused the

displacement of the vermis and the cerebral hemispheres.

(a) (b)

Figure 1. (a) Non-contrast axial CT scan of the head showing a

hypodense lesion in the posterior fossa in absence of associated

hydrocephalus; (b) Sagital T1-weighted image without contrast

revealing a hypointense tumor in the posterior fossa; (c) Sagittal

T2-weighted image showing a hyperintense lesion without

accompanying edema; (d) Contrast sagital T1-weighted show-

ing a lesion that does not enhance after contrast infusion.

OPEN ACCESS

M. Rivero-Garvía et al. / Open Journal of Pediatrics 2 (2012) 257-259

258

The lesion was hypointense on T1-weighted images and

hyperintense on T2-weighted studies, and showed no

enhancement after contrast administration. The main

diagnosis was epidermoid cysts. The patient underwent

suboccipital craniotomy (Figure 1). After V-shaped dural

opening, the tumor was explored, revealing the presence

of desquamated keratin as well as hair follicles sur-

rounded by a thin capsule (Figure 2). Gross total resec-

tion of the lesion was achieved.

The patient was not sequelae of the disease.

Histological study revealed components of all three

germ layers (e.g. keratin cyst formation, stratified squa-

mous keratinized epithelium, hair follicles, bone or adi-

pose tissue) (Figure 3). As a result, a mature teratoma

was finally diagnosed without malignant microfoci.

Alpha-fetoprotein and beta-HCG were not determined

preoperative because suspected diagnosis were epider-

moid cysts, neither postoperative because there were

Figure 2. Intraoperative image of the tumor showing

desquamated keratin and hair follicles.

(a) (b)

Figure 3. Anatomic pathology studies. (a) Keratin cyst for-

mation; (b) Stratified squamous keratinized epithelium; (c) Hair;

(d) Bone.

malignant microfoci and abdominal-CT did not show

other teratoma.

3. DISCUSSION

Intracranial mature teratomas are tumors with a very low

incidence (0.2%) and a clear male predominance (5:1).

This incidence is higher in pediatric patients (2%). In-

tracranial teratomas usually are located in the supraten-

torial midline and the pineal region [1-3]. We report the

case of an 11-year-old Caucasian female with a mature

teratoma in the midline posterior fossa.

Definitive diagnosis is achieved by means of a histo-

logical study, when tissues derived from the three germ

layers are identified.

Although no radiological alteration specific of these

lesions has been described, the presence of midline le-

sions in pediatric patients must take clinicians raise a

high index of suspicion of teratoma [2,5,6].

To our knowledge, only three cases of posterior fossa

mature teratomas have been reported in detail in the lit-

erature to date. However, they all present the cases of

adult patients an d only one of them is a midlin e teratoma

[1], being the other two ones paramedian. Further cases

on this matter describe the mature component in associa-

tion with immature tissue, other germ tumors, or as a

consequence of extra-cranial lesions.

When reviewing the literature, the case series of in-

tracranial pediatric teratomas reported by Noudel et al.

revealed pure mature teratomas in 5 out of 14 patients

with pure mature teratomas [2]. However, all of them

were located in the sellar or the pineal regions and none

of them in the posterior fossa. Kong et al. reported 6

cases of teratoma from a total case series of 36 patients.

Within these 6 cases, only one was settled in the poste-

rior fossa and all of them presented with a mixed histol-

ogy, where the mature teratoma was only part of the le-

sion [5]. On the contrary, our case describes a lesion that

histologically constitutes a pure mature teratoma. In lar-

ger series of pediatric tumors, such as the ones reported

by Rashidi M. et al., teratomas are not even described

[6].

In view of all these findings, we can now conclude

that this is the first case of midline posterior fossa mature

teratoma in a child published in the literature to date.

Complete surgical excision is the most effective

treatment in cases of benign intracranial lesions with

mass effect, and enables the patient’s cure. Other alterna-

tives, such as local radiotherapy, can cause a sudden in-

crease in the lesion size—as evidenced by Kong et al. [5],

as well as a higher risk of secondary neoplasms in pedi-

atric patients.

4. CONCLUSIONS

Differential diagnosis of midline lesions in pediatric pa-

M. Rivero-Garvía et al. / Open Journal of Pediatrics 2 (2012) 257-259

259

tients must include teratomas in spite of being posterior

fossa lesions.

Surgery is the main therapeutic approach and a com-

plete surgical resection is usually necessary to offer po-

tentially curative therap y to patients.

A definitive diagnosis is p rovided by histopatho logical

study when the presence of tissues derived from the three

germ layers is demonstrated.

REFERENCES

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