Giant parietal lobe infantile gliosarcoma in a 5-year-old child.

The relative frequency of pediatric gliosarcoma (GSM) is 1.9% among glioblastomas and 0.5% among pediatric central nervous system tumors. A 5-year-old female child came to us with history of fever and loss of appetite since 2 weeks and right sided weakness since 4 days. Magnetic resonance imaging showed a large heterogeneously enhancing space occupying lesion in the left parieto-occipital region. A parieto-occipital craniotomy with radical excision of tumor was performed. The patient was given adjuvant therapy following surgery and survived until 9 months following surgery. The etiopathogenesis, treatment modalities and prognosis of GSM is discussed.

Introduction

Gliosarcoma (GSM) is a primary tumor of the brain composed of neoplastic glial cells in association with spindle celled sarcomatous elements.[1] It was first described by Stroebe but gained acceptance from detailed histological analyses of Feigin and Gross.[123] The 2007 World Health Organization classification scheme places primary GSM as a Grade 4 neoplasm and a variant of glioblastoma multiforme (GBM).[4] The relative frequency of pediatric GSM is 1.9% among glioblastomas and 0.5% among pediatric central nervous system tumors.[5] Ours is the second youngest case reported in literature and youngest with the lesion in the parieto-occipital region.

Case Report

A 5-year-old female child came to us with history of fever and loss of appetite since 2 weeks and right sided weakness since 4 days. She had history of generalized convulsion 3 months back and one more focal convulsion in right sided limbs 4 days back followed by same side limb weakness. She was lethargic and had preference to sleep but was easily arousable. There was history of headache that was holocranial and with morning exacerbation. On examination, her right sided limb power was 4/5. There was hypertonia and exaggerated reflexes in right sided limbs. Magnetic resonance imaging (MRI) showed a large heterogeneously enhancing space occupying lesion in the left parieto-occipital region causing significant mass effect and midline shift. The lesion was partly solid and partly cystic with rim enhancement and in close proximity to the occipital horn of the lateral ventricle [Figures 1 and 2].

Figure 1

The postcontrast axial image showing the large lesion in the left parieto-occipital region with peripheral contrast enhancement

Figure 2

The postcontrast coronal image showing the lesion with mass effect and displacement of the lateral ventricle

The patient was operated in right lateral position. A parieto-occipital craniotomy was performed, and the brain was found to be extremely tense. A small cortisectomy was done in the posterior parietal region and tumor identified [Figure 3]. The tumor was grayish in color, firm in consistency and had a good plane of cleavage from surrounding brain parenchyma. The lesion was excised completely in piecemeal fashion. The choroid plexus with ependyma was found adherent to the capsule that was preserved. Histopathology was suggestive of the malignant spindle cell tumor with densely packed tumor cells. Immunohistochemistry (IHC) was performed which was IHC-negative for glial fibrillary acidic protein and S-100. MIB-1 labeling index at some areas was up to 40%.

Figure 3

The small cortisectomy through which piecemeal excision of the tumor was performed

Postoperatively patient improved in sensorium and right sided limb power. The power was Grade 5/5 by postoperative day 1. The wound healed well and suture removal was done on day 9. Postoperative MRI done was suggestive of complete excision of tumor [Figure 4]. The patient underwent concurrent chemoradiation of 60 Gy along with temozolomide 75 mg/m2 on all days of radiation. The patient had headache and lethargy on postoperative day 15 for which a repeat imaging was done which showed hydrocephalus. We performed a ventriculoperitoneal shunt [Figure 5]. The patient improved following the cerebrospinal fluid diversion procedure. The patient was asymptomatic at 6 months followup. At 9 months following surgery, she got readmitted with drowsiness, decerebration, and respiratory tract infection. She expired even before repeat imaging could be done.

Figure 4

Complete excision of the tumor with residual enhancement of the choroid plexus of the ventricle

Figure 5

Enlarged ventricles with ventriculoperitoneal shunt in situ

Discussion

Gliosarcomas are rare and have an incidence of 1.8–2.8% of that of GBMs.[67] The diagnosis of GSM should be made when a tumor contains an admixture of two distinctive neoplastic tissues. One is an anaplastic astrocytoma, and the other resembles a fibrosarcoma.[38] Certain authors have suggested a presence of at least one atypical mesenchymal cell proliferation in one confluent medium power (×10 objective with ×10 eyepiece) field for a diagnosis of GSM.[9] Atypical components such as osteochondroma or osteosarcoma have been described in GSM.[1011]

There are two theories explaining the pathogenesis of GSM. Earlier theory suggested that the sarcomatous component originates from neoplastic transformation of hyperplastic blood vessels found in high-grade glioma.[2] The newer theory suggests monoclonal origin of both components of GSM with sarcomatous component originating via aberrant mesenchymal differentiation of the malignant glioma. This theory explains the absence of significant difference in clinical outcome between glioblastoma and GSM.[12] GSM has also been described following radiotherapy (RT).[59]

Even though several studies have showed no significant differences between GSM and GBM with regard to age, sex, size, clinical presentation, and median survival, they have been established to be two different pathologies.[31213] Some studies showed a temporal lobe predilection for GSM whereas others found no such difference.[3791213] The youngest case in literature of a 4-year-old child also showed tumor in the temporal lobe.[14] Table 1 shows the comparison of the other infantile GSM with our case. There have been anecdotal reports of the neoplasm in varied locations such as posterior fossa.[15] Few studies have also found that GSM tends to be smaller at presentation as compared to GBM.[9] In spite of these similarities, the two pathologies differ on intraoperative appearance (GSM similar to meningioma due to its well-circumscribed nature), tendency for extraneural metastasis and infrequency of epidermal growth factor receptor mutations.[31213]

Table 1

Comparision of the two youngest cases of gliosarcoma reported in literature

Gliosarcoma most commonly affects adults in the sixth or seventh decade of life and more commonly men (male: female ratio of 1.4–1.8:1).[613] A total of 24 cases of pediatric GSMs have been reported in the literature with a median age of 11 years with an increased incidence following exposure to RT.[5] The presenting signs and symptoms are consistent with those of expanding space occupying lesion such as headache, hemiparesis, seizures, and cognitive decline.[12]

Treatment modalities for GSM include tumor resection, postoperative RT and chemotherapy.[12] The median survival among all GSM patients has been reported to be 9 months; however, there are some variables that alter this.[13] Patients diagnosed prior to 50 years had a higher median survival period of 15 months as compared to 7 months for those diagnosed after age 50. Radical excision prolonged survival to 7–11 months as compared to 4 months with biopsy alone. RT increased the survival rate from 4 months to 10 months.[13] The role of chemotherapy is still uncertain with a few encouraging reports.[12]

Conclusion

Although gliosarcomas occur most commonly in the sixth or seventh decade and have a temporal lobe predilection, they can occur in any age group or any region. They should be considered in the differential diagnosis of all space occupying lesions. More dedicated studies are needed to understand the true nature of these biphasic tumors.