Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 3, 2011, pp. 451-454

Neurology India, Vol. 59, No. 3, May-June, 2011, pp. 451-454

Case Report

Falcine and parasagittal intracranial chondrosarcomas of the classical variant: Report of two cases with review of literature

Shyam S Krishnan¹, Manas Panigrahi¹, Dandu Varma², Sailaja Madigubba³

¹ Department of Neurosurgery, Krishna Institute of Medical Sciences, Secunderabad, Andhra Pradesh, India
² Department of Neuroradiology, Krishna Institute of Medical Sciences, Secunderabad, Andhra Pradesh, India
³ Department of Pathology, Krishna Institute of Medical Sciences, Secunderabad, Andhra Pradesh, India

Correspondence Address: Manas Panigrahi Department of Neurosurgery, Krishna Institute of Medical Sciences (KIMS), #1-8-31/1 Ministers Road, Secunderabad - 500 003, Andhra Pradesh India manaspanigrahi@live.com

Date of Submission: 02-Feb-2011
Date of Decision: 28-Feb-2011
Date of Acceptance: 01-Apr-2011

Code Number: ni11129

PMID: 21743182

DOI: 10.4103/0028-3886.82772

Abstract

Keywords: Chondrosarcoma, classical chondrosarcoma, dural chondrosarcomas, falx and parasagittal chondrosarcomas, intracranial extraskeletal chondrosarcoma

Introduction

Chondrosarcomas account for only 0.16% of all intracranial tumors; most lesions are skull-based and very rare locations include dura, choroid plexus and brain parenchyma. ^[1] Since the first description of intracranial extraskeletal chondrosarcoma by Mott in 1899, of the cases reported, dural-based lesions were 53 only and half of them were in falcine/parasagittal location. ^{[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11]} Only 10 cases of classical variant chondrosarcomas have been reported in the falcine/parasagittal location [Table - 1]. ^{[2],[3],[4],[5],[6],[7],[8],[9],[10],[11]} We report two additional such cases at this location.

Case Reports

Case 1

A 23-year-old lady presented with history of headache and vomiting, with episodes of giddiness and falls of 5 months duration. She also noticed clumsiness of her left hand. Clinical examination revealed subtle pyramidal signs in her left upper limb. Magnetic resonance imaging (MRI) of brain revealed a lobulated extra-axial anterior falcine lesion. The lesion was predominantly composed of components that were hypointense on T1- and T2-weighted images. The margin of the lesion as well as the interspersed T2 hyperintense components showed mild, heterogeneous contrast enhancement [Figure - 1]. There was superior sagittal sinus occlusion due to extension of the lesion. She underwent a right frontal craniotomy and total excision of the lesion along with the obliterated segment of superior sagittal sinus. The lesion was hard and lobulated, with the appearance of a stag horn calculus [Figure - 2]. Histological examination of excised lesion revealed well-differentiated chondrosarcoma showing lobules of cartilage containing atypical chondrocytes. There were few binucleated forms. There was no necrosis or significant atypia [Figure - 3]. Follow-up MR imaging at 16 months after surgery showed no residual or recurrent lesion.

Case 2

A 19-year-old boy presented with two episodes of seizures. The second episode resulted in a motor vehicle accident and a computer tomography (CT) revealed a right posterior frontal parasagittal lesion that was predominantly cystic and had a peripheral rim of calcification for which he was referred for further management. Neurologic examination was essentially normal. MRI of the brain revealed two components within the lesion: A superficial solid component that had heterogeneous signal intensity on T1- and T2-weighted images and showed moderate enhancement on post-contrast scans and a deep component that was cystic and had an enhancing wall [Figure - 4]. There was erosion of inner table of the skull overlying the lesion. He underwent a right frontal craniotomy and total excision of the lesion. The solid component of the lesion was firm to hard in consistency, while the cystic component had egg-shell like consistency with mucoid contents [Figure - 5]. Histopathological examination revealed well-differentiated chondrosarcoma showing lobules of cartilage containing atypical chondrocytes with cystic changes. There were few binucleated forms. There was no necrosis or significant atypia [Figure - 6]. Postoperative course was uneventful and there was no recurrence of tumor at 12-month follow-up.

Discussion

Intracranial chondrosarcomas are of three variants: Classical, mesenchymal and myxoid. ^[12] Chondrosarcomas commonly arise from the skull base. ^[13],[12] Extraskeletal chondrosarcomas of dural origin are rare and only 53 cases have been reported till date. ^{[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11]} While majority of the skull-base chondrosarcomas are of classical variant (over 80%), dural-based chondrosarcomas are predominantly of mesenchymal variant (60%) [Figure - 7]. Of the 25 falcine and parasagittal chondrosarcomas, only 10 cases were of classical variant [Table - 1]. The remaining cases were predominantly mesenchymal with only one myxoid variant. There was a strong female preponderance. ^{[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11]}

Skull-base chondrosarcomas are thought to arise from cartilaginous rests of the synchondrosis or from mesenchymal pluripotential cells of the meninges. Extraskeletal chondrosarcomas of dural origin are hypothesized to arise from metaplastic fibroblasts; from pleuripotent mesenchymal cells or cartilage cell rests in the dura due to their common mesenchymal origin with the skull vault. The rare intraparenchymal tumors are thought to arise from the pia-arachnoid cells of the Virchow-Robin spaces of intracerebral vessels. ^[3],[6] Histopathologically, classical variant shows less prominent cellular stroma with predominant cartilaginous lobules with pleomorphic cartilage cells. Classical variant has three histological grades: Grade I, II and III. Grade I tumors resemble benign cartilaginous tumors, whereas Grade II and III tumors are more cellular and exhibit more mitoses and less chondroid matrix. Mesenchymal chondrosarcomas have a biphasic pattern with undifferentiated mesenchymal cells among scattered islands of well-defined cartilage. Myxoid chondrosarcomas are intermediate grade lesions that can be differentiated histologically by the presence of mucinous supporting stroma. ^[12]

On imaging, these lesions are often mistaken as meningiomas due to their extra-axial location. They are typically hyperintense on T2-weighted and hypointense on T1-weighted images. Variable shortening of T1 and T2 relaxation times due to scattered mature cartilage cells make them heterogenous. On post-contrast study, classical variant shows a "honeycomb" pattern of enhancement while mesenchymal variant shows homogenous enhancement. Brighter signal on T2-weighted images and absence of dural tail differentiate them from meningiomas. ^[6],[7]

Skull base chondrosarcomas, where the classical variant is most common, have a recurrence rate of 25-53% with incomplete resection and at best 5% with total/near total resection. ^{[1],[9],[13],[14]} However, on review of the literature, we found there were no recurrences for dural-based classical chondrosarcomas after gross resection (the maximum follow-up period noted was 6 years). ^{[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11]} Both our cases had no recurrence on follow-up which was 12 months for one and 16 months for the other. Gross total resection would be the main stay of treatment as recurrences and metastases are rare in the dural classical variant. Radiosurgery may be required in cases with incomplete excision or in Grade 3 lesions. As nearly 50% of the mesenchymal and all the myxoid variants showed recurrence, adjuvant radiation therapy is given, but its role is debatable. Radiosurgery as an adjuvant to microsurgery is very effective in reducing recurrence. Role of proton beam is probably restricted to large inoperable tumors. ^[13],[14] Chemotherapy is usually reserved for metastasis. ^{[1],[5],[6],[9],[11],[12]}

References

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