Primary spinal extra-osseous intradural mesenchymal chondrosarcoma in a young boy.

Primary spinal intradural mesenchymal chondrosarcoma is rare. We report the case of a 6-year-old boy to emphasize on the importance of considering this entity as differential diagnosis even when the lesion is purely intradural with no bony involvement.

Introduction

Mesenchymal chondrosarcoma is a primary malignant tumor of the bone and soft tissue, being extra-skeletal in 20-25% of the cases.[1] Most of these cases involve the central nervous system, with the majority being intracranial. To our knowledge there are only three previous reports of primary spinal intradural tumors without bony involvement in the English literature.[234]

Clinical Profile

A 6-year-old boy presented with progressively increasing upper backache and left lower limb weakness for 4 months. Examination revealed spasticity with exaggerated deep tendon reflexes in the left lower limb. The magnetic resonance imaging (MRI) showed a ventrally placed, 2 cm, well defined, intradural extramedullary, round lesion at T9, more on the left side displacing the cord to the right. It was hypointense on both T1 and T2-weighted images and enhancing with gadolinium [Figure 1]. There was no extradural or extra spinal involvement. The bone was normal. He underwent a left T9 hemilaminectomy and total excision of the tumor. At surgery, the tumor was firm with an attachment to the ventral dural. Post-operatively there was a significant reduction in spasticity. The histopathology was consistent with mesenchymal chondrosarcoma.

Figure 1

(a-c) Sagittal and (d-f) axial T1W, T2W and gadolinium enhanced images of a T1W intradural extramedullary 2 cm well defined mass with compression of the cord at T9. There was no extradural or extraspinal extension and the bone was normal

Discussion

Though schwannomas and meningiomas are the most common intradural extramedullary spinal tumors in adults, they are uncommon in children and hence the differential diagnosis of an intradural tumor should include Ewings sarcoma, soft-tissue chondroma, solitary fibrous tumor, hemangiopericytoma and metastasis from a neuroblastoma apart from mesenchymal chondrosarcoma. Meningiomas usually have a dural tail, but their occurrence in this age group is a rarity. Ewings sarcoma in this location too does not have unique radiological features and may appear iso-to hypointense on plain T1-weighted sequences and hypo-to hyperintense on T2-weighted magnetic resonance (MR) sequences, typically demonstrating enhancement after contrast administration. Occasionally hemorrhagic and cystic areas may be seen on the MRI.[5]

Solitary fibrous tumors have been reported to occur in the intramedullary, intradural and extramedulary compartments of the spine. They almost always show a characteristically hypointense signal on T2-weighted MR sequence.[6] Though this finding may be unique to this tumor type; meningiomas and hemangiopericytomas have been reported to show similar findings. Mesenchymal chondrosarcoma that involves the bone is osteolytic with ill-defined margins and occasional sclerosis. However, rarely they can present without any bony involvement. Li and Yao[3] have reported observing clear visible varices surrounding the cord as well as multiple punctuate regions of low intensity suggesting calcification – both of which were not seen in our case. Prominent contrast enhancement is universal. Some are lobulated with distinct margins.[4] Despite its advances, imaging is not conclusive and histopathological examination alone provides a definitive diagnosis. Even with adjuvant chemotherapy and radiotherapy the 5 year survival rates are in the range of 42-55%.[1] We suggest that the differential diagnosis of a primary intradural tumor in children should include tumors of mesenchymal origin.