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|LETTER TO EDITOR
|Year : 2012 | Volume
| Issue : 1 | Page : 121-122
Intraparenchymal mesenchymal chondrosarcoma in an unusual location
Shashwat Mishra1, Ramesh C Mishra2, Kiran Chikkanhalli Subbarao3, MC Sharma3
1 Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
2 Department of Neurosurgery, Kamayani Hospital, Agra, India
3 Department of Neuropathology, All India Institute of Medical Sciences, New Delhi, India
|Date of Submission||28-Oct-2011|
|Date of Decision||22-Nov-2011|
|Date of Acceptance||29-Nov-2011|
|Date of Web Publication||7-Mar-2012|
Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi
|How to cite this article:|
Mishra S, Mishra RC, Subbarao KC, Sharma M C. Intraparenchymal mesenchymal chondrosarcoma in an unusual location. Neurol India 2012;60:121-2
We describe a patient with midline vermian mesenchymal chondrosarcoma, an extremely rare and aggressive tumor of the central nervous system (CNS).
A 30-year-old male presented with history of dizziness, headache and imbalance of two weeks' duration. Neurological examination revealed bilateral papilledema, cerebellar ataxia, nystagmus on bidirectional lateral gaze and mild incoordination in left upper limb. Computed tomography (CT) scan of the brain showed an intra-axial tumor in the cerebellar vermis with a dense calcific component [Figure 1]a and magnetic resonance imaging (MRI) showed a contrast enhancing lesion in the vermis [Figure 1]b and c. Patient underwent a standard median suboccipital craniectomy with total excision of tumor. The tumor was seen arising within the substance of the superior vermis as a vascular, pinkish fleshy mass with infiltration of the parenchyma at the margins [Figure 1]d. Patient made an uneventful postoperative recovery. Pathologically, the tumor demonstrated islands of hyaline cartilage amidst sheets of undifferentiated round cells with focal spindling and pleomorphism. The small round cells were vementin-positive and negative for CD 34 [Figure 1]e-j. Interestingly, no meningeal association was demonstrable either radiologically [Figure 2] or per-operatively. Following the pathological confirmation of the diagnosis of mesenchymal chondrosarcoma, patient received adjuvant radiotherapy. He underwent further screening for any skeletal lesions. He is presently asymptomatic (four months following surgery) and on regular follow-up.
|Figure 1: (a) Plain CT image showing an intraxial tumor in the cerebellar vermis with a densely calcified component. (b and c) Axial and sagittal T1-weighted contrast MR image of the tumor respectively, with the non-calcified portion enhancing. (d) Gross resected specimen. (e) (H and E, × 40) and G (H and E, × 100)-Islands of hyaline cartilage located amidst highly cellular undifferentiated small round cells. (f) (H and E, × 200) Undifferentiated small round cells with focal spindling and pleomorphism. (h-j) The small round cells were vimentin-positive and negative for CD 34. Immunohistochemical stains D (Vimentin, × 200), E (MIB-1, × 200) and F (CD34, × 100)|
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|Figure 2: Sequential MRI images showing no meningeal association of the lesion|
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Chondrosarcomas account for 6% of skull base tumors and only about 0.15% of intracranial tumors.  Pathological subtypes include: Conventional, dedifferentiated, clear cell and mesenchymal. The conventional variety is the most common and the mesenchymal variant is the rarest. The dedifferentiated and clear cell variants have not been reported in the CNS. Originally described by Lichtenstein and Bernstein, mesenchymal chondrosarcomas have been conventionally regarded to be a neoplasm of the bone. However, CNS happens to be the commonest extraosseous site of origin for these tumors.  Within the CNS, a primary intraparenchymal origin is distinctly rare. Most of the reports of intracranial mesenchymal chondrosarcomas acknowledge the secondary spread of these tumors to the brain parenchyma from either a primary dural or skeletal location. Within the CNS, these tumors frequently originate supratentorially in the craniospinal meninges. Only three previous cases in the literature have referred to a primary location of these tumors within the cerebellar parenchyma. 
Histopathologically, both skeletal and extraskeletal tumors exhibit similar features. Though variations are common, a characteristic bimorphic pattern is described on microscopy, with islands of hyaline cartilage interspersed with sheets or alveoli of undifferentiated small round cells.  The cartilaginous element is relatively well-differentiated and may resemble mature hyaline cartilage or low-grade chondrosarcoma. The transition between the two patterns may be quite abrupt and may lead to erroneous characterization if only a limited region is sampled. Immunohistochemical staining is indistinctive, the small round cells stain positive for CD99, vimentin and leu7. However, no characteristic molecular marker reliably differentiates it from other round blue cell tumors of the CNS. Thus the pathological identification primarily relies on the characteristic biphasic pattern.
A strong propensity for local recurrence is observed in mesenchymal chondrosarcomas with a reported rate of ~65%. The five-year mortality of this histological variant (54%) is also significantly higher than the conventional subtype (6%).  The extent of surgical resection is the crucial determinant of recurrence- free survival. Adjuvant chemotherapy protocol is not well-established for these tumors in view of their rarity; they have been mostly treated on the lines of soft-tissue sarcomas. Though adjuvant radiotherapy is routinely administered, there is no conclusive data regarding its efficacy in preventing recurrence. In our case, the patient underwent craniospinal irradiation as per Primitive Neuroectodermal Tumor (PNET) protocol.
| » References|| |
|1.||Cianfriglia F, Pompili A, Occhipinti E. Intracranial malignant cartilaginous tumours. Report of two cases and review of literature. Acta Neurochir (Wien) 1978;45:163-75. |
|2.||Louis DN, Ohgaki H, Wiestler OD, Cavenee WK. WHO Classification of Tumours of the Central Nervous System. WHO Classification of Tumours of the Central Nervous System. 4 th ed. Lyon: IARC Press; 2007. |
|3.||Lin L, Varikatt W, Dexter M, Ng T. Diagnostic pitfall in the diagnosis of mesenchymal chondrosarcoma arising in the central nervous system. Neuropathology 2012;32:82-90. |
[Figure 1], [Figure 2]