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Neurology India, Vol. 59, No. 5, September-October, 2011, pp. 783-785 Letter to Editor Synovial sarcoma of cervical intervertebral foramen: A rare cause of brachial weakness Prashant S Naphade1, Meena S Desai2, Rajan M Shah3, Abhijit A Raut1 1 Department of Radiology, Seven Hills Hospital, Mumbai, India PMID: 22019681 DOI: 10.4103/0028-3886.86575 Synovial sarcoma (SS) is a rare malignant mesenchymal tumor and accounts for ~10% of all soft tissue sarcomas and commonly occurs in para-articular deep soft tissues of the extremities in young adults. [1] SS is a misnomer, the tumor originates not from the synovium, but from pleuripotent mesenchymal cells and is capable of partial or aberrant epithelial differentiation. [2] Less than 5% of SS occur in the head and neck region. The common sites in the head and neck region include hypopharynx, larynx, soft palate, tonsil, tongue, and infratemporal fossa. [3],[4] To the best of our knowledge, SS in intervertebral foramina of cervical spine has not been reported. We report a case of a poorly differentiated monophasic variant of SS in cervical spine mimicking a benign nerve sheath tumor. A 14-year-old boy presented with a history of pain in the right shoulder radiating to the right thumb and right index finger and weakness and wasting of right limb of 3-month duration. Magnetic resonance imaging (MRI) of cervical spine revealed a well-defined oval, lobulated, extramedullary mass lesion (1.2 × 3.1 × 1.5 cm) in C6-C7 intervertebral foramen. The lesion was extending from the right lateral aspect of spinal cord at C6-C7 level along the course of exiting nerve root at this level. The lesion was hyperintense on T2 weighted and hypointense on T1-weighted sequences [Figure - 1]a and b. There was widening of C6-C7 neural foramina [Figure - 1]c. No bone destruction was evident. There was no significant compression of the spinal cord. The tumor revealed intense homogeneous contrast enhancement [Figure - 1]d. Based on these MRI findings, a diagnosis of the benign nerve sheath tumor was made. At surgery, a well-defined epidural mass lesion was seen at C6-C7 level extending across the neural foramina. The tumor was completely excised. Microscopic examination of the excised specimen showed a nonencapsulated tumor, with irregular margins infiltrating the adjacent fibro-muscular soft tissue and surrounding few ganglion cells. Fascicles of long spindle tumor cells as well as sheets of small, round to oval cells were also seen [Figure - 2]a and b. These cells had scanty cytoplasm, coarse, granular nuclear chromatin, and small, inconspicuous nucleoli. No epithelial cells were seen. Mitotic activity was variable, with 5-10 mf/10 hpf. At places, a hemangiopericytomatous arrangement of tumor cells was seen [Figure - 2]c. Few nerve bundles were entrapped within the tumor. On immunostaining, the tumor cells were found to be diffusely positive for bcl2 and CD99, and focally positive for EMA [Figure - 2]d and e. S100P and CD34 markers were not expressed by the tumor cells. Ki67 (monoclonal MIB1) proliferative index was found to be high (40%) [Figure - 2]f. The FISH (Fluorescence in situ hybridization) SYT translocation/rearrangement test done on the paraffin-embedded tumor section, and revealed SYT translocation, t(X; 18) positivity with loss of normal copy of 18. The diagnosis was poorly differentiated monophasic variant of SS with high proliferative index. Postoperatively he had significant improvement in the right upper limb weakness. Metastatic workup was negative. Postoperative radiotherapy was advised to prevent local recurrence. However the patient's relatives denied any further treatment. At 6 months postsurgery, there were no signs of local recurrence or metastasis. SS usually presents as a well-defined heterogeneous mass which appears predominantly hyperintense on T2-weighted sequence. A triple signal intensity due to the presence of solid, cystic areas, fibrosis, and hemorrhage can be seen. [5] A heterogeneous intermediate intensity is usually seen on T1-weighted images. [6] Calcific foci may be present within the tumor which appears hypointense on T1- and T2-weighted images. [6] Adjacent bone destruction may be present. Regional lymphadenopathy may support the diagnosis of synovial sarcoma in the head and neck region. [2] They frequently reveal heterogeneous postcontrast enhancement. Smaller SSs, especially in the head and neck region, can be homogenously hyperintense on T2-weighted sequence and show homogeneous postcontrast enhancement. There have been few case reports of synovial sarcoma in the cervical spine region. [7],[8],[9] However, in these cases, a large heterogenous tumor with bone destruction and predominant paravertebral location were the prominent features. Cervical pain and swelling with or without upper arm weakness were the presenting symptoms. In our patient, the tumor was located in cervical intervertebral foramen with widening without any bone destruction. These features made us to think of the differential diagnosis of neurofibroma and schwanomma. Histologically SSs are divided into two subtypes, biphasic and monophasic, and biphasic variant is more common. The biphasic variant contains both epithelial and spindle cell elements and the monophasic variant contains only spindle cells, rarely epithelial or glandular cells. Poorly differentiated SSs are difficult to distinguish from other poorly differentiated mesenchymal sarcomas and primitive neuroectodermal tumors. Immunohistochemistry shows vimentin, EMA, bcl2, beta catenin, and CD 99 positivity. CD34 is consistently negative. The chromosomal translocation, t(X; 18) (p11.2; q11.2), is seen in more than 90% of SSs and this helps in confirming the diagnosis of SS. Predictors of poor prognosis include tumor size of more than 5 cm, older age, metastasis, and poorly differentiated morphology on histology. Complete surgical excision with negative surgical margins is the standard treatment. Radiotherapy can be given in those cases with large tumors of more than 5 cm and inadequate surgical margins. References
Copyright 2011 - Neurology India The following images related to this document are available:Photo images[ni11241f1.jpg] [ni11241f2.jpg] |
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