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|Year : 2015 | Volume
| Issue : 4 | Page : 634-635
Malignant peripheral nerve sheath tumor arising in a skull-vault defect
Abdulkhader Shehna1, Paul V Puthussery2, Sivaramakrishnan Ramesh3, Firosh Khan4
1 Department of Radiotherapy and Oncology, Thrissur, Kerala, India
2 Department of Radiodiagnosis, Government Medical College, Thrissur, Kerala, India
3 Department of Neurosurgery, Jubilee Mission Medical College Hospital, Thrissur, Kerala, India
4 Department of Neurology, Mother Hospital, Thrissur, Kerala, India
|Date of Web Publication||4-Aug-2015|
Department of Neurology, Mother Hospital, Thrissur - 680 012, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Shehna A, Puthussery PV, Ramesh S, Khan F. Malignant peripheral nerve sheath tumor arising in a skull-vault defect. Neurol India 2015;63:634-5
An 18-year-old male with a congenital bony defect of the right parietal region (possibly due to an enlarged parietal foramina)  presented with swelling of the same region for 6 months [Figure 1]a. Examination revealed an 8 cm × 8 cm soft nontender swelling without any neurological deficits. Computed tomography [Figure 1]b-d and magnetic resonance imaging [Figure 1]e-i scans of the brain showed a soft tissue density lesion containing enhancing and cystic areas and foci of hemorrhage. The standard metastatic workup was negative. The tumor, which was seen between the dura and scalp, was dissected out through a right temporoparietal craniotomy. Macroscopic examination showed a gray-brown friable tumor with blackish areas and no dural invasion. Microscopic examination [Figure 1]j and k showed plump spindle cells with oval nuclei and interspersed abundant vascular channels. The tumor cells showed an indistinct eosinophilic cytoplasm and pleomorphic hyperchromatic nuclei. Many bizarre cells and multinucleate giant cells were seen. Immunohistochemistry (IHC) revealed a strong vimentin and S100 positivity, CD34 patchy positivity and smooth muscle actin (SMA), desmin, cytokeratin, epithelial membrane antigen (EMA), glial fibrillary acidic protein (GFAP), HMB45, and CD31 negativity [Figure 1]l and m.
|Figure 1: (a) Photograph of tumor in the right parietal region; (b) axial plain computed tomography (CT) bone - window showing defect in right parietal bone with smooth sclerotic margins; (c) CT scan brain - window showing a lobulated soft tissue lesion (with hemorrhagic areas) at the bone defect with intracranial and extracranial extension; (d) postcontrast CT showing enhancing and necrotic foci; (e) magnetic resonance imaging scan axial T1WI; and, (f) fluid - attenuated inversion recovery image revealing the bone defect; (g) gradient - echo image showing hemorrhage as blooming; (h) sagittal T2WI showing the lesion in association with the bone defect; (i) postcontrast coronal T1WI showing heterogeneous enhancement with necrotic areas. Note the mass effect on adjacent brain and enhancement along adjacent dura (dural tail); (j) H and E stain section showing fusiform and spindly tumor cells with pleomorphic hyperchromatic nuclei; (k) spindle cells with elongated nuclei arranged in fascicles and dilated vascular spaces with staghorn appearance; (l) immunohistochemistry showing strong S100 positivity of tumor cells; and, (m) diffuse and strong positivity of vimentin|
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The histopathological examination (HPE) was suggestive of a malignant spindle cell mesenchymal tumor. Malignant peripheral nerve sheath tumor (MPNST) was considered in view of S100 positivity along with arrangement of spindle cells in sheets.  CD34 patchy positivity and EMA negativity are not against the diagnosis; and, vimentin positivity may be nonspecific and may not negate the diagnosis.  A similar histopathological examination and immunohistochemistry (IHC) is possible with a malignant melanoma also.  However, HMB45 was negative, thus excluding this diagnosis. Anaplastic meningioma with sarcomatous change can have a lobulated radiological appearance, spindle cell histopathological pattern and vimentin positivity in IHC.  However, the intact dura along with EMA and cytokeratin negativity are pointers against this diagnosis. EMA is supposed to be a very sensitive marker for a meningioma.  A mesenchymal chondrosarcoma was also considered, but thought to be less likely since there were no well differentiated cartilagenous areas and the tumor cells were positive for S100.
MPNST usually arise from skull-base; one arising in skull-vault is being reported for the first time. Our case is unique since the tumor developed at the region of a congenital bony defect. The role of this altered anatomy in triggering the tumor development needs to be debated.
| » Acknowledgment|| |
We would like to acknowledge the help of Dr. Lekha K. Nair MD, Department of Pathology, Amala Medical College Thrissur, Kerala, India.
| » References|| |
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