Primary intraosseous malignant peripheral nerve sheath tumor of spine with a giant paraspinal and retrospinal subcutaneous extension
A 75-year-old male patient presented with rapidly progressive weakness of both lower limbs since past 3 months. At the time of presentation, he was bed ridden with grade 0 power in both lower limbs. Bladder involvement in form of urinary retention occurred 1 month back with patient on a indwelling Foley's catheter. There was a definite sensory level at L2 level for all modalities of sensation. Patient was known hypertensive and had ischemic heart disease with one episode of myocardial infarction and had undergone angioplasty 8 months back. Plain X-ray of lumbar region showed erosion of L3 vertebral body. Magnetic resonance imaging (MRI) pictures showed a large mass lying in paraspinal and retrospinal region []. The retrospinal extension was so massive that it almost extended to lie just beneath the skin. There was a small intraspinal component compressing the cord. L3 vertebral body was collapsed with tumor seen communicating into it. The intraspinal component extended outside only through one intervertebral foramen. However, the extraspinal component was seen extending several corresponding spinal levels from L1 to L4. The metastatic workup for the patient was negative. Another location of the tumor in the body could not be found out even after thorough work-up.\nA linear incision given on the back from L1 to L4 spine. The tumor was found to lie just beneath the skin []. The extraspinal part of the tumor was removed. The tumor was reddish brown, fleshy, vascular [] with infiltration into the surrounding tissue. L3 laminenctomy was performed and the intraspinal part excised. The tumor did not have any obvious connection with any nerve root or dura. There was no plane of demarcation between the tumor and the vertebral body. Vertebral body excision, grafting, and fusion procedures were not done because gross of co-morbidities with anesthetic risk.\nHistopathology showed densely cellular fascicles alternate with hypocellular myxoid zones []. The cellular areas showed large number of spindle cells arranged in a storiform pattern []. Each of the spindle cells have irregular contours with abundant eosinophilic cytoplasm and gross cellular atypia, mitotic figures, pleomorphism. Nuclei were wavy, buckled, comma shaped [] with prominent nucleoli [] suggestive of malignant variety of peripheral nerve sheath tumor. Histopathological evaluation was done by two independent pathologists and their impression were same. There were occasional areas of epithelioid differentiation and perivascular accentuation of tumor cells []. Negative glial fibrillary acidic protein (GFAP) immunohistochemistry ruled out astroglial origin []. Ki-67 proliferative index was 5.5%, suggestive of malignant nature of the tumor [].