|Ahead of print
Infantile spinal extradural schwannoma: A rare occurrence
Batuk Diyora, Gagan Dhall, Mehool Patel, Kavin Devani, Rahul Chhajed, Ashish Dubey
Department of Neurosurgery, L.T.M.G. Hospital and L.T.M. Medical College, Sion West, Mumbai, Maharashtra, India
|Date of Submission||04-Apr-2021|
|Date of Decision||29-Jun-2021|
|Date of Acceptance||18-Jun-2021|
|Date of Web Publication||07-Jan-2022|
Department of Neurosurgery, L.T.M.G. Hospital and L.T.M. Medical College, Mumbai 400022, Maharashtra.
Source of Support: None, Conflict of Interest: None
| Abstract|| |
In comparison to spinal intradural and intradural–extradural schwannoma, purely extradural schwannoma is rare. There is no clearcut consensus about the origin of these tumors. There are very few cases reported in the pediatric population. On literature search, we have not found a similar case in the infantile age group. We report a case of purely spinal extradural schwannoma in a 5-month-male child who presented with paraparesis. Magnetic resonance imaging scan revealed a 7.5×2.5×1.2 cm size contrast-enhancing spinal extradural mass lesion extending from D4 to D10 vertebral level. The child underwent thoracic laminotomy, and the spinal extradural mass lesion was completely excised. Histopathological examination of the specimen revealed schwannoma. The child recovered well in the post-operative period. At 1 year follow-up, he has completely regained his power in both lower limbs.
Keywords: Extradural, infant, schwannoma, spinal tumor
| Introduction|| |
Spinal nerve sheath tumors can be intradural, intradural–extradural, purely extradural, and very rarely intramedullary., Literature is full of spinal intradural and intradural–extradural locations of the tumor. However, there is inadequate information regarding the purely spinal extradural schwannoma in terms of origin. These lesions are more common in female patients than in males and are more commonly located in the thoracic region. Duration of symptoms varies from few months to years, and most of these patients present with motor deficits due to the long tract’s compression. Pediatric extradural schwannoma is rare., We have not found a case of purely spinal epidural schwannoma in the infantile age group. We report a case of spinal extradural schwannoma in a 5-month-old infant who presented with paraparesis.
| Case Report|| |
A 5-month-child transferred from a pediatric unit with a complaint of restricted movements in both lower limbs. His mother has noticed that till the age of 4 months, baby was moving both lower limbs spontaneously. Slowly over a period of 1 month, there was a progressive decrease in both lower limb movements. The child was healthy, feeding well, and gaining weight. Neurological examination revealed normal power in both limbs, while spastic paraparesis was observed in both lower limbs. The child was crying on pinching both lower limbs. Hematological and biochemical parameters were normal. The child underwent magnetic resonance imaging (MRI) of the spine under general anesthesia. MRI scan of the thoracic spine revealed a 7.5 × 2.5 × 1.2 cm size spinal extradural mass lesion extending from D4 to D10 vertebral body level, which was homogeneous isointense on both T1-weighted [Figure 1]A and T2-weighted images [Figure 1]B and uniformly enhancing following intravenous gadolinium administration [Figure 1]C. The lesion was significantly compressing and pushing the spinal cord anteriorly. The lesion was entering into neural foramen on both sides at almost all levels. A significant portion of the lesion was entering into D7-8 foramen on the left side [Figure 2]A and B. The patient underwent excision of the spinal extradural mass lesion under general anesthesia in the prone position. Midline vertical incision was taken from D3 to D11 after confirming the spinal level based on the X-ray chest. Skin and subcutaneous tissue were cut open and subperiosteal dissection made. D2 to D11 spinous process processes and laminae exposed. D3 to D10 laminotomy done [Figure 3]A. Well-capsulated, firm, grayish-white extradural mass lesion was found from D3 to D10 level. Mass lesion was gently dissected out from the surrounding tissue. It was loosely adherent to spinal dura which was also separated out with a blunt dissector. At all the levels, a small part of the lesion extending into the neural foramina dissected out. At the D7–D8 level, a significant portion of the lesion was extending into the foramen, which was also excised with microsurgical techniques, and almost complete excision of the extradural lesion ensured [Figure 3]B. Spinal dura became lax and pulsations of the underlying cord were noticed. After ensuring adequate hemostasis, laminoplasty was performed. Wound was closed in layers. The post-operative course was uneventful. The patient slowly recovered in his neurology and took almost 6 months to improve in his lower limb power completely to normal.
|Figure 1: MRI of the thoracic spine (sagittal view) showing a 7.5 × 2.5 × 1.2 cm size contrast-enhancing spinal extradural mass lesion (C) extending from D4 to D10 vertebral body level, which is homogeneous isointense on both T1-weighted (A) and T2-weighted images (B). Lesion is significantly compressing and pushing the spinal cord anteriorly|
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|Figure 2: MRI of the thoracic spine (axial view) showing contrast-enhancing spinal extradural mass lesion with thoracic extension (B) at D8-9 level which appears isointense on T1-weighted images (A)|
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|Figure 3: Clinical photography showing laminotomy (A) and well-defined extradural mass lesion excised almost in one piece (B)|
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Histopathological examination revealed irregularly shaped parenchymal cysts surrounded by neural tumor tissue [Figure 4]A and evidenced by spindle cells in a loose myxoid background [Figure 4]B, with focal parallel arrangement of nuclei and nuclear palisading features suggestive of schwannoma.
|Figure 4: Photomicrograph showing schwannoma having intramural, irregularly shaped parenchymal cysts surrounded by neural tumor tissue (A) (4×) and evidenced by spindle cells in a loose myxoid background (B) (40×). Note the focal parallel arrangement of nuclei and nuclear palisading (H & E stain)|
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| Discussion|| |
Spinal epidural space is a potential dead space lying in the spinal canal and outside the dura matter and extending from the foramen magnum to the sacrum. It harbors epidural fat, veins, arteries, and nerves. Various benign and malignant lesions occupy this space, and due to proximity to spinal cords and nerve roots, they compress them. Spinal cord tumors constitute about 1–10% of all pediatric central nervous system tumors and childhood spinal schwannomas/neurofibromas account for 2.5–4% of all pediatric spinal tumors., They are commonly located in intradural extramedullary space. Pure extradural schwannoma is rare., Other uncommon location includes intraosseous and retroperitoneal., Childhood schwannoma is even rare and often associated with neurofibromatosis., As these lesions are often associated with neurofibromatosis, spinal tumors in patients with NF1 have excellent prognosis and less recurrence in comparison to NF2.
In comparison to intradural and intradural–extradural schwannoma, there is no clear information about origin of purely extradural schwannomas. Various hypotheses are being proposed about the origin of these tumors. They arise from the Schwan cells of very thin myelinated peripheral sensory and sympathetic nerve branches. This actually supplies the ventral and dorsal vertebral body, spinal dura, and nerve sheath. As they grow outside the thin perineurial sheath and destroy the delicate nerve, there is no clear evidence of tumor from the small nerve fiber., Therefore, these small epidural nerve fibers are the origin of extradural schwannoma, in which one cannot see the parent nerve during surgical exploration. Another hypothesis includes the origin of these tumors from multipotential mesenchymal cells or from displaced primitive neuroectoderm cells., Histopathologically, schwannoma has two different patterns: Antoni type A and Antoni type B. Type A tissue is more cellular and shows nuclear palisading and Verocay bodies. Verocay bodies are prominent extracellular matrix and result of secretion of laminin. Antoni type B is loosely organized tissue with myxomatous and cystic degenerative changes.
MRI plays a vital role in the evaluation of spinal epidural lesions. Because of its excellent soft-tissue contrast, MRI helps in the identification, extension, and characterization of lesions. Differential diagnosis of extradural spinal tumors in pediatric population includes various benign and malignant pathologies. Benign patholo gies include arachnoid cyst and paraganglioma. Malignant extradural spinal pathology comprises Ewing’s sarcoma, rhabdomyosarcoma, lymphoma, neuroblastoma, and acute myeloid leukemia.
Spinal cord compression is a medical emergency. In case of significant clinical symptoms, it requires urgent decompression. The surgical procedure aims to include urgent decompression, restoration or preservation of neurologic functions, and the reduction of skeletal deformities. Because of their extradural location, most of these tumors can be excised completely, bringing significant clinical improvement. This lesion is simple to resect and total resection of the tumor is recommended. Recurrence is not uncommon following partial resection of the tumor. In comparison to benign tumors, malignant tumors have poor neurological outcomes even after surgical decompression.
| Conclusion|| |
Purely spinal extradural schwannoma should be kept in the differential diagnosis of spinal extradural mass lesions, particularly in pediatric patients. These lesions can be completely excised without sacrificing the nerve root with good long-term clinical outcome.
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Conflicts of interest
The authors have no conflict of interest related to this manuscript.
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