- Department of Neurosurgery, Taichung Veterans General Hospital, Taichung, Taiwan, R.O.C.
- Department of Radiology, Taichung Veterans General Hospital, Taichung, Taiwan, R.O.C.
Department of Neurosurgery, Taichung Veterans General Hospital, Taichung, Taiwan, R.O.C.
DOI:184Copyright: © 2014 Pan S. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Pan S, Cheng Y, Kao T. Intramedullary melanotic schwannoma: Case report and review of the literature. Surg Neurol Int 16-Jul-2014;5:
How to cite this URL: Pan S, Cheng Y, Kao T. Intramedullary melanotic schwannoma: Case report and review of the literature. Surg Neurol Int 16-Jul-2014;5:. Available from: http://sni.wpengine.com/surgicalint_articles/intramedullary-melanotic-schwannoma-case-report-and-review-of-the-literature/
Background:Intramedullary melanotic schwannomas are very rare. Only seven cases have been previously reported. This is the first reported case of such a tumor presenting with intratumoral hemorrhage closely mimicking a hemorrhagic ependymoma.
Case Description:A 23-year-old female patient presented with progressive right lower extremity pain and numbness for 3 months and this was followed by acute paraparesis and urinary incontinence. Physical examination revealed sensory and motor dysfunction below T4 level. Magnetic resonance imaging of her spine showed a heterogeneous signal lesion occupying the intramedullary space with small foci of hyperintensity on T1WI and hypointensity on T2WI at the T4-5 level. She underwent emergent surgical decompression and microsurgical excision of the tumor. A histopathological diagnosis of melanotic schwannoma was made. Postoperative neurological recovery revealed progressive improvement in her examination findings.
Conclusion:Among spinal cord neoplasms, melanotic schwannomas are extremely rare tumors. The similar source of Schwann cells and melanocytes, the neuroectoderm, has been suggested to be the origin of melanotic schwannomas. Intramedullary melanotic schwannomas presenting with hemorrhage tend to be mistaken with ependymoma, which by far is the most common spinal tumor to present with hemorrhage. Total surgical excision if safely possible is currently considered the ideal treatment of choice.
Keywords: Intramedullary schwannomas, intramedullary tumor, melanotic schwannomas, schwannomas imaging features
Melanotic schwannoma is a nerve sheath tumor composed of melanin-producing cells with ultrastructural features of Schwann cells. The tumors occurred predominately in an intradural extramedullary location present at a younger age than conventional schwannomas. Intramedullary melanotic schwannomas are very rare. Only seven cases have been reported in literature.[
A 23-year-old female patient without any significant medical or genetic history had been suffering from progressive right lower limb numbness and soreness with pain for 3 months. She acutely deteriorated developing progressive paraparesis with urinary incontinence days before being brought to our hospital. Her physical examination revealed sensory impairment with pathological reflexes below the T4 level. Muscle power of bilateral lower extremities was Grade 2. A magnetic resonance imaging (MRI) study was undertaken immediately after examination and revealed an intramedullary heterogeneous enhanced lesion at T4-5 level [
Preoperative MR images. ((a) T1WI, (b) T2WI, (c) Postcontrast T1WI). A heterogeneous intramedullary enhanced lesion at T4-5 level with small foci of hyperintensity on T1WI (arrow) and hypointensity on T2WI. Hemosiderin deposition within tumor mass indicated previous hemorrhagic episodes. Long segment of syringomyelia was also noted
In view of her acute and progressive neurological decline and the MRI findings suggesting a focal well defined intramedullary tumor, we decided to operate on her emergently. We performed laminectomies from lower T3 to upper T6 level. The dura was opened in midline and kept by tenting suture. The tumor was intradural intramedullary and was visualized on the surface of the dorsal cord. The tumor appeared to be dark black in color and appeared to have a plane demarcating the tumor from adjacent normal cord parenchyma. En bloc tumor resection was performed after devascularization carefully. Different stages of hemorrhage were visualized and resected. Intraoperative histopathology revealed a preliminary report of a melanin-rich low-grade neoplasm with Ki-67 of 5%. A surgical gross total resection was confirmed by postoperative MRI scans [
Grossly, the tumor was heavily pigmented and almost entirely grayish-black tissue. The surgical specimen showed demarcated borders and ovoid shaped with rubbery consistency. Hematoxylin and eosin staining revealed that the tumor had been composed of both bland-looking epithelioid and spindle tumor cells containing melanin pigment and focal grooved nucleus. The tumor appeared to infiltrate nerve fascicles, which was accompanied by a large sized blood vessel. Immunohistochemistry was positive for diffuse Human Melanoma Black-45 (HMB-45), melan-A, vimentin, and S-100 [
Morphological appearance along with immunohistochemical profile of melanotic schwannoma. Photomicrograph showing tumor composed of both bland-looking epithelioid and spindle tumor cells containing melanin pigment and focal grooved nucleus, proliferation of astrocytes with eosinophilic body and Rosenthal fibers formation (a,b). Immunohistochemistry was shown to have diffuse immunocoloration for melan-A (c) and S-100 (d)
Schwannomas constitute 30% of primary spinal neoplasms and occur predominately in intradural extramedullary locations associated with ventral or dorsal nerve roots. Melanotic schwannomas are uncommon tumors. Since its first reported appearance in 1932, only about 100 cases have been reported in the related literature.[
Melanotic schwannoma is less common in the spinal canal. Most of the spinal melanotic schwannomas are located in the thoracic region. These tumors can grow extradurally or intramedullary. Only seven cases of intramedullary melanotic schwannoma have been previously reported.[
A detailed review of the related literature, including intramedullary melanotic schwannoma presentation, duration of symptoms, location, treatment, and outcome, are illustrated in
Surgical excision is treatment of choice in most cases. In seven operative cases, six did not show recurrence, whereas one showed aggressiveness and contiguous invasion requiring radiotherapy, re-operation, and carboplatin chemotherapy. Our patient presented acute deterioration of neurologic deficit and recovered well after early surgical decompression of the spinal cord compromise. She showed a nearly complete recovery and has been recurrence free over the last 3 years of follow-up. Our report is the first Asian case and the youngest one, also the only case with tumor hemorrhage. It remains unknown at this time if there is any relative factor between race and tumor bleeding risk.
Intramedullary melanotic schwannomas are extremely rare. Intramedullary melanotic schwannomas presenting with hemorrhage tend to be mistaken with ependymoma, which by far is the most common spinal tumor to present with hemorrhage. The theory that the tumor may originate from the rostral components of the neural tube is still compatible with our patient. Total surgical resection is the best treatment. Further genetics study and follow up are expected.
1. Culhaci N, Dikicioglu E, Meteoglu I, Boylu S. Multiple melanotic schwannoma. Ann Diagn Pathol. 2003. 7: 254-8
2. Font RL, Truong LD. Melanotic schwannoma of soft tissues. Electron-microscopic observations and review of literature. Am J Surg Pathol. 1984. 8: 129-38
3. Hoover JM, Bledsoe JM, Giannini C, Krauss WE. Intramedullary melanotic schwannoma. Rare Tumors. 2012. 4: e3-
4. Killeen RM, Davy CL, Bauserman SC. Melanocytic schwannoma. Cancer. 1988. 62: 174-83
5. Mandybur TI. Melanotic nerve sheath tumors. J Neurosurg. 1974. 41: 187-92
6. Murali R, Field AS, McKenzie PR, McLeod DJ, Stretch JR, Thompson JF. Melanotic schwannoma mimicking metastatic pigmented melanoma: A pitfall in cytological diagnosis. Pathology. 2010. 42: 287-9
7. Vezzosi D, Vignaux O, Dupin N, Bertherat J. Carney complex: Clinical and genetic 2010 update. Ann Endocrinol (Paris). 2010. 71: 486-93