|LETTER TO THE EDITOR
|Year : 2015 | Volume
| Issue : 4 | Page : 578-579
Malignant peripheral nerve sheath tumor of fourth ventricle and 7-8th cranial nerve complex: Case report
AA Wani1, M Laherwal1, AU Ramzan1, NK Malik1, I Lone2, FA Nizami1
1 Department of Neurosurgery, Sher-i- Kashmir Institute of Medical Sciences (SKIMS), Srinagar, Jammu and Kashmir, India
2 Departments of Pathology, Sher-i- Kashmir Institute of Medical Sciences (SKIMS), Srinagar, Jammu and Kashmir, India
|Date of Web Publication||10-Mar-2016|
A A Wani
Department of Neurosurgery, Sher-i- Kashmir Institute of Medical Sciences (SKIMS), Srinagar, Jammu and Kashmir
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Wani A A, Laherwal M, Ramzan A U, Malik N K, Lone I, Nizami F A. Malignant peripheral nerve sheath tumor of fourth ventricle and 7-8th cranial nerve complex: Case report. Indian J Cancer 2015;52:578-9
|How to cite this URL:|
Wani A A, Laherwal M, Ramzan A U, Malik N K, Lone I, Nizami F A. Malignant peripheral nerve sheath tumor of fourth ventricle and 7-8th cranial nerve complex: Case report. Indian J Cancer [serial online] 2015 [cited 2020 Jul 2];52:578-9. Available from: http://www.indianjcancer.com/text.asp?2015/52/4/578/178443
Malignant peripheral nerve sheath tumors (MPNSTs) are rare soft tissue sarcomas of ectomesenchymal origin, comprising 5% to 10% of all soft-tissue sarcomas, and often arise in anatomically discernible peripheral nerves or from neurofibromas. They have a strong association with NF1 and develop at a reported incidence rate of 1% to 29% in patients who have that disease. On the other hand, intracranial MPNST is rare, with only few intracerebral cases documented in the English-language literature ,, and two intra-cerebellar , cases documented so far. The terms malignant intra-cerebellar and intracerebral nerve sheath tumor is preferable to the term malignant intra-cerebellar and intracerebral schwannoma because schwannomas rarely undergo malignant change, and it is not clearly understood whether malignant intra-cerebellar and intra-cerebral nerve sheath tumors arise only from Schwann cells.
A 56-year-old person presented with tinnitus and decreased hearing on right side followed by gait disturbance. He had involvement of right 8, 9, 10 cranial nerves with right cerebellar signs. MRI was done, which revealed tumor involving fourth ventricle with extension in right cerebello-medullary cistern and right 7-8 complex. [Figure 1] The patient was operated by sub-occipital approach, and the portion of tumor which was in ventricle was removed, and the small portion along 7-8 complex was not removed. The tumor was moderately vascular, mostly suckable, and diffusively infiltrating the cerebellum. Intra-operatively, an external ventricular drain was inserted, which was continued in post-operative period. On first post-operative day, patient was neurologically intact except for gross ataxia and was bedridden due to it. Post-operative scan showed operative changes only [Figure 2]. Next day, patient developed deep vein thrombosis in left leg, which was confirmed on Doppler ultrasound, he was administered heparin 20,000 units per day in divided doses. On third day, he developed clinical features of pulmonary embolism and he died due to it. The histopathology revealed spindle-shaped cells with high mitotic activity and on immunohistochemistry, tumor was positive for S 100 [Figure 3]a and b].
|Figure 1: Contrast MRI showing tumor inside fourth ventricle and also involving 7-8th complex|
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|Figure 3: (a) Photomicrograph showing spindle-shaped cells with high mitotic activity (H and E X40). (b) IHE showing tumor positive for s100|
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Schwannomas within the neuraxis are rare and are more common in an intra-medullary than an intracerebral location. Intracerebral schwannoma occurs mostly in young adults (the mean patient age is approximately 25 years),, and that there is a slight male predominance,, whereas malignant intracerebral nerve sheath tumors often occurs in patients younger than 20 years and shows no male or female predominance. There is no racial association.
Malignant peripheral nerve sheath tumors arise from major or minor peripheral nerve branches, or sheaths of peripheral nerve fibers, and are derived from Schwann cells or pluripotent cells of neural crest origin. Arthur Purdy Stout (1885-1967) played a pivotal role in the development of current understanding of the pathogenesis of peripheral nerve sheath tumors by identifying the Schwann cell as the major contributor to the formation of benign as well as malignant neoplasms of the nerve sheath.
Theories regarding the origin of intra-medullary schwannomas have been proposed by several authors.,, The most generally accepted theory is that these tumors arise from proliferation of Schwann cells in the perivascular nerve plexuses. According to Riggs and Clary, hyperplasia of the perivascular nerve plexuses may be developmental or due to a chronic disease.
The great majority of MPNSTs occur in patients with NF1 with a cumulative lifetime risk of up to 10%. Only rarely do MPNSTs arise from malignant degeneration of a schwannoma, ganglioneuroma, or pheochromocytoma. Ten percent of these tumors occur in patients who have undergone radiation treatments for other disease processes, on average, 15 years after the initial treatments.
The diagnosis of these tumors remains problematic as it is based primarily on clinical suspicion. Rapid increase in the size of the mass or a rapid onset of symptoms should immediately alert the surgeon to the possibility of a malignant tumor. The gold standard for imaging of peripheral nerve tumors has become MR imaging. Magnetic resonance images can contribute useful pre-operative information concerning the suspected pathological entity. Unfortunately, whether a tumor is benign or malignant cannot be discerned definitively from the scan alone. Areas of hemorrhage or necrosis, heterogeneous enhancement, and cystic areas may suggest a malignancy, but are by no means definitive, and can occasionally be seen in benign tumors.
Once the diagnosis of MPNST is suspected, surgery is the mainstay of treatment., Although radiotherapy provides local control and may delay the onset of recurrence, it has little effect on long-term survival rates. There are reports, however, of routine post-operative radiotherapy and even radiotherapy as a single modality alone for MPNST in the literature., Like most soft tissue sarcomas, MPNSTs are traditionally chemotherapy insensitive. Chemotherapy for adult soft tissue sarcomas is usually confined to the treatment of metastatic disease.
The prognosis of patients with malignant PNST is poor unlike their benign counterparts; survival is reportedly influenced by tumor location, size, and association with NF1, and no significant correlation has been noted between survival and either grade or mitotic rate.
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[Figure 1], [Figure 2], [Figure 3]