Journal of Postgraduate Medicine
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Year : 1984  |  Volume : 30  |  Issue : 2  |  Page : 101-4  

Acoustic and spinal neurilemmomas : a study of vascular pattern.

SC Abhyankar, RR Vast, RB Trivedi, KP Deodhar 

Correspondence Address:
S C Abhyankar

How to cite this article:
Abhyankar S C, Vast R R, Trivedi R B, Deodhar K P. Acoustic and spinal neurilemmomas : a study of vascular pattern. J Postgrad Med 1984;30:101-4

How to cite this URL:
Abhyankar S C, Vast R R, Trivedi R B, Deodhar K P. Acoustic and spinal neurilemmomas : a study of vascular pattern. J Postgrad Med [serial online] 1984 [cited 2021 Oct 21 ];30:101-4
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Neurilemmomas are benign tumours of the nerve sheath. They can occur at any site, along the course of the nerve. Usually there is very little difficulty regarding their histological diagnosis.[1] On the trunk and extremities, they present merely as small swellings but when they occur along the intracranial or intraspinal nerves, they become clinically important. Most of the studies of these tumours are based on clinico-pathological correlation.[3] Although these tumours are benign, they show a wide range of alteration in their vascular pattern which may be reflected in the cerebrospinal fluid chemistry or their clinical presentation. Hence the study was undertaken to find out the vascular patterns of these tumours and to correlate their effects on the C.S.F. and other clinical data.


Thirty cases of neurilemmoma have been studied; 22 of these were from cerebellopontine angle and 8 were from the spinal cord. Their clinical presentation and C.S.F. findings were noted. All sections were stained with H & E and Verhoff's elastic Van Geison's stain. A minimum of three sections were studied from each tumour. Based on the vascular pattern, neurilemmomas were divided in the following groups: (1) those showing hyalinised blood vessels, (2) those showing angiomata, (3) those showing pallisading around the blood vessels and (4) those showing haemorrhage within the tumour.


The age and sex distribution is shown in [Table 1]. Occurrence of these tumours was common in the age group of 21-40 years. Female to male ratio was found to be 2:1.

Increase in C.S.F. proteins (more than 100 mg) was seen in 28 cases (93%). All tumours of the spinal nerves showed a rise in C.S.F. proteins and xanthochromia. Among 22 acoustic tumours only 5 were associated with xanthochromic C.S.F. [Table 1].

Blood vessels were either thin-walled or thick-walled. Their arrangement, whether evenly distributed or forming angiomata was noted [Table 2]. Haemorrhage in the tumour was extremely rare; but was considered to be primary because of rupture of blood vessels and not because of operative trauma, only when haemosiderin bearing macrophages and/or free haemosiderin pigment was observed in the vicinity of the haemorrhage.


Neurilemmomas are essentially benign tumours and seldom aquire malignant qualities.[2] Although they are benign, vascularity of these tumours may alter their behaviour and/or clinical presentation. Vascular arrangement in a neurilemmoma has a wide range. Majority of the tumours in our study showed increased vascularity which could be well correlated with the increase in the protein content of the cerebrospinal fluid. Rise it, C.S.F. proteins was seen in 28 cases, among which 18 were from cerebellopontine angle and 8 were from the spinal cord. This increase in C.S.F. proteins in cases of neurilemmomas is attributed to transudation of serum from abnormal vessels.[8]

Blood vessels were found to be arranged as clusters of thin or thick-walled channels, forming angiomata or scattered uniformly throughout the tumour. Angiomatas were observed in 10 cases. This angiomata formation in a neurilemmoma has been observed by Kasantikul et al[6] and they have called this tumour as a combined tumour.[4],[6] It has been proposed that ectomesenchyme, which is the source of these tumours, can get differentiated into neurilemmoma and angioma.[6] Out of 10 cases, 6 tumours showed thick blood vessel wall [Fig. 1] while 4 showed thin walled vessels [Fig. 2]. Thus it can be seen here that C.S.F. xanthochromia is more frequent in neurilemmomas containing thin-walled blood vessels. Sudden haemorrhage within the tumour associated with thin-walled blood vessels may cause acute raised intracranial pressure symptoms, especially in acoustic neurilemmomas.

Besides angiomata, hyalinization was seen in small and large blood vessels of the tumours in 10 cases. Hyalinisation was also observed within the tumour itself. These tumours did not show any evidence of haemorrhage within the Tumour. The dense collagen probably helps to prevent major haemorrhage in the tumour.[7]

Haemorrhage within the tumour was considered to be old only if the presence of haemosiderin laiden macrophages and/or free haemosiderin pigment was observed. Five cases of acoustic neurilemmoma showed evidence of old haemorrhage [Fig. 3] and the same cases showed xanthochromic C.S.F. Remaining 8 cases of xamthochromia were seen in spinal cord tumours which could be explained by blockade of C.S.F. circulation due to a spinal tumour.

Pallisading of tumour cells around blood vessels was observed in 4 cases [Fig. 4]. The presence of tumour cells surrounding the perivascular space and compressing the endothelial lining is a cause of haemorrhage in the neurilemmomas. Haemorrhage then may arise in these neoplasms not only because of rupture of thin-walled blood vessels but also from the neoplastic pressure and possible errosion of the endothelium by the neoplastic cells.[7]

Electron microscopic studies of these tumours by Kasantikul et al[7] have shown that thin-walled vessels in these neoplasms were lined by a single layer of endothelial cells and lacked any smooth muscle. The Junction between the endothelial cells was straight and patent. From these, R.B.C.s might have escaped into the neighbouring tumour tissue.

There was no correlation of vascularity of these tumours either with age, site or size of the tumour.

Thus, it appears from above study that vascular pattern of these tumours reflect C.S.F. chemistry and decides their tendency to bleed or otherwise. Especially in acoustic tumour if the C.S.F. is xanthochromic, it can be predicted that the tumour is likely to bleed more profusely during surgery than the one which is associated with C.S.F. showing only increase in proteins or a normal C.S.F. picture. In such cases, operating surgeon can take due precautions during surgery. Vascularity becomes also important in such tumours which have got tendency to bleed either within the tumour or in the subarachnoid space, which may be fatal.[5],[9]


We are most greatful to Dr. N. A. Dabholkar, Dean, L.T.M.M.C. & L.T.M.G.H. for allowing us to publish this work. We are also thankful to Dr. P. S. Ramani, Hon. Neurosurgeon for his clinical help and Mr. C. V. Desai, Artist for photomicrographs.


1Ackerman, 1. V. and Rosai, J.: "Surgical Pathology." Vol. 11, 6th Edition, The C. V. Mosby Company, Saint Louis, 1981, pp. 1555-1636.
2Ashley, D. J. B.: "Evan's Histopathological Appearances of Tumours". 3rd Edition, Churchill Livingston, Edinburgh, London and New York, 1978, pp. 440-505.
3Biswas, S. K., Sanyal, S., Roy, R. N. Sen Gupta, K. P.: A study on cerebellopontine angle tumours. Ind. J. Cancer, 13: 123-131, 1976.
4Folkman, J.: Tumour angiogenesis. Advances Cancer Res., 19: 331-358, 1974.
5Gleeson, R. K., Butzer, J. F. and Grin, O. D. Jr.: Acoustic neurinoma presenting as subarachnoid haemorrhage. J. Neurosurg., 49: 602-604, 1978.
6Kasantikul, V. and Netsky, M. G.: Combined neurilemmoma and angioma. Tumour of ectomesenchyme and a source of bleeding. J. Neurosurg., 50: 81-87, 1979.
7Kasantikul, V. and Netsky, M. G.: Light and electron microscopic observations of blood vessels in neurilemmoma. Arch. Path. &- Lab. Med., 103: 683-687, 1979.
8Long, D. M.: Vascular ultrastructure in human meningioma and schwannoma. J. Neurosurg., 38: 409-419, 1973.
9McCoyd, K., Barron, K. D. and Cassidy, R. J.: Acoustic neurinoma presenting as subarachnoid haemorrhage. A case report. J. Neurosurg., 41: 391-393, 1974.

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