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Schwannomatosis: A Case Report

B. Jaganath Kamath *, K.S.Manikandan**

* Professor
Department of Orthopaedics,  Kasturba Medical College, Mangalore.

Address for Correspondence:

Dr.B.Jaganath Kamath
Department of Orthopaedics,  Kasturba Medical College, Mangalore.


Schwannoma, also known as neurilemmoma, is a benign soft tissue tumour arising from the schwann cells of the nerve sheath. Schwannomas are usually solitary and encapsulated. Schwannomatosis is a recently recognized third form of neurofibromatosis that causes multiple schwannomas without vestibular tumors diagnostic of neurofibromatosis type 2. The authors are reporting a case of 33 year old male with multiple histologically proven schwannomas without radiological evidence of vestbular tumor and hence the diagnosis of Schwannomatosis.

J.Orthopaedics 2007;4(2)e37

Case Report:

A 33 year old male presented with history of swelling of the posteromedial aspect of left arm for the past three years. The swelling was initially painless to start with later it became painful. Pain was moderate in intensity with radiation to left hand along the lateral three fingers in the median nerve distribution. There was no history of hearing loss, giddiness or decreased vision. There was no history of recent trauma, fever or any constitutional symptoms. There was history of multiple swellings in the neck region, which was operated thrice within the past 13 years. The swellings were histologically proven to be neurilemmoma. Investigations in the past Ė Contrast enhanced CT Brain & Neck revealed no abnormality intracranially and the swelling in the neck had features suggestive of neurogenic tumor. Patient was not a diabetic nor any history suggestive of any chronic medical illness.

Fig.1 MRI shows soft tissue mass in the right carotid space

 There was a swelling on the posteromedial aspect of left arm of about 2 cm in diameter globular in shape, nonpulsatile, skin over the swelling was normal. On palpation, the swelling was tender to deep palpation, with no local rise of temperature, globular in shape, well defined, mobile in transverse direction with limited mobility in vertical direction and the swelling was nonreducible. There was tingling sensation in the median nerve distribution area on tapping the swelling. Shoulder, elbow and wrist movements were normal. There was no distal neurovascular deficit.

 Routine haematological investigations were within normal limits, haemoglobin-14.2gm%, total leucocyte count- 7,200, differential count-neutrophils-54%,  lymphocyte-36%, monocyte-8%, eosinophil-2%, erythrocyte sedimentation rate- 22mm in 1 st hour.

Magnetic resonance imaging of the arm showed well defined densely enhancing lesion measuring 18 x 17 mm noted in the left arm in the medial compartment adjacent to the brachial artery and vein- suggestive of schwannoma likely to be arising from the median nerve.

Fig.2. Sagittal T2 MRI of left arm showing Schwannoma

Provisional diagnosis of benign nerve sheath tumor was made. ( Schwannoma was considered based on previous histopathology report). It was decided to excise the mass. Intraoperatively the tumor was arising from the median nerve and was eccentric. The mass was not attached to the surrounding structures and was excised as a whole by careful intraneural fascicular dissection without damaging the nerve. Postoperatively there was minimal weakness of the median nerve distribution. Three months follow-up showed full recovery of the median nerve.

Fig.3. Shows intraoperative picture of the Schwannoma Fig.4. Shows excised tumor from the median nerve

Gross findings of the tissue mass revealed single nodular tissue, pale yellow in color measuring  3 x 1.5 x 1 cms. Outer surface is pale yellow covered by thin membrane, areas of hemorrhage seen. Cut surface pale yellow homogenous with specks of hemorrhage.

 Histopathological examination revealed an encapsulated tumor composed of spindle shaped cells arranged in fascicles with regimentation. Antoni A and Antoni B areas are seen. The cells are spindle shaped with elongated wavy nuclei, and abundant fibrillar cytoplasm, nuclei are degenerative and bizarre.


Fig.5. shows histopathology of Schwannoma with Antoni Aand Antoni B areas

Discussion :

Schwannoma (neurilemmoma) is one of the few truly encapsulated neoplasms of the human body and is almost always solitary. Itís most common locations are the flexor surfaces of the extremities, neck, mediastinum, posterior spinal roots, and cerebellopontine angle. The nerve of origin often can be demonstrated in the periphery, flattened along the capsule but not penetrating the substance of the tumor. Since this is a benign neoplasm every attempt should be made to preserve the nerve.

The Schwannoma (neurilemmoma) is the most common tumor of the peripheral nerve, it accounts for 8% of all primary intracranial tumors and 80-90% of those in the cerebellopontine angle. The peak incidence is in the third to sixth decades, with a slight female predominance. Intracranially there is a predilection for sensory nerves especially the vestibular branch of the eighth nerve. Rarely, schwannomas occur intraparenchymally within the brain, cerebellum, or spinal cord: in such rare instances, they presumably arise from schwann cells that accompany blood vessels.

Most schwannomas are single sporadic benign lesions. Bilateral vestibular schwannoma are the classic hallmark of neurofibromatosis type 2 (NF2), which predisposes to multiple schwannomas on cranial, spinal, and peripheral nerves and to intracranial and intraspinal meningiomas and intramedullary ependymomas. The term schwannomatosis or neurilemmomatosis has been used to describe patients with multiple nonvestibular schwannomas with no other signs of NF2. 

The microscopic appearance is distinctive. Two different patterns are recognized as Antoni A  and Antoni B areas. Antoni A areas are quite cellular and composed of spindle cells often arranged in a pallisading fashion or in an organoid arrangement (Verocay bodies). In type B areas, the tumor cells are separated by abundant fluid that may form cystic spaces.

Neurofibromas are distinct from schwannoma, these tumors are not encapsulated and have a softer consistency than schwannomas. In contrast to schwannomas, Verocay bodies, palisading of nuclei and hyaline thickening of vessel wall are almost always absent in neurofibromas.

Neurofibromatosis type I has features of multiple neurofibromas with a genetically determined disorder. It is an autosomal dominant disease; the responsible gene (NF1) is located near the centromere of chromosome 17.

Neurofibromatosis type II is characterized by bilateral vestibular schwannomas or in an individual who has first degree family  relative  with NF 2, is younger than 30 years of age, and presents with unilateral vestibular schwannoma or two of the follow                                                                      ing: meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacities and juvenile cortical cataracts. It results from alteration of a gene located in chromosome 22.

Schwannomatosis is a recently recognized third form of neurofibromatosis in addition to NF1 & NF 2.  The criteria for definite Schwannomatosis is two or more pathologically sampled schwannomatosis and lack of radiographic evidence of vestibular nerve tumor on an imaging study performed after age 18 years. The criteria for presumptive schwannomatosis is two or more pathologically sampled schwannomas without symptoms of eighth nerve dysfunction at age more than 30 years OR two or more pathologically sampled schwannomas in an anatomically limited distribution without symptoms of eighth nerve dysfunction at any age.  The proposed criteria for Schwannomatosis is age over 30 years and no evidence of vestibular tumor on high quality MRI scan, no known constitutional NF2 mutation and two or more non-intradermal (within or between layers of the skin) schwannomas, at least 1 with histologic confirmation Or One pathologically confirmed non-vestibular schwannoma plus a first-degree relative who meets above criteria.

The purpose of reporting this case is for the rarity of presentation of multiple nonvestibular schwannomas without any radiological evidence of intracranial tumor in a individual more than 30 years old and hence the diagnosis of schwannomatosis. The  importance in the patients with multiple schwannomas is to investigate radiologically for vestibular schwannomas and careful dissection of the mass preserving the underlying nerve.

Reference :

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  2. M.MacCollin; W.Woodfin; D.Kronn; and M.P.Short. Schwannomatosis: A clinical  and pathologic study. American Academy of Neurology 46: 1072-1079, 1996.

  3. Matti Tapio Seppala, Markku Alarik Sainio, Matti Jouko Johannes Haltia, JaakkoJyri Kinniunen, Kirsi Hannele Setala and Juha Erik Jaaskelainen. Multiple schwannomas: schwannomatosis or neurofibromatosis type 2?. J Neurosurg, 89, 36-41, 1998.

  4. Douglas C. Antony,  F.Stephen Vogel. Pherpheral nervous system. Andersonís Pathology. Tenth edition. Vol.2 page  2824-2826, 1996. 

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  6. Thomas R.Donner, Rand M. Voorhies, and David G. Kline. Neural sheath tumors of major nerves. J Neurosurg, 81:362-373, 1994.



This is a peer reviewed paper 

Please cite as : B.Jaganath Kamath : Schwannomatosis - A Case Report

J.Orthopaedics 2007;4(2)e37





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