Arq Neuropsiquiatr 2005;63(3-A):681-684

State University of Campinas (UNICAMP) Campinas SP, Brasil: 1Neurology and Neurosurgery Department; 2Radiology Department.

Received 15 October 2004, received in final form 27 December 2005. Accepted 14 March 2005.

Dr. Guilherme Borges - Rua Visconde do Rio Claro 322 - 13083-650 Campinas SP - Brasil. E-mail: guiborges@fcm.unicamp.br

IMAGING FEATURES AND TREATMENT OF ANINTRADURAL LUMBAR CYSTIC SCHWANNOMA

Guilherme Borges1, Leonardo Bonilha1, Marcílio Proa Jr.1, Yvens Barbosa Fernandes1,Ricardo Ramina1, Veronica Zanardi2, Jose Ribeiro Menezes2

ABSTRACT - Spinal schwannomas are frequently observed among patients treated in a reference neuro-s u rg e ry center. Cystic spinal schwannomas, however, are very scantly found. Due to its indolent behaviorand benign course, the diagnosis of schwannomas may pose a challenge to the care giver, and the imag-ing findings can be misleading. In this article, we illustrate an example of a pauci-symptomatic 55 year- o l dmale patient whose complaint was solely a non specific lumbar pain. Investigation revealed a large cysticlesion comprising the lower lumbar intradural space. He was then treated with micro n e u ro s u rgical tech-nique involving complete removal of the tumor and re c o n s t ruction of the duramater. Histological andimmunohystochemical diagnosis were consistent with cystic schwannoma. The patient presented with com-plete re c o v e ry of his symptom. In this article we aim to emphasize the clinical presentation and tre a t m e n tof lumbar spine schwannomas, and to illustrate the imaging findings within this uncommon case.

KEY WORDS: schwannoma, cystic tumor, nerve sheath tumor, neurinoma.

Achados imagenológicos e tratamento de um schwannoma cístico intradural lombar

RESUMO - O schwannoma cístico intra-espinal é tumor muito raro e poucos casos estão descritos na litera-tura: são usualmente assintomáticos e somente diagnosticados quando atingem grande tamanho causan-do compressão radicular. Com o intuito de ilustrar as armadilhas existentes re f e rentes ao diagnóstico etratamento desse tipo de tumor, nós relatamos um caso raro, focando nos passos da investigação e tera-pêutica. É descrito o caso de um paciente de 55 anos que apresentava apenas queixas de dor lombar. Ainvestigação revelou uma lesão cística extensa na região intradural lombar inferior. O tumor foi totalmenteressecado por técnica micro neurocirúrgica, sendo a dura-máter re c o n s t ruída. O diagnóstico patológico eimuno-histoquímico evidenciou tratar-se de um schwannoma cístico. Neste artigo, nós procuramos enfa-tizar as características clínicas e tratamento de schwannomas lombares, ilustrando os achados imagenológi-cos desse caso incomum.

PALAVRAS-CHAVE: schwannoma, tumor cístico, tumor de bainha nervosa, neurinoma.

Schwannomas are benign tumors of the periph-eral nervous system, arising from Schwann cells1.Schwannomas can occur virtually in any body loca-tion where peripheral or cranial nerves are pre s-e n t2, and they correspond to 8% of primary intra-cranial and 29% of primary spinal tumors1. Wi t h i nthe spinal region, Prevedello et al. have investi-gated the prevalence of diff e rent extramedullaryintradural spinal tumors and observed that schwa-nnomas comprised 66% of all cases3. The lumbarregion is one of the most common sites for occur-rence of spinal schwannomas, as demonstrated byConti et al., who studied the distribution of spinalschwannomas and re p o rted that 48% lie withinthe lumbar spine4. While schwannomas occurr i n gwithin the lumbar spine are not rare, large and

p redominantly cystic schwannomas occurring inthe lumbar spine have scantly been demonstrat-ed, even though it is well defined that benignschwannomas can eventually display degenerativechanges defined by cyst formation, calcification,h e m o rrhage and hyalinization1. Intere s t i n g l y, larg eschwannomas within the lumbar spine may gounnoticed for a large time span mainly due to theindolent growth of the tumor and the paucity ofsymptoms generated. With a more malleable stru c-t u re, a cystic schwannoma may pose a challengeto the diagnosis.

We present a rare case of a patient with a larg ecystic schwannoma in the lumbar region. We aimto emphasize the diff e rential diagnosis of cysticmasses of the intraspinal region by illustrating the

682 Arq Neuropsiquiatr 2005;63(3-A)

clinical picture, imaging findings and tre a t m e n tof this unique case. This re p o rt was approved bythe Committee of Ethics and Research of our Ins-titution (UNICAMP).

CASEA 55-year-old man without remarkable pre v i o u s

medical history was admitted in our Hospital due to a12-month history of lumbar pain with a poorly definedi rradiation to both lower limbs. His general physical exa-mination was normal and did not exhibit signs compat-ible with neuro f i b romatosis. His neurological physicalexamination failed to disclose signs of radicular irr i t a-tion, motor or sensory deficits. Magnetic resonance ima-ging (MRI) (Fig 1) depicted an extensive lesion (6.0x1.8x1.8 cm) extending from the 4th to 5th lumbar vertebraealmost completely constituted by a large cyst. Gadoli-nium contrasted MRI depicted a ring-like enhancementof the cyst. Tumor was totally removed by micro n e u ro-surgical technique (Fig 2). The remaining thin duramaterwas not large enough for primary repair, and an artifi-cial graft (DuraGenT M) was successfully used to accom-plish a water tight seal dura-mater closure. Histologicalexamination of the excised specimen revealed typicalschwannoma cell nuclei (Fig 3A). Immunohystochemicalstudy included staining for S-100 protein and NGFR(nerve growth factor receptor), which were both posi-tive diffusely across the tumor cells (Fig 3B and 3C). Theimmunohystochemical analysis alongside with the his-tological observations confirmed the diagnosis of a cys-tic schwannoma. After an unremarkable postoperativeperiod, the patient experienced a complete re m i s s i o nof preoperative symptoms. At a follow-up visit per-f o rmed 12 months after surg e ry, the patient was asymp-tomatic.

DISCUSSION

Schwannomas are slow growing benign tumors.They are usually encapsulated, and rarely under-go malignant transform a t i o n1. Schwannomas arisef rom the Schwann cells of the nerve sheath, andthey comprise the most common tumor type aff e c-ting the peripheral nerv e s1. The most common lo-cation of schwannomas are around peripheral ner-ves in the extradural space. Intracranial schwanno-mas have also been observed, and they usually ari-se from the facial, trigeminal, or vestibular ner-ves5,6. Conspicuously, schwannomas are more fre-quently observed in patients with neuro f i b ro m a t o-sis type 21, schwannomas can be observed in rather

Fig 1. Pre-operative sagittal MRI scan of the lumbar spine: In

A) T2-weighted image showing an intradural cystic lesion; In

B) T1-weighted image (gadolinium injection) showing the

enhanced thin ring-like cystic tumor capsule.

Fig 2. Intra-operative image show -

ing the cystic lesion after separa -

tion from the roots by blunt micro

dissection. A rootlet remains adher -

ent to the tumor disappearing

inside its capsule (arrow).

Arq Neuropsiquiatr 2005;63(3-A) 683

Fig 3. A) Hematoxylin-eosin study

of the histological section of the

excised tumor reveals typical

schwannoma cell nuclei. B) S-100

p rotein preparation of the histo -

logical section reveals intense

staining. C) Histological pre p a r a -

tion for investigation of NGFR

( n e rve growth factor re c e p t o r )

antigen shows intense positive

reaction.

r a re locations7. Women and men are equally aff e c t-ed by schwannomas1, and the literature is pro l i f-ic in showing cases of schwannomas affecting al a rge age range2, albeit there is a predefined pre d i-lection for occurrence in between the fourth tosixth decades of life1.

Benign schwannomas can occasionally displaydegenerative changes that are encompassed bycyst formation, calcifications, hemorrhage and hya-linization. When multiple degenerative changesa re encountered, schwannomas fit into the cate-g o ry of “ancient schwannomas”, which are extre-mely benign in course, rarely demanding any formof tre a t m e n t8. Specifically, the cystic degenerationof schwannomas occurring in isolation, i.e., with-out additional features of ancient schwannomas,is scantly encountered. Cystic degenerations havebeen observed in the orbital re g i o n9, in the olfac-tory groove10, in the tentorial hiatus and posteri-or cavernous sinus1 1, in the presacral re g i o n1 2 , 1 3,within the pancre a s1 4, in the maxillary sinus1 5, with-in the spinal cord1 6 - 1 8, and intraventricular1 9. Cysticschwannomas have also been observed surro u n d-ing cranial nerves such as the vestibular nerv e2 0,the vagus nerv e8 and within the jugular foramen2 1.Only seven cases of cystic lumbar nerve sheath tu-mors have been described in the literature point-ing out its resonance magnetic imaging pre s e n t a-tion22,23.

As schwannomas are benign tumors with a slowg rowth rate, the diagnosis of extracranial schwan-nomas my pose a challenge to the care giver whenfew symptoms are observed. In the case we re p o rt ,t h e re is a striking contrast with the paucity of sym-ptoms and the size of the tumor. This highlightsthe importance of suspecting of a cystic lumbarn e rve sheath tumor when symptoms associated tolumbar spinal cord, or nerve roots compression aree n c o u n t e red.More o v e r, schwannomas should beincluded in the diff e rential diagnosis of a cysticmass in the spinal region.

D i ff e rently from cystic calcified schwannomas,i.e., “ancient schwannomas”, cystic schwannomaspossibly behave in a similar fashion to solid sch-wannomas. There f o re, the treatment of a cysticschwannoma in that setting should involve radi-cal surgical excision of the tumor, which, as demon-strated in this case re p o rt, can be perf o rmed with-out inflicting any harm to the patient.

In conclusion, cystic schwannomas are rare be-nign tumors of the lumbar region. Clinical symp-

toms are usually due to the compression of lum-bar spine or nerve roots structures, but given theslow growth of the tumor, few symptoms can beo b s e rved up until the tumor has reached a larg emass. The treatment of cystic and non-calcifiedschwannomas involves safe radical excision of thelesion.

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