Guidelines
Syed M. R. Kabir and Adrian T. H. Casey
M.A. Hayat (ed.), Tumors of the Central Nervous System, Volume 6: Spinal Tumors (Part 1), Tumors of the Central Nervous System 6, DOI 10.1007/978-94-007-2866-0_4,
© Springer Science+Business Media B.V. 2012
Patwardhan et al. 2000 ) . The lipoma is therefore not a true neoplasm but rather a hamartoma or a malformation. This theory can explain why the lipoma is dorsally located and may also explain spinal lipoma without dysraphism (Ammerman et al. 1976 ; Dyck 1992 ; Lee et al. 1995 ; Matsui et al. 1997 ; Razack et al. 1998 ; Patwardhan et al. 2000 ; Kim et al. 2003 ) . The lipoma may contain peripheral nerve twig, dermoid cyst, skeletal muscles and lymphoid or renal tissue.
These originate from ectoderm or mesoderm (Ammerman et al. 1976 ; Timmer et al. 1996 ) . According to the “metaplasia theory”, connective tissue metaplasia leads to the deposition of fat within the dura (Ammerman et al. 1976 ; Matsui et al. 1997 ) . There is another hypothesis that postulates that adipocytes may arise from mesen- chymal cells. Under normal circumstances, mes- enchymal cells form spinal vessels and they are prevented from forming adipocyte by neural crest cells. However, this inhibition fails in the presence of defective neural crest cells and mesenchymal cells form adipocytes (Catala 1997 ; Kim et al.
2003 ) . Despite sharing some basic aspects; these theories do not fully explain the exact genesis of the spinal lipoma.
Clinical Presentation
Non-dysraphic intradural lipomas may present with local symptoms e.g. pain, or with features of mass effect once they are large enough (McGillicuddy et al. 1987 ) . Fifty-fi ve percent of all cases present in their second or third decades of life (Giuffre 1966 ) . Around 24% of patients present in their fi rst decade and 16% during the fi fth decade. The incidence is equal in both sexes (Fan et al. 1989 ) . Spinal lipomas may present as tetraplegia or fl oppy baby syndrome during the fi rst decade of life as a result of birth trauma to the spinal cord (Mori et al. 1986 ; Bhatoe et al.
2005 ) . In other cases, the manifestation may be delayed (Bhatoe et al. 2005 ) .The presentation is often with an ascending spastic paresis affecting one or both legs (Giuffre 1966 ; Iwatsuki 2006 ) . Pain when present is usually not radicular but
rather localized to the area involved (Giuffre 1966 ; Ammerman et al. 1976 ; Iwatsuki 2006 ) . Most patients are symptomatic for 2 years before seeking medical advice (Giuffre 1966 ; McGillicuddy et al. 1987 ) . However, in cases of lipomas restricted solely to the cervical spinal cord, over 80% of patients displayed symptoms for more than 10 years (Giuffre 1966 ) . The symp- toms are due to the lesions enlarging as a result of increased fat deposition in metabolically normal fat cells (Bhatoe et al. 2005 ) . These lesions gen- erally tend to be indolent in nature.
Location
Non-dysraphic intradural lipomas are com- monly found in the thoracic spine, followed by the cervico-dorsal region with only 12% in the cervical cord alone (Giuffre 1966 ; Lantos et al.
1987 ; Iwatsuki 2006 ) . They are characteristi- cally located in the posterior aspect of the cord within a small radius around the midline. They usually present to the surface (subpial) and dis- tort and expand the spinal cord (juxtamedul- lary). Most involve several spinal cord segments (Drapkin 1974 ) . True intramedullary lipoma is very rare with only a few cases reported in the literature.
Radiological Appearance
MR (Magnetic Resonance) imaging is the most sensitive modality for diagnosing intradural lipo- mas preoperatively (Bhatoe et al. 2005 ) . They have a short T1 relaxation time due to the high proportion of fat. As a result, there is character- istic hyperintense appearance on T1-weighted images (Fig. 4.1 ). This can be confi rmed with fat suppression images. Benign lipomas have relax- ation parameters similar to those of subcutane- ous fat. Liposarcomas and other fat-related tumors have longer T1 relaxation times and therefore are less intense than subcutaneous fat on T1-weighted images (Patwardhan et al. 2000 ; Blount and Elton 2001 )
Management Guidelines
Optimum management of these lesions remains controversial and there has been wide variation in their management. Interestingly, this range from conservative management with strict diet control to aggressive total removal of the lesion (Iwatsuki 2006 ) . The fat of the lipoma is metabolically sim- ilar to body fat. For this reason, some authors advocated weight loss and strict diet control.
Endoh et al. ( 1998 ) reported a case of an intra- dural lipoma in a 9 years old boy that shrank spontaneously with loss of general body fat.
Similar observations were also noted by
Akyuz et al. ( 2005 ) . However, this is not always the case as there has been reported cases in which rapid lipoma growth was observed despite scru- pulous diet control (Aoki 1990 ) .The surgical pit- falls in treating these lesions and the dangers of total removal has also long been recognized.
Elsberg ( 1925 ) , discussed the dangers of total removal of these lesions with the description of a disastrous post-operative quadriplegia. In Ammerman’s series (Ammerman et al. 1976 ) , the two patients who underwent laminectomy and total removal developed postoperative paraplegia.
The other fi ve patients who had a decompressive laminectomy with a biopsy or subtotal removal
Fig. 4.1 ( a , b ) Pre-operative and Fig. 4.1 . ( c , d ) Post- operative sagittal and axial MRI scan of the patient with cervical intradural lipoma showing characteristic high signal
on T1 weighted images. Note the presence of signifi cant residual tumour on the post-operative scans (From Kabir et al. ( 2010 ) . Reproduced with permission from Springer)
either improved or had minimal deterioration. In the series of 6 intramedullary lipomas described by Lee and Epstein et al. (Lee et al. 1995 ) , the patient who underwent 70% resection deterio- rated neurologically during the immediate post- operative period. In contrast, the patient who had 40% resection had neurological improvement post-operatively. Both these papers clearly show that the degree of resection is not directly related to postoperative clinical outcome. As the lesion is indolent in nature and because aggressive resec- tion is associated with signifi cant morbidity, many surgeons advocate doing a bony decom- pression and wide dural opening and no more than just a biopsy of the lesion (Elsberg 1925 ; Swanson and Barnett 1962 ; Foster 1966 ) . It is also
advocated that surgery should not be considered in asymptomatic patients (Dyck 1992 ) .
From our experience (Kabir et al. 2010 ) , good results can be obtained by avoiding aggressive debulking (Fig. 4.2 ). We advocate achieving a balance between the degree of decompression required and preservation of neurological struc- tures. Improvement of post-operative neurologi- cal status can be achieved despite the presence of signifi cant residual tumour (Kabir et al. 2010 ) . The main aim of surgery should, therefore, be decompression as the degree of resection does not necessarily correlate with the clinical outcome.
Following review of the literature and from our own experience, we propose a guideline for the management of these rare lesions (Fig. 4.3 ).
Fig. 4.2 ( a , b , c , d ) Intraoperative appearances of the same patient with the cervical lipoma following partial debulking. ( a , b ) Appearance following opening the dura.
Arrow pointing towards the spinal cord. ( c ) Part of the
lipoma that has been excised. ( d ) Tumour bed following debulking (From Kabir et al. ( 2010 ) . Reproduced with permission from Springer)
Suspected intradural lipoma
No Consider other
diagnosis
Any neurological symptoms/signs Bowel/bladder symptoms Worsening/intractable local symptoms
Consider surgery Aim of surgery:
-decompression with preservation of neural elements
-avoid aggressive debulking Conservative management
Weight loss if obese Regular clinical/radiological follow up
Regular post-operative clinical/radiological follow up Consider further surgery if neurological deterioration during follow up
Characteristic MRI
appearance Asymptomatic
Only local symptoms i.e. neck/back pain No neurological symptoms/signs
Fig. 4.3 Management guideline for the non-dysraphic intradural lipoma (From Kabir et al. ( 2010 ) . Reproduced with permission from Springer)
The main principles of our guidelines are as follows:
1. Asymptomatic patients, patients with local symptoms only e.g. pain and no neurological sign/symptoms can be managed conserva- tively with regular clinical and radiological monitoring,
2. In obese patients, weight loss should be considered
3. Any patient with worsening local symptoms i.e. worsening pain or any onset of neurologi- cal symptom or sign should be considered for surgery. This is because in these patients a point may have been reached when the spinal cord cannot accommodate any more and
there is no longer any physiological reserve.
Neurological dysfunction than rapidly mani- fests itself unless decompression is done (Lee et al. 1995 ) .
4. The aim of surgery should be decompression with preservation of neurological function.
5. The percentage of tumour debulked does not necessarily correlate with the clinical out- come. Good outcome has been reported with laminectomy and biopsy alone (Ammerman et al. 1976 ) .
6. Aggressive debulking should therefore not be attempted.
7. Duroplasty should be considered if primary dural closure without tension is not possible.
8. Further debulking may be considered if patients continue to deteriorate.
In conclusion, though non-dysraphic intra- dural lipomas are rare lesions, good surgical out- come can be achieved if certain principles are followed as outlined in this chapter.
References
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5
Abstract
Malignant spinal cord astrocytomas are uncommon neoplasms that typically manifest with the acute onset of symptoms such as pain accom- panied by motor and/or sensory disturbances. Most intramedullary spinal cord astrocytomas are low-grade, either diffuse WHO (World Health Organization) grade II, or less commonly, pilocytic astrocytomas (PA, grade I). Only 7.5% are diagnosed as high-grade astrocytomas, either anaplastic (AA, grade III) or glioblastoma (GBM, grade IV). Given the limited number of cases and often extremely small biopsies, there is no consensus regarding the prognostic signifi cance of AA compared to GBM.
In the largest retrospective study that stratifi ed these two histopathologic grades, Santi et al. (Cancer 98:554–561, 2003) were unable to detect a dif- ference in outcome. The authors acknowledge, however, that inadequate sampling may have biased the interpretation of the often tiny specimens.
Only age appeared to correlate with prognosis, with shorter survival reported in patients older than 40 years at the onset of disease. More recently, McGirt et al. (Neurosurgery 63:55–66, 2008) found that patients with nondisseminated AA treated with radical resection showed a trend towards increased survival. With respect to patients with GBM who under- went radical resection, the overall survival was only 9 months. Despite largely anecdotal indications that local control may be benefi cial, contro- versy persists regarding the prognostic value of the extent of resection.
Similar concerns have been voiced regarding the benefi ts of adjuvant
M. Santi (*)
Associate Professor of Pathology and Laboratory Medicine, University of Pennysylvania School of Medicine , Neuropathologist, The Children’s Hospital of Philadelphia , PA 19104, Philadelphia
e-mail: [email protected] E. J. Rushing
Universitäts Spital Zürich , Institut für Neuropathologie , Zürich 8091 , Switzerland