bone tissue. It was very adherent to the right internal carotidartery and optic nerve, therefore, a subtotal excision was per-formed. On pathological examination, the lesion was composedof interconnecting osteoid islands and highly vascularized stroma.The osteoid tissue was rimmed by osteoblasts. Scattered osteo-clasts and small bony trabeculae were seen. There was no evi-dence of malignancy. The lesion was diagnosed as a benignosteoblastoma (Fig. 3).Post-operative neurological examination revealed no additional
deficit and there was no neurological progression over 18 years,other than the right eye lateral gaze palsy present preoperatively.There was no evidence of enlargement at 18 years on cranial CTscan and MRI (Figs. 4 and 5).
Benign osteoblastoma is a rare bone tumor with an indolent bio-logical behavior and good clinical prognosis. It is very rare inthe cranium.5 The temporal bone is the most common site of oste-oblastoma in the neocranium.6 In the reported case, the tumororiginated from the petrous temporal bone and extended to theparasellar region and cavernous sinus.It is important to differentiate osteoblastoma from osteoid oste-
oma. The pain from osteoid osteoma generally increases noctur-nally and responds to salicylates, while the pain fromosteoblastoma is continuous and does not respond to salicylates.Osteoblastoma has a greater potential to enlarge than osteoid oste-oma and presents by mass effect rather than pain.5,6 In this case,paralysis of the sixth cranial nerve aided localization of the pathol-ogy. Although imaging is insufficient to determine the nature ofthe lesion, it may be highly suggestive.2 However, low-gradechordoma, chondrosarcoma and giant cell tumors also have simi-lar radiological features.2 They present as cortical or medullary,diaphyseal or metaphyseal, prominently radiolucent lesions withvariable calcification and clearly defined, non-lobular margins.2
Histological diagnosis is important. On microscopic examination,early lesions contain actively propagated connective tissue isletsand older lesions frequently show large foci of ossification. Inall lesions, irregular fibrous stroma and osteoid deposits are seen.Stroma tends to be well vascularized, particularly in early tumorsand rarely exhibits extravasation. Rarely minor atypical changesmay be observed in osteoblast mitochondria.3
Optimal primary treatment of benign osteoblastoma is totalsurgical excision.7 If, as reported here, the tumor is not suitablefor total surgical excision due to its location, subtotal excision isadequate as the probability of recurrence is low. No progressionhas been observed during 18 years post-operative follow up inthis patient. Therefore, radical surgical excision, which may havesignificant post-operative morbidity and mortality, should beavoided and safer palliative excisions considered. If there isany evidence of malignancy on pathological examination, radio-therapy and chemotherapy may be administered. However, it hasbeen reported that radiotherapy may induce or promote malig-nant degeneration.1,2,3 Hence the role of the radiotherapy iscontroversial.
1. Batay F, Savas A, Ugur HC, Kanpolat Y. Benign osteoblastoma of the orbitalpart of the frontal bone: case report. Acta Neurochir 1998; 140: 729730.
2. Clutter DJ, Leopold LV. Benign osteoblastoma: report of a case and review ofthe literature. Arch Otolaryngol 1984; 110: 334336.
3. Lucas DR, Unni KK, McLeod RA, OConnor MI, Sim FH. Osteoblastoma:clinicopathologic study of 306 cases. Hum Pathol 1994; 25: 117134.
4. Berciano J, Perez JL, Fernandez F. Voluminous benign osteoblastoma of theskull. Surg Neurol 1983; 20: 383386.
5. Chen K, Weinberg R, Simpson P, Tschang T. Osteoblastoma of the nasal cavity.Laryngol Otol 1993; 107: 737739.
6. Khasaba A, Donata GD, Vassalo G. Benign osteoblastoma of the mastoid part ofthe temporal bone: case report. J Laryngol Otol 1995; 109: 565568.
7. Ciappetta P, Salvati M, Raco A, Artico M. Benign osteoblastoma of the sphenoidbone. Neurochirurgica 1991; 34: 97100.
Primitive supratentorialneuroectodermal tumor in anadult
AT Kouyialis1 MDMD, EI Boviatsis1 MDMD, IK Karampelas1 MDMD,
S Korfias1 MDMD, P Korkolopoulou2 MDMD, DE Sakas1 MDMD
1Department of Neurosurgery, University of Athens Medical School,
Evangelismos Hospital; 2Department of Pathology, University of Athens
Medical School; Athens, Greece
Summary We report the case of a 32-year-old female with a diag-
nosis of supratentorial tumour. Total removal of the tumour was
achieved in a two-stage procedure. Histopathology revealed a primi-
tive neuroectodermal tumour (PNET), an unusual and highly malig-
nant, mainly infratentorial tumour of childhood that is uncommonly
described in the supratentorial compartment of adults. We review the
literature and describe the existing knowledge of these tumours.
2005 Elsevier Ltd. All rights reserved.
Journal of Clinical Neuroscience (2005) 12(4), 492495
0967-5868/$ - see front matter 2005 Elsevier Ltd. All rights reserved.doi:10.1016/j.jocn.2004.07.014
Keywords: primitive neuroectodermal tumour, supratentorial,
Received 11 February 2004
Accepted 13 July 2004
Correspondence to: Efstathios J Boviatsis MD, Department of Neurosurgery,
Evangelismos General Hospital, 61 ipsilantou Street, Athens 115 21, Greece.
Tel.: +30 210 7201654; Fax: +30 210 7215281;
The term primitive neuroectodermal tumour (PNET) refers to agroup of neoplasms consisting of highly undifferentiated malignantcells that present mainly in children and histologically resemblecerebellar medulloblastoma. They are chiefly characterised bysmall, round, undifferentiated cells with scanty cytoplasm. Oneof the outstanding features of the malignant character of PNET istheir ability to disseminate within the central nervous system(CNS) via the cerebrospinal fluid (CSF) pathways. Thus, at the timeof diagnosis, multiple foci of disease are frequently discovered.Although this tumour is relatively uncommon, it is well
recognised, particularly in children, yet there is still ongoingdebate and considerable controversy concerning the histogenesisand classification of PNET. An extensive literature review hasrevealed few reports of PNET in adults.1 In this report, an adultfemale with a supratentorial PNET is described and the existingliterature regarding the unusual features of these tumoursreviewed.
Journal of Clinical Neuroscience (2005) 12(4) 2005 Elsevier Ltd. All rights reserved.
492 Kouyialis et al.
A 32-year-old woman was admitted complaining of severe morn-ing headaches, recent gait disturbance and fatigue with walkingdue to progressive decline in function of both lower limbs. Neuro-logical examination revealed increased tendon reflexes in theupper and lower limbs with normal muscle power. She had bilat-eral papilledema but no other neurological abnormality. CT andMRI of the brain revealed a large space-occupying lesion in themid- and parasagittal convexity of both hemispheres, just beneaththe calvarium (Fig. 1). The mass consists of three components; thelargest, measuring 5 7 7 cm, was directly under the bone;the other two sections, measuring 4 3 3 cm each, lay withinthe parenchyma, yet had clearly defined borders. Digital substrac-tion angiography (DSA) showed blood supply deriving frombranches of the left external carotid artery and a considerabledownward displacement of the superior sagittal sinus (Fig. 2).Due to the large size of the tumour, a two-stage procedure was
advised. The goal of the first procedure was to remove the centraltumour segment. This would allow the two smaller components toascend closer to the surface and enable better visualisation at thesecond stage, thus decreasing the risk of damage to eloquent areas.The first operation revealed that the tumour had extensively in-vaded and destroyed the overlying bone. This was removed untila healthy margin was reached. The central part of the tumour wasa whitish-grey colour, was highly vascular and friable and wastotally removed.Postoperatively, the patient had motor weakness on her left side
(2/5) that was treated conservatively with corticosteroids andphysical therapy and progressively recovered. Histopathologicalexamination showed neoplastic tissue consisting of a homogenouspopulation of small cells with deeply stained oval nuclei, scantycytoplasm and strongly positive for synaptophysin CD99 (Fig.3). The cells were growing within a fibrillary network and amongthem some larger cells with neuronal morphology were also iden-tified. The gross and microscopic morphology of the tissue and theresults of the immunocytochemical analysis were consistent withthe diagnosis of PNET with glial and cartilaginous differentiation.Due to propensity of PNET to metastasise via the CSF path-
ways, an MRI of the whole neuraxis with contrast enhancementwas obtained but no other lesion was demonstrated. The secondoperation was performed 4 months later in another hospital andcomplete tumour removal was achieved with no neurologic defi-cits. The patient refused irradiation or chemotherapy. She is cur-
rently under clinical and radiological follow up and 24 monthsafter the first operation there are no signs of recurrence.
Bailey and Cushing first reported PNET in 1924. They described aseries of 25 patients with tumours that seemed to arise from the4th ventricle and protrude into the cerebellum. Initially, theynamed this tumour cerebellar spongioblastoma. However, in1925, they extended their series to a total of 29 patients and re-named the tumour cerebellar medulloblastoma. Under this head-ing, low