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PubMed1996

Cytogenetic analysis of a malignant triton tumor and a malignant peripheral nerve sheath tumor and a review of the literature.

Cytogenetic analyses of malignant peripheral nerve sheath tumors (MPNST) and malignant triton tumors (MTT) are few to date. Two separate triton tumor specimens from one patient and a MPNST specimen from another patient, both with peripheral neurofibromatosis (NF-1, von Recklinghausen disease), showed complex near-triploid complements and partial deletion of the short arm of chromosome 1. Notably, a structural abnormality of chromosome 17 was detected in the MPNST, and loss of chromosome 22 was detected in the MTT. The genes for peripheral neurofibromatosis (NF-1) and central neurofibromatosis (NF-2) have been mapped to these two chromosomes respectively.

Adolescent↗
PubMed1998

The effect of combined nicotinamide and carbogen treatments in human tumour xenografts: oxygenation and tumour control studies.

BACKGROUND AND PURPOSE: This was an investigation to study the effect of giving carbogen and nicotinamide (CON) on pO2 and the radiation response of human xenografted tumours. MATERIALS AND METHODS: The human xenografts were two sarcomas (ENE2 and ES3) and a glioblastoma (HTZ17). Nicotinamide (500 mg/ kg, i.p.) was administered 60 min before PO2 measurements and irradiation, while carbogen was given for 5 min before and during these treatments. Tumour pO2 was measured with an Eppendorf electrode and radiation response was assessed by local tumour control following irradiation with 10 daily fractions. RESULTS: All three xenografts were found to be poorly oxygenated (about 80% of all pO2 values were < or =2.5 mmHg). CON treatment improved the oxygenation status in all three tumours such that 65, 52 and 71% of the pO2 values were < or =2.5 mmHg in ENE2, ES3 and HTZ17, respectively. However, only in ES3 was this decrease significant. The TCD50 doses for all tumours were around 52-54 Gy. No significant improvement was seen with CON in ENE2 (TCD50 = 48 Gy) and HTZ17 (TCD50 = 56 Gy), but for the ES3 xenograft a significant decrease to 42 Gy was found. CONCLUSIONS: The three tumours used in this study appeared to show the same level of hypoxia as measured both by pO2 and radiation response. However, only one tumour showed a significant improvement after CON treatment, suggesting that not all hypoxic human tumours might benefit from this type of therapy.

Administration, Inhalation↗
PubMed1995

Neurogenic tumors of the mediastinum originated from the vagus nerve.

Thirty-nine patients with neurogenic tumors observed between 1974 to 1992 were reviewed. There were 32 patients with neurilemoma, one with neurofibroma, five with ganglioneuroma, and one with malignant neurilemoma. Two cases of neurilemoma originated from the vagus nerve, which is very rare. Surgical resection is recommended, not only to confirm the nature of the lesion, but also to prevent further growth and compression on adjacent structures. For benign encapsulated neurogenic tumors, resection is curative.

Ganglioneuroma↗
PubMed2000

Clinical report: contrast enhancement of tumor perfusion as a guidance for biopsy.

We describe three cases where biopsies from various tumors were guided by contrast enhancement of tumor perfusion. After i.v. administration of Levovist (Schering AG, Berlin, Germany), the tumors showed both hyper- and hypovascular areas. Biopsies from the latter showed marked necrosis or fibrosis. This may cause biopsies not being conclusive. To ensure fully diagnostic biopsies from irregular tumors we propose the biopsy to be performed from the most vascular part demonstrated by contrast enhancement.

Abdominal Neoplasms↗
PubMed1996

Surgical conditions of the cervical spine.

This article reviews the four most common surgical conditions of the cervical spinal cord other than vertebral fractures including atlantoaxial instability, cervical disc disease, caudal cervical spondylomyelopathy, and spinal cord tumors. Each disease is reviewed by signalment, history, neurological examination, differential diagnosis, pertinent diagnostic testing, treatment, postoperative care, and prognosis.

Animals↗
PubMed1998

Ras activation in astrocytomas and neurofibromas.

Oncogenic mutations resulting in activated Ras Guanosine Triphosphate (GTP) are prevalent in 30% of all human cancers, but not primary nervous system tumors. Several growth factors/receptors are implicated in the pathogenesis of malignant astrocytomas including epidermal growth factor (EGFR) and platelet derived growth factor (PDGF-R) receptors, plus the highly potent and specific angiogenic vascular endothelial growth factor (VEGF). A significant proportion of these tumors also express a truncated EGFR, which is constitutively activated. Our work demonstrates that the mitogenic signals from both the normal PDGF-R and EGFR and the truncated EGFR activate Ras. Inhibition of Ras by genetic or pharmacological strategies leads to decreased astrocytoma tumorgenic growth in vitro and decreased expression of VEGF. This suggests that these agents may be potentially important as novel anti-proliferative and anti-angiogenic therapies for human malignant astrocytomas. In contrast to astrocytomas, where increased levels of activated Ras GTP results from transmitted signals from activated growth factor receptors, the loss of neurofibromin is postulated to lead to functional up-regulation of the Ras pathway in neurofibromatosis-1(NF-1). We have demonstrated that NF-1 neurofibromas and neurogenic sarcomas, compared to non-NF-1 Schwannomas, have markedly elevated levels of activated Ras GTP. Increased Ras GTP was associated with increased tumor vascularity in the NF-1 neurogenic sarcomas, perhaps related to increased VEGF secretion. The role of Ras inhibitors as potential therapy in this tumor is also under study.

Astrocytoma↗
PubMed1999

Tumour oxygenation during fractionated radiotherapy--comparison with size-matched controls.

The effect of fractionated irradiation on the oxygenation status of experimental tumours was investigated using polarographic assessment of the pO2 distribution. Since an improvement in tumour oxygenation could simply be the result of tumour shrinkage, a comparison of pO2 readings of untreated size-matched control tumours was performed. Irradiation was carried out using 6 fractions of 6 Gy applied within 11 days. A comparison of polarographic pO2 data with size-matched untreated tumours revealed a significant improvement in oxygenation after the irradiation. The median pO2 was 0.9+/-0.1 mm Hg for unirradiated tumours at a volume of 180 mm3, while the corresponding data for irradiated tumours of comparable size were 2.3+/-0.5 mm Hg on day 21 and 4.8+/-0.9 mm Hg on day 28 after start of irradiation. From these results it can be concluded that the improvement of oxygenation after fractionated irradiation is not solely the result of a reduced tumour volume.

Animals↗
PubMed1998

Neoplasms with neural differentiation: a review. Part II: Malignant neoplasms.

Malignant peripheral nerve sheath tumors (MPNSTs) encompass a wide and unusual group of neoplasms with features of neural differentiation. They most commonly present as spindle cell neoplasms and it can be difficult to differentiate them from other spindle cell neoplasms such as leiomyosarcomas, fibrosarcomas and synovial sarcomas. Strict criteria need to be applied in order to make the diagnosis of MPNSTs. Helpful features include contiguity with a nerve or an association with von Recklinghausen disease. The use of immunohistochemical stains may also help to confirm the diagnosis. Markers such as S-100 protein, neurofilament, epithelial membrane antigen and Leu-7 (CD57) are frequently used to assess neural differentiation in these neoplasms. In addition to the spindle cell pattern, MPNSTs may also display an epithelioid pattern. Rarely, other elements may be seen including glands in the so-called glandular MPNST or muscle in triton tumors. In more unusual cases cartilage, adipose tissue and even bone are present. Also included in the group of MPNSTs are the peripheral neuroepithelial tumor, neurotropic or desmoplastic melanomas and malignant granular cell tumors. MPNSTs are highly aggressive tumors and should be treated accordingly.

Adult↗
PubMed2003

Intraparotid facial nerve neurofibromas.

OBJECTIVES: To provide an awareness of intraparotid facial nerve neurofibroma as a cause of parotid masses and to describe their characteristics and management considerations. STUDY DESIGN: Case report with literature review. METHODS: The medical records of three patients with intraparotid facial nerve neurofibromas are reviewed, and data concerning the patient's presentations, treatment, and disease course are presented with a review of the world's literature on intraparotid facial nerve neurofibromas. CONCLUSIONS: Tumors arising from the extratemporal course of the facial nerve are quite rare. The tumors arise from Schwann cells and include the schwannoma and the neurofibroma. The overwhelming benign nature of these lesions necessitates a conservative course of treatment. Histological diagnosis should be followed by a limited tumor excision with emphasis on retaining normal facial nerve function. Malignant lesions require wide excision with facial nerve grafting or facial nerve reanimation.

Adult↗
PubMed1998

Neurogenic sarcomas: experience at the University of Toronto.

OBJECTIVE: Elucidation of the natural history and optimal management of neurogenic sarcomas is not straightforward, because of diagnostic difficulties and the low incidence of this disease. The majority of neurogenic sarcomas are categorized and treated as soft tissue sarcomas, and only a few centers have sufficient experience to add to our understanding of these malignant tumors. This article proposes an algorithm for the management of these tumors. METHODS: A cohort of 18 cases of neurogenic sarcoma (overall mean follow-up period after oncological diagnosis, 33.7 mo), representing approximately 3% of all soft tissue sarcomas treated at the University of Toronto Musculoskeletal Oncology Unit (Toronto, Canada) between 1989 and 1995, were reviewed. The clinical and pathological criteria used to establish the diagnosis of neurogenic sarcoma, the presenting symptoms, the tumor size and grade, the ability to obtain tumor-free margins during en bloc resection, the time to recurrence, and the overall survival rates were noted. A centralized pathological review of the biopsy was undertaken in all cases. RESULTS: A metastatic survey demonstrated localized disease for 16 of the 18 patients. The overall management strategy for these 16 neurogenic sarcomas with localized disease was to obtain local control by en bloc resection. Tumor size, tumor grade, and, most importantly, the ability to obtain tumor-free margins were all relevant prognostic factors for survival. Tumor-free surgical margins were obtained for 11 of 16 patients, with 9 of these 11 patients remaining disease-free. In contrast, all patients for whom tumor-free margins could not ultimately be achieved died as a result of their disease. CONCLUSION: Based on our experience, we propose an algorithm for the management of these rare tumors, for both optimal patient care and oncological research.

Adolescent↗
PubMed2002

Effectiveness of radical resections in malignant dumbbell tumors of the thoracic spine: review of three cases.

We report postoperative evolution and prognosis after radical resection of three dumbbell-shaped neurogenic tumors. It was a malignant schwannoma in all cases. Patients were observed from 8 to 27 months postoperatively. All tumors were completely excised, with histologically controlled extratumoral resection limits. The surgical technique used is the one developed by the authors for extended Pancoast Tobias resections. The patients had been operated on previously with possible local contamination, and the previous surgical wound needed to be excised with the tumor The patients died 8, 12, and 27 months postoperatively. This short series of three malignant dumbbell tumors dramatically shows that prognosis is undoubtedly more related to inadequate previous resection and to the tumor malignancy than to the surgical technique itself. The authors consider that the combined anteroposterior approach is the most efficient technique with minimum complications, even in major multilevel resections. Indications for such extended surgery include the inability to use adjuvant therapy and impending neurologic deficit.

Adult↗
PubMed2003

A comparison study of staging systems for bone sarcomas.

A retrospective study of 250 patients treated at one institution was done to evaluate the prognostic significance of the new American Joint Committee on Cancer staging system compared with the Musculoskeletal Tumor Society staging system for patients with sarcomas of bone. Regarding the Musculoskeletal Tumor Society system, there were significant differences in survival among patients with Stage I, Stage II, and Stage III disease. There were no significant differences between patients with Stages I-A and I-B disease, nor between patients with Stages II-A and II-B disease. Similarly, regarding the new American Joint Committee on Cancer staging system, there were significant differences among patients with Stage I, Stage II, and Stage IV disease. No significant differences were seen between patients with Stages I-A and I-B disease, between patients with Stages II-A and II-B disease, nor between patients with Stages IV-A and IV-B disease. A significant advantage in the ability to predict prognosis for one staging system over the other staging system was not shown with the relatively small number of patients in this study.

Ameloblastoma↗