3,020 research outputs found
Desmoplastic primitive neuroectodermal tumor with divergent differentiation. Broadening the spectrum of desmoplastic infantile neuroepithelial tumors.
No full textAbstract
We report an unusual large, multicystic, posterior fossa neuroepithelial neoplasm involving the cerebellum, brain-stem, and quadrigeminal cistern of a 9-month-old girl. The neoplasm consisted of variably sized, sharply demarcated nests of small cells with a high nuclear-cytoplasmic ratio and moderately basophilic nuclei, embedded in a desmoplastic, immature-appearing, mesenchymal stroma. The nests contained mitoses but none were seen in the stroma. Glial fibrillary acidic protein (GFAP), neurofilament protein, synaptophysin, and cytokeratin (AE-1) were expressed in the nests. Mesenchymal cells were negative for neural markers but positive for vimentin and desmin. The neoplasm was interpreted as a mixed mesenchymal and primitive neuroectodermal tumor (PNET) with histologic features reminiscent of a recently described intraabdominal desmoplastic small cell tumor. The tumor responded poorly to chemotherapy and a second operation was performed 1 year later. The second specimen bore no resemblance to the original and consisted of epithelial-like nests and clusters of neoplastic cells frequently interrupted by sinusoidal vessels. Tumor cells had medium-sized vesicular nuclei with small nucleoli, and a granular cytoplasm. Occasional less cellular islands of neuropil-like tissue contained larger cells having eccentric, vesicular nuclei with prominent nucleoli and abundant pink cytoplasm. Mitoses were not conspicuous. Many cells expressed synaptophysin, neurofilament protein, and GFAP. Neurofilament protein was strongly positive in the larger, neuron-like cells and synaptophysin stained the neuropil-like areas strongly but was less prominent in the neuronal perikarya. Unexpectedly, the neuropil-like areas expressed epithelial membrane antigen, whereas the neuronal cells were negative for chromogranin A. The peculiar histologic picture, combination of phenotypic markers, and remarkable biologic behavior of this unusual tumor defies classification according to existing nomenclature and exemplifies the broad range of phenotypes expressed by primitive neuro-epithelial neoplasms
Prognostic factors in childhood ependymomas.
No full textBetween 1975 and 1989, 45 children with newly diagnosed intracranial ependymomas were treated at the authors' institution. Patients were managed with aggressive surgical resection, followed by postoperative CT or MRI scans to evaluate the extent of resection. Most patients received involved-field radiation therapy, however 10 were treated with craniospinal axis irradiation for disseminated disease, or malignant histology. Beginning in 1983, all patients were also treated with adjuvant chemotherapy with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), vincristine, and cisplatinum. Four patients died in the immediate postoperative period for an operative mortality of 8.8%. The 5-year progression-free survival for the remaining 41 patients was 36%. Tumor location had little effect on survival, as the 5-year PFS for supratentorial tumors was 26%, compared with 40% for the posterior fossa lesions (ns). Neither histologic degree of malignancy, nor use of adjuvant chemotherapy impacted on survival. The extent of surgical resection, as determined by operative reports and postoperative imaging studies, was a major determinant of outcome, as patients with total or near-total resections experienced a 5-year PFS of 60%, compared with 21% for children with partial resection or biopsy (p less than 0.01). It is concluded that the use of adjuvant chemotherapy with CCNU, vincristine, and cisplatinum does not improve progression-free survival in childhood ependymoma, and that the extent of surgical resection is a major determinant of outcome in this disease
Improved survival with the use of adjuvant chemotherapy in the treatment of medulloblastoma.
No full textBetween 1975 and 1989, 108 children with newly diagnosed medulloblastoma/primitive neuroectodermal tumor (MB/PNET) of the posterior fossa were treated at the authors' institution. The patients were managed uniformly, and treatment included aggressive surgical resections, postoperative staging evaluations for extent of disease, and craniospinal radiation therapy with a local boost. Beginning in 1983, children with MB/PNET were prospectively assigned to risk groups; those with "standard-risk" MB/PNET were treated with radiation therapy alone, while those in the "poor-risk" group received similar radiation therapy plus adjuvant chemotherapy with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), vincristine, and cisplatin. The 5-year actuarial disease-free survival rate for all patients treated between 1975 and 1982 was 68%, and 73% when patients who died within 2 weeks after operation were excluded. This survival rate was statistically better for patients treated after 1982 (82%) compared to those treated between 1975 and 1982 (49%) (p less than 0.004). There was no difference in disease-free survival rates over time for children with standard-risk factors; however, there was a significant difference in the 5-year survival rate for poor-risk patients treated prior to 1982 (35%) compared to those treated later (87%) (p less than 0.001). For the group as a whole, a younger age at diagnosis correlated with a poorer survival rate; however, this relationship between age and outcome was significant only for children treated before 1983 (p less than 0.001). These results demonstrated an encouraging survival rate for children with MB/PNET, especially those treated with aggressive surgical resection followed by both radiation therapy and chemotherapy. The results strongly suggest that chemotherapy has a role for some, and possibly all, children with MB/PNET
Choroid plexus carcinoma of childhood.
No full textThe presentation, growth patterns, and response to therapy of 11 consecutive children with choroid plexus carcinomas were analyzed, and the results were compared with the outcome reported in other series. Patients were a median of 26 months of age at diagnosis. Two patients had thalamic tumors, one had a posterior fossa primary, and the rest had ventricular lesions. Five of 11 (45%) children remain in continuous progression-free remission a median of 48 months from diagnosis. Four of the five in continuous remission had a "gross total" surgical resection, and only one received radiation therapy. Five of six patients with subtotal resections relapsed despite postoperative treatment with radiation therapy (three) and chemotherapy (one). The response to treatment with radiation therapy or chemotherapy at relapse was disappointing, with only one child (treated with etoposide) responding. In combination with other series, 11 of 14 children had prolonged progression-free survival after gross total resection (only two of whom received adjuvant therapy) compared with two of 20 after less than total resections, independent of the type of adjuvant therapy given. Adjuvant therapy for children with choroid plexus carcinomas is of unproven benefit, and this must be considered when analyzing innovative treatment trials for such children, especially for those with totally resected tumors. Patients with partially resected lesions fare poorly with present forms of treatment
Childhood meningiomas. Experience in the modern imaging era.
No full textTwenty children with meningiomas (ages 18 months to 17 years) received initial therapy at the Children's Hospital of Philadelphia between January 1975 and June 1991, accounting for 2% of children with primary brain tumors seen during that time interval. All were verified histopathologically, and none had had prior irradiation. Fifteen were male and 5 female. Fifteen tumors were intracranial, all located supratentorially. Two of these also had a component within the optic canal. One tumor was entirely within the orbit. Four meningiomas arose within the spinal canal. Associated conditions were neurofibromatosis (NF) type I (1 patient), NF type II (2 patients), and a facial alveolar rhabdomyosarcoma (1 patient). A gross total resection as documented by postoperative scan and operative note was accomplished in 12 patients. Four of these relapsed, at a mean of 3.5 years from initial surgery. In 4 patients a near-total resection (> 90%) was performed. Of these, 2 progressed at 9 months and 1.5 years. One of these died of complications associated with reoperation. In 4 patients a partial resection (50-90%) was performed. Two of these progressed at 4 months and 1 year, and the other 2 have been followed for less than 2 years. Five patients received radiation therapy (RT). One patient received RT as adjunctive therapy after primary surgery because of papillary histology. The other 4 had RT following reoperation for recurrence at a mean of 1.5 years from diagnosis (range, 7 months to 2 years). These 4 patients remain alive and with stable disease at a mean of 6 years from diagnosis (range 2-8.8 years).(ABSTRACT TRUNCATED AT 250 WORDS
Glial differentiation predicts poor clinical outcome in primitive neuroectodermal brain tumors.
No full textAbstract
Primitive neuroectodermal tumors (PNETs) of the central nervous system, including medulloblastomas (PNET/MB), are the most common malignant brain tumor of childhood. These tumors often express proteins characteristic of glial differentiation (glial fibrillary acidic protein, GFAP), neuronal differentiation (neurofilament proteins, NFPs), and/or photoreceptor differentiation (retinal-S antigen). To identify biological factors of prognostic significance in PNETs, the expression of glial, neuronal, or photoreceptor antigens was evaluated in the tumor specimens of 86 patients with PNETs by immunohistochemistry after microwave antigen enhancement. Patterns of differentiation were then compared with patient relapse-free survival. Multivariate analysis of PNET immunohistochemistry and clinical variables indicated GFAP expression conferred a 6.7-fold greater risk of relapse than tumors that did not express GFAP or NFPs. Increased risk of relapse was directly related to the amount of GFAP expression. Tumors exhibiting clumps or sheets of GFAP-staining cells were associated with a 3.0-fold increased risk of relapse compared with tumors that did not express GFAP, irrespective of immunohistochemical evidence of other differentiation, while scattered GFAP staining was not associated with increased risk of relapse. These findings indicate that expression of GFAP in PNETs has prognostic power comparable with the most significant clinical factors currently used to predict clinical outcome
Proton magnetic resonance spectroscopy of pediatric brain tumors.
No full textAbstract
1H magnetic resonance spectroscopy allows the regional quantitation of a number of metabolites from the brain in a noninvasive fashion. Spectra were obtained from 5 normal children and 25 children with brain tumors. Choline (Cho), N-acetylaspartate (NAA), creatine and phosphocreatine, and lactate were quantitated in the form of ratios. The brains of normal children showed relatively high concentrations of Cho and NAA and virtually no lactate, as has been shown in adults. Benign astrocytomas and ependymomas were characterized by an elevation of the Cho:NAA ratio and an abnormal accumulation of lactate. Intrinsic malignant tumors were remarkable for an even higher Cho:NAA ratio but had no more lactate than was found in the benign tumors. Proton magnetic resonance spectroscopy may prove useful in characterizing neoplastic tissue in conjunction with more conventional imaging modalities
Systematic and material independent variation of electrical, optical, and chemical properties of Ln-materials over the Ln-series (Ln=La,Ce,Pr,..,Lu)
No full textA model is presented that successfully predicts electro-optical properties of Lanthanide materials, irrespective whether these materials are inorganic or organic, diluted or concentrated, metallic, semi-conducting or insulating. The model is firmly based on recent experimental data revealing that the variation in 4f and 5d energies relative to the valence band over the Ln series (La, Ce, Pr,.. ,Lu) is universal. Application to LnS and the oxides LnO, Ln2O3 and LnO2 demonstrates its potential by correctly predicting the ground state electron configuration, metallic, insulating or semi-conducting behavior, Ln ion valence state and band-gap of these model Ln systems.Radiation, Radionuclides and ReactorsApplied Science
High-temperature X-ray diffraction measurements of fluorite-related rare earth antimonates Ln(3)SbO(7) (Ln = Nd, Tb) and their magnetic properties
No full textTernary rare-earth antimonates Ln(3)SbO(7) (Ln=rare earths) were prepared, and their structures were determined by X-ray diffraction measurements. They crystallize in an orthorhombic superstructure of cubic fluorite (space group Cmcm for Ln=La, Pr; Ccmm for Ln=Sm-Dy), in which Ln(3+) ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated). For Ln=Nd, two phases with the Cmcm and Cam space groups coexist at room temperature. When the temperature was increased, the Nd3SbO7 compound transformed into a single phase with the space group Cmcm. Through magnetic susceptibility measurements, an antiferromagnetic transition was observed at 3.0 K (Ln=Nd) and 7.8 K (Ln=Tb). Analysis of the magnetic specific heat for Tb3SbO7 indicates that the 8-coordinated Tb ions magnetically orders at 7.8 K, and with furthermore decreasing temperature, the 7-coordinated Tb ions shows antiferromagnetic ordering at 3.0 K
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