Schwann cells harbor the somatic NF1 mutation in neurofibromas: evidence of two different Schwann cell subpopulations.

Neurofibromas are one of the most characteristic features of neurofibromatosis type 1 (NF1), an inherited autosomal-dominant neurogenetic disorder affecting 1 in 3500 individuals worldwide. These benign tumors mainly consist of Schwann cells (SCs) and fibroblasts. Recent evidence demonstrates that somatic mutations at the NF1 gene are found in neurofibromas, but it has not been demonstrated whether SCs, fibroblasts and/or both cell types bear a somatic loss of NF1. We recently established a cell culture system that allows selective expansion of human SCs from neurofibromas. We cultured pure populations of SCs and fibroblasts derived from 10 neurofibromas with characterized NF1 mutations and found that SCs but not fibroblasts harbored a somatic mutation at the NF1 locus in all studied tumors. Furthermore, by culturing neurofibroma-derived SCs under different in vitro conditions we were able to obtain two genetically distinct SC subpopulations: NF1(-/-) and NF1(+/-). These data strongly support the idea that NF1 mutations in SCs, but not in fibroblasts, correlate to neurofibroma formation and demonstrate that only a portion of SCs in neurofibromas have mutations in both NF1 alleles.

Long-term culture and characterization of human neurofibroma-derived Schwann cells.

Neurofibromas are benign tumors arising from the peripheral nerve sheath and are a typical finding in neurofibromatosis type 1 (NF1). Schwann cells are the predominant cell type in neurofibromas and thus are supposed to play a major role in the pathogenesis of these tumors. It is not known, however, if NF1 mutations in Schwann cells result in an altered phenotype that subsequently leads to tumor formation. To characterize the biological properties of neurofibroma-derived Schwann cells we developed cell culture techniques that enabled us to isolate Schwann cells from neurofibromas and grow them in vitro for several weeks without significant fibroblast contamination. Neurofibroma-derived Schwann cells were characterized by altered morphology, heterogeneous growth behavior, and increased expression of the P0 antigen while several other features of normal human Schwann cells were retained. We conclude that neurofibroma-derived Schwann cells exhibit a distinct phenotype in vitro but that the observed abnormalities by themselves are insufficient to explain neurofibroma formation. Application of our improved culture conditions makes neurofibroma-derived Schwann cells readily available for further studies to define their role in tumorigenesis in neurofibromatosis type 1.

Multiple intracranial juvenile xanthogranulomas. Case report.

The authors report on an 11-year-old boy in whom proptosis of the eye caused by a benign intraosseous xanthofibroma of the left orbital wall became clinically apparent at the age of 4 years. Two years later he developed bilateral papilledema, at which time computerized tomography and magnetic resonance studies revealed multiple enhancing intracranial lesions. The largest mass was located in the left middle fossa; other lesions were located at the tentorium cerebelli, in both lateral ventricles, near the superior sagittal sinus, and extracranially near the left jugular vein. The mass in the left middle fossa was resected and diagnosed as juvenile xanthogranuloma (JXG). Thirty months later, the patient again became symptomatic, exhibiting behavioral abnormalities and a decrease in mental powers. At that time, the two remaining lesions in both lateral ventricles had grown enough to cause trapping of the temporal horns and raised intracranial pressure. These lesions were successively resected and histopathologically confirmed to be JXGs. However, resection of the second intraventricular lesion was complicated by postoperative bilateral amaurosis, presumably caused by postdecompression optic neuropathy. According to a review of the literature, fewer than 20 patients with JXG involving the central nervous system have been reported. The patient described in this report is the first in whom multiple intracranial JXGs developed in the absence of cutaneous manifestations. Although JXGs are biologically benign lesions, the treatment of patients with multifocal and/or progressive intracranial manifestations is problematic.

Multiple symmetric lipomatosis: an unusual cause of childhood obesity and mental retardation.

Multiple symmetric lipomatosis (MSL), also known as Launois-Bensaude syndrome or Madelung's disease, is a rare disorder predominantly seen in middle-aged male patients. The disorder is characterized by large subcutaneous fat masses distributed around the neck, shoulders, and other parts of the trunk, often associated with nervous system abnormalities. A close relationship to alcoholism, metabolic disturbances and malignant tumours has been observed. Until now, MSL has only been described in adults. We report on the first two children, a 9-year-old girl and a 13-year-old boy, with the characteristic clinical findings of MSL. The girl presented with severe obesity, developmental delay, mild mental retardation, peripheral neuropathy, and latent hypothyroidism. In addition, she had elevated lactate concentrations in blood and cerebral spinal fluid suggesting mitochondrial dysfunction. Biochemical analyses of muscle showed a respiratory chain complex II deficiency. The boy suffered from severe obesity, mild mental retardation and insulin resistant diabetes mellitus. In both children, analyses of the mitochondrial genome did not reveal major deletions nor the MERRF 8344 point mutation. MSL seems to be a new neurometabolic disorder with heterogeneous clinical expression whose pathogenesis is still unknown.

Interdisciplinary treatment in pediatric patients with malignant CNS tumors.

Despite sophisticated surgical methods only a few pediatric CNS tumors can be controlled by operation alone. Therefore multimodality treatment regimens are needed to improve quality of life and survival, which is most important in malignant neoplasms. Since 1998 we have treated 16 children with malignant CNS tumors. All 16 patients have been treated on an interdisciplinary basis and are therefore accompanied by a pediatric neurooncology group consisting of a neurosurgeon, pediatric oncologist, and radiotherapist. Depending on tumor histology, child's age, and extent of surgery, further adjuvant therapy is planned by this group. Newly diagnosed tumors are typically treated by a specific chemotherapy protocol according to a multi-institutional study. In recurrent tumors more individual treatment regimens are considered. Data concerning surgery, adjunctive treatment, complications, and outcome of all patients and four case reports are presented.

CT and MRI of congenital sinonasal ossifying fibroma.

We report a 9-year-old boy with a sinonasal ossifying fibroma, probably congenital, with atypical findings on CT and MRI. CT revealed a soft-tissue density mass in the sphenoethmoidal sinuses, nasal cavity and right maxillary sinus with a few foci of calcification and with remodelling and destruction of the adjacent facial bones. MRI showed high signal on T2- and intermediate signal on T1-weighted images. A thin, partly enhancing outer shell and some nonenhancing septa were visible on contrast-enhanced images. MRI also showed the tumour to extend into the anterior cranial fossa. Subtotal removal was performed. We compare our findings with reports in the literature and discuss the differences from fibrous dysplasia.

MRI abnormalities in neurofibromatosis type 1 (NF1): a study of men and mice.

Hyperintense lesions on T2-weighted MR images of the brain, predominantly located in the basal ganglia, the brainstem and cerebellum, are a frequent finding in patients with neurofibromatosis type 1. Nature and significance of these lesions are still unknown so that the term 'unidentified bright objects' (UBOs) has been introduced to allow an unbiased description. We analyzed brain MRI scans of 31 children with definite diagnosis of neurofibromatosis type 1 according to the NIH criteria. High-intensity lesions on T2-weighted images were present in 86% of the patients. They did not correlate to other MRI findings such as optic pathway gliomas and were not indicative of intellectual impairment. Additionally, brain MR imaging of Nf1 knockout mice was performed to find out if similar abnormalities are present in this animal model. A total of 9 Nf1 knockout mice was examined on a dedicated animal MRI scanner at 4.7 Tesla but no evidence of high-signal intensity lesions on T2-weighted images was found. Therefore, the Nf1 mouse model seems to be unhelpful in providing further insights into the histological basis of hyperintense MRI abnormalities in NF1 patients.

A new leukoencephalopathy with bilateral anterior temporal lobe cysts.

We describe an identical syndrome of cystic leukoencephalopathy in three Turkish children, including two siblings. The neurological findings were noted within the first months of life and include severe intellectual impairment, motor retardation, and spasticity. Magnetic resonance imaging of the brain showed extensive cysts within the anterior temporal lobes, ventricular enlargement and white matter disease. The signal intensities of the cysts' content were identical to those of the cerebrospinal fluid. The patients' screening for known inborn errors of metabolism, especially those characterised by white matter involvement, did not reveal any abnormality. The clinical picture and the magnetic resonance imaging characteristics are unique diagnostic features of a new disease entity so far not described in the literature.

Cerebellar mutism syndrome.

Since 1980, a growing number of pediatric patients with mutism following posterior fossa surgery have been recognized. This syndrome typically affects children and in rare cases young adults who become mute one or two days after tumor operation but do not show disturbances of consciousness or language comprehension. The disorder persists for 1 to 4 months. The pathogenesis is still unknown. Of 21 children who underwent surgery for large posterior fossa tumors between 1991 and 1995, 6 developed cerebellar mutism. Histologically the tumors were classified as astrocytoma WHO grade I, astrocytoma WHO grade II and ependymoma WHO grade III in one case and medulloblastoma WHO grade IV in three cases. Besides the clinical course, intraoperative findings and CT or MRI data are evaluated and discussed considering possible etiological hypotheses. Our own experience and also literature reviews suggest that the lesion of the cerebellar hemispheres might be the most important one of multiple factors causing cerebellar mutism. Generally the syndrome is transient. The diagnosis should not delay adjuvant therapy in patients with a malignancy.

Paraneoplastic limbic encephalitis in two teenage girls.

Paraneoplastic neurological disorders represent remote effects of cancer without invasion of tumor cells into the nervous system. Limbic encephalitis is a distinct entity mostly associated with small-cell carcinoma of the lung. We present the cases of two teenage girls who were admitted with clinical symptoms typical for limbic encephalitis. In the course of the disease, they exhibited characteristic evolutionary changes of brain MRI abnormalities. Onset of neurological symptoms and type of underlying neoplasia were different in both patients. In one girl the initial workup led to the diagnosis of nodular sclerosing Hodgkin disease which so far had not caused any symptoms besides the described neurological abnormalities. A diagnostic brain biopsy showed inflammatory changes and excluded invasion of malignant cells into the central nervous system. The other patient had been diagnosed with a small cell carcinoma of the ovary several months before neurological and brain MRI abnormalities were observed. This is the first report in which clinical picture, evolution of MRI abnormalities, and--in one case--characteristic neuropathological changes are suggestive of paraneoplastic limbic encephalitis in two adolescent girls.

Combined therapy of medulloblastoma: review of 46 patients treated in a single institution.

Medulloblastoma is the most frequent malignant brain tumor in pediatric patients. Early treatment strategies, combining surgery and radiotherapy alone, resulted in survival rates of about 40% only. In the last 15 years, chemotherapy was used more frequently in combination with surgery and radiotherapy. The rationale was to increase the survival rate and to decrease radiation toxicity in young children. Forty-six patients younger than 16 years were treated between July 1977 and September 1995 in our institution (32 boys and 14 girls). Thirty-nine patients could be evaluated according to their postoperative treatment with regard to different protocols such as SIOP 1, SIOP 2, HDMTX/VCR, HIT protocol 89/91 and Carbo-PEI (one patient). In total, 21/39 patients are alive without evidence of disease (EFS 55 +/- 7%) with a follow-up of 26 to 210 months. Four children are lost to follow-up. Twelve patients died after relapse, 1 child died of MTX-induced brain atrophy, 1 patient developed a secondary malignancy (acute lymphoblastic leukemia) and died. The best results were seen in patients treated according to the HIT 89/91 protocol as first-line treatment (CR 9/10). The improvement in outcome of our patients with medulloblastoma in recent years suggests the benefit of intensified chemotherapy on survival. In addition, refinement in surgical and radiological treatment have certainly also contributed to the better results.

Primitive neuroectodermal tumors of the cerebral hemispheres in two siblings with TP53 germline mutation.

AWe report on two siblings (brother and sister) who developed cerebral PNETs at the age of 5 years and 6 months, respectively. Both children were treated by operation followed by polychemotherapy. The brother also received cranio-spinal irradiation. Nevertheless, the children died about 12 months and 24 months post-operatively due to extensive cerebral tumor recurrences. Shortly after having lost both of her children, the mother developed an intra-abdominal tumor, which was resected and histologically diagnosed as ovarian carcinoma. Because of this unusual familial clustering of tumors and a positive history of brain tumors and other cancers in several maternal relatives, we analyzed DNA isolated from both PNETs and the ovarian carcinoma as well as constitutional (leukocyte) DNA from the whole family for mutation of the TP53 tumor suppressor gene. This analysis revealed that all tumors were homozygous for a missense mutation at codon 213 (CGA => TGG) resulting in an amino acid exchange from arginine to tryptophane. The same mutation was present in one TP53 allele in the constitutional DNA of the mother and the children, indicating that the mother had transmitted a TP53 germline mutation to both of her children. Analysis of loss of heterozygosity at microsatellite markers from 17p confirmed deletion of the paternal (wild-type) allele in both PNETs. Further investigation of the PNETs by comparative genomic hybridization revealed multiple chromosomal abnormalities. Interestingly, some genomic changes were common to both PNETs, while many others were not, a finding suggesting substantial genomic instability, probably as a consequence of p53 inactivation.

Clinical and genetic aspects of X-linked adrenoleukodystrophy.

X-linked adrenoleukodystrophy (ALD), a leukodystrophy characterized by abnormal accumulation of saturated very long chain fatty acids in brain white matter and adrenal cortex, is the most common inherited peroxisomal disorder. The biochemical defect is localized to the level of lignoceroyl-CoA synthesis, a step in the peroxisomal beta-oxidation of very long chain fatty acids. The responsible gene encodes a peroxisomal integral membrane protein of as yet unknown function which is a member of the ATP-binding cassette transporter protein superfamily. The patient gene mutations are heterogeneously distributed over the functional protein domains with a tendency to clustering in the nucleotide-binding fold. The mechanisms by which these mutations cause a loss of protein function is unknown. Diagnosis of patients and carriers, including prenatal testing, is mainly based on the clinical picture, the demonstration of increased levels of saturated very long chain fatty acids in tissues and body fluids as well as on DNA mutation analyses. There are at least six distinct clinical phenotypes ranging from the severe childhood cerebral form to asymptomatic persons. The various phenotypes commonly occur within the same kindred. Modifying genes and/or environmental factors may contribute to this phenomenon. At present, there is no proven therapy for the prevention or cure of the neurological disabilities. Several approaches are under investigation including diets, immunosuppression, bone marrow transplantation and gene therapy.

Complete remission of a diffuse pontine glioma.

A patient is described in whom a large diffuse glioma of the pons extending into the midbrain was diagnosed at the age of 2 years. Biopsy showed a fibrillary astrocytoma. After shunting of a hydrocephalus, the clinical symptoms abated without conventional therapy. Repeated MRI studies showed a continuous decrease of the tumour which was no longer visible when the patient was 6.6 years old. In reviews on spontaneous remissions of oncologic disorders we were unable to find a case of a biologically benign brain stem tumour. There is one isolated report on a similar case, though without histologic documentation.

Gianotti-Crosti syndrome associated with Epstein-Barr virus infection.

Gianotti-Crosti syndrome (GCS) is a distinct exanthematic, acrolocated eruption of childhood caused by a variety of infectious agents. Historically hepatitis B antigen positive (HBsAG+) papular acrodermatitis of childhood and HBsAg negative (HBsAg-) papulovesicular acrolocated syndrome have been distinguished. Here we characterize the spectrum of associated infectious agents in seven patients with confirmed GCS seen in our departments in the years 1994-1995. Where available, stored frozen serum samples were reanalyzed for antiviral antibodies. The mean age of the two girls and five boys was 22.5 months with a range of 8 to 53 months. None of the patients was HBsAG+. Four patients showed serologic evidence of an acute infection and one patient of a recent Epstein-Barr virus (EBV) infection. In two additional children vaccination preceded the appearance of GCS. In these two patients serologic investigations revealed no evidence of recent infection with most common viruses. Our results underline the role of viral infections other than hepatitis B in the etiology of GCS. EBV infection was the most commonly associated viral disease in our population. We agree with other authors that we should avoid using the terms papular acrodermatitis of childhood and papulovesicular acrolocated syndrome in describing HBsAg+ and HBsAg- forms of GCS.

Goldenhar, Möbius and hypoglossia-hypodactyly anomalies in a patient: syndrome or association?

UNLABELLED: The Möbius, Goldenhar and hypoglossia-hypodactyly anomalies are usually sporadic conditions with a recurrence risk of about 2%. The combination of Goldenhar and one or the two others is rare, whereas the concomitant occurrence of Möbius and hypoglossia-hypodactyly, and/or Poland, and/or Klippel-Feil anomaly is well known. Pathogenetically, vascular disruptions around the 4th embryonic week have been hypothesized. In vivo and pathological studies as well as animal models support this theory for all the above-mentioned combinations. Whether a preceding blastogenetic alteration is an influencing factor or a disorganization mutation, remains unclear. We describe a 3-year-old girl with bilateral anotia, epidermoid on the right eye, 6th and 7th nerve palsy, hypoglossia, left hypodactyly, and ventricular septal defect. CONCLUSION: We wish to emphasize the aetiological relevance of vascular disruptions in this previously unreported combination of Möbius, Goldenhar and hypoglossia-hypodactyly anomalies. The concurrence of anomalies in this patient represents an association and not a pleiotropic syndrome.

Papillon-Lefèvre syndrome--successful treatment with a combination of retinoid and concurrent systematic periodontal therapy: case reports.

Papillon-Lefevre syndrome is a rare autosomal-recessive congenital differentiation disorder; the external signs are hyperkeratosis of the palms and soles. Intraorally, the most salient manifestations are dystrophic periodontal problems that affect both the primary and permanent dentitions and frequently lead to premature tooth loss. Two children were treated with acitretin 0.5 mg/kg of body weight per day from November 1992 to November 1993, and another child since October 1993. Concurrently, the children received professional oral hygiene care (scaling, root planing, and curettage). The combination of retinoid therapy and periodontal treatment improved the dermatologic and periodontal conditions.

Intracranial germ cell tumors: a comprehensive update of the European data.

Intracranial germ cell tumors are rare tumor entities in childhood and adolescents. Extra- and intracranial germ cell tumors are identical in their histologic pattern and occur in preferential midline localizations such as the pineal and the suprasellar region. Germ cell neoplasms show increasing incidence rates over the last 30 years. The majority of intracranial germ cell neoplasms are germinomas. About 90% of the patients with pure germinomas can be salvaged by radiotherapy alone according to modern protocols. Non-germinomatous malignant CNS-germ cell tumors are considered to have a poor prognosis. In order to improve the survival of patients affected by these tumors different treatment approaches adding chemotherapy to conventional surgery and radiotherapy have been initiated by various study groups throughout the world. Due to the rarity of these neoplasms only a very limited number of patients has been enrolled in each study. In 1993 an international working group on these tumors was established by the International Society of Pediatric Oncology (SIOP).