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Objective: The most frequent intracranial appearance in children with neurofibromatosis type 1 (NF1) is represented by the presence of hyperintense lesions on T2-weighted images, the so-called "unidentified bright objects" (UBOs). Di Paolo demonstrated that these lesions represent foci of myelin vacuolization with increased water content. The aim of this study was to investigate the isotropic apparent diffusion coefficient (ADC) values within the UBOs and normal-appearing brain and at the regressed UBO sites., Methods: Fifteen consecutive children with NF1 underwent magnetic resonance diffusion evaluation of the brain. Fifteen healthy age- and sex-matched children constituted the control group. Apparent diffusion coefficient maps were obtained, and regions of interest were placed bilaterally in 8 different areas. Two cortical areas were evaluated using single-pixel analysis. Apparent diffusion coefficient values within the UBOs were calculated by using irregular regions of interest. Regressed UBO sites were investigated by using circular regions of interest. Apparent diffusion coefficient values within the different areas were compared using a t test., Results: Compared with the controls, NF1 patients showed higher ADC values (P < 0.001) in all locations. In the NF1 group, the mean ADC value in the UBOs was higher than in other locations (P < 0.001). The mean ADC value within the regressed UBO sites was higher than in the normal-appearing locations (P < 0.001)., Conclusions: The higher ADC values in children with NF1 suggest an increase in water content of the normal-appearing brain. The UBOs are the areas with the highest water content. The regressed UBOs sites show higher water content than the normal-appearing areas.

Plexiform neurofibromas usually occur in the neck, pelvis, and extremities. Jaws and oral cavity plexiform neurofibromas have also been described. Magnetic resonance (MR) patterns for neurofibromas are typical. They include low-to-intermediate signal intensity on T1-weighted images, enhancement of the solid component of the tumor after contrast medium administration, heterogeneity on T2-weighted images, and in some cases, multiple target signs due to a collagen central area. We report MR findings of two neurofibromatosis type 1 (NF1) patients with enlarging tongue plexiform neurofibromas.

Purpose: To evaluate a patient population affected by Neurofibromatosis type 1 (NF1) with special reference to optic pathway gliomas., Material and Methods: A total of 419 NF1 patients (222 men, 197 women) were retrospectively evaluated to show incidence, biological behaviour, neuroradiological and clinical presentation of optic pathway gliomas. Central Nervous System MR and ophthalmologic evaluations were reviewed., Results: Thirty-two patients out of 419 (7.6%) showed the presence of optic pathway gliomas. Of these, 28 (87.2%) patients showed tumoral involvement of the optic chiasma. The right intracranial optic nerve was involved in 15 patients (46.8%), the left intracranial optic nerve in 18 (56.2%), the right extracranial optic nerve in 11 (34.3%), the left extracranial optic nerve in 10 (31.2%) and the right and left optic tracts in 6 (18.7%) patients. Geniculate body and optic radiation were not involved by tumour diffusion. Visual acuity testing was positive in 26/32 (81.2%), the fundus oculi in 11/32 (34.3%) patients and the visual field evaluation in 12/32 (37.5%) patients., Conclusions: In this study we showed an high correlation between optic pathway tumours and ophthalmologic abnormalities confirming the usefulness of an integrated clinical-neuroradiological approach in patients affected by NF1. We also described the biological behaviour of these tumours in our NF1 patient population.

In subjects with neurofibromatosis type 1 (NF1), we show that a reduction in the visual field is the most sensitive indicator of gliomas along the optic pathway. Therefore, we conclude that a visual field evaluation is the most sensitive clinical test among those evaluated to predict the presence of optic pathway pathology on an MRI examination. These data may contribute to the establishment of more precise guidelines for the evaluation and treatment of children with NF1.

A patient with neurofibromatosis type 1 was found to have an enhancing mass in the hypothalamus and in the anterior optic pathway. A 3-month MR study showed a reduction in the size and enhancement of the mass. At a 9-month MR follow-up the mass disappeared and ceased to enhance. This report shows the unusual behaviour of a hypothalamic/chiasmatic mass confirming that in such asymptomatic cases the conservative management can be considered the treatment of choice.

Purpose: To analyze the extracerebral manifestations of type 1 neurofibromatosis (NF-1), with special reference to peripheral nerve tumors., Material and Methods: The findings of 376 NF-1 patients (194 men and 182 women; age range: 0.1-48 years, mean: 8.1) were retrospectively reviewed. The patients had been submitted to abdominopelvic and superficial US and, in case of abnormal US findings or in the presence of symptoms, to CT and/or MRI. In addition, we considered 5 more patients (2 men and 3 women; age range: 50-72 years, mean: 64.4) with incomplete forms of NF-1 diagnosed after the finding of nerve sheath tumors. Biopsy (12 cases), surgery (10 cases), or clinical-instrumental follow-up were the study criteria., Results: In the first group of patients we identified 91 cutaneous, 222 subcutaneous, 11 pendulous and 25 internal neurofibromas. Plexiform neurofibromas were found in the neck (1 case), chest (6 cases), abdomen (16), pelvis (8). We also found 1 benign and 1 malignant Schwannomas, 2 nerve sheath fibrosarcomas, 1 dopamine-producing sympatoma and 1 spermacytoma. As for the second group of patients, we had 2 Schwannomas, 1 pulmonary neurofibroma, and 2 multiple plexiform neurofibromas. The neurofibromas exhibited homogeneous US hypoechogenicity or slight echogenicity, with little contrast enhancement at CT. MR showed peripheral hyperintensity and central hypointensity on T2-weighted sequences and marked contrast enhancement after gadolinium, sometimes with mostly central uptake. The plexiform neurofibromas, which are typical of NF-1, had poorly-defined or infiltrating margins, with similar findings to the previous ones but sometimes with less homogeneous patterns at both US and CT. The Schwannomas, which are a less common finding in NF-1, exhibited different features at MRI and CT, namely pseudo-liquid or solid-inhomogeneous patterns with irregular and inhomogeneous contrast enhancement relative to the Antoni A/B tumor component. In the malignant lesions we observed infiltrating patterns, with irregular and inhomogeneous contrast enhancement, arranged asymmetrically relative to the contralateral lesion., Conclusions: Extra-axial neoplasms are a frequent finding in NF-1. Despite the extremely variable appearances of some lesions (particularly Schwannomas), the typical plexiform neurofibroma exhibits characteristic patterns. The diagnosis of malignancy often requires bioptic confirmation.