ABSTRACT
Background and Aims: Malignant peripheral nerve sheath tumors (MPNSTs) are the leading cause of mortality in patients with neurofibromatosis type-1 (NF1)); however, they may also arise sporadically. Differences in magnetic resonance imaging (MRI) features between MPNSTs arising in NF1 subjects versus non-NF1 subjects have not been studied before. The accuracy of MRI in distinguishing MPNSTs from benign peripheral nerve sheath tumors (BPNSTs) has also been debated. The objective of this study was to determine the potential differentiating MRI features between (a) NF1-related and non-NF1-related MPNSTs and (b) MPNSTs and BPNSTs. Materials and Methods: We retrospectively evaluated the MRI studies of 21 patients (12 NF1 subjects and nine non-NF1 subjects) with MPNSTs and 35 patients with BPNSTs. In all studies, the lesions were assessed in terms of size, margins, T1 and T2 signal characteristics, internal architecture, pattern of contrast enhancement, invasion of adjacent structures and necrosis/cystic degeneration as well as for the presence of tail-, target- and split-fat signs. Results: MPNSTs of NF1 subjects occurred at an earlier age and displayed a higher incidence of necrosis/cystic degeneration compared with MPNSTs of non-NF1 subjects. Compared with BPNSTs, MPNSTs were significantly larger at the time of diagnosis and demonstrated a higher incidence of ill-defined margins (specificity 91%, sensitivity 52%) and invasion of adjacent structures (specificity 100%, sensitivity 43%). Conclusions: Differences exist between NF1-related and non-NF1-related MPNSTs regarding the age of occurrence and MRI appearance. In the MRI evaluation of peripheral nerve sheath tumors, the presence of ill-defined tumor margins and/or invasion of adjacent structures are highly specific for malignancy.
ABSTRACT
Can suicide be predicted? If we know that more than 50 per cent of suicide persons have visit a doctor before and we know probable clinic markers of suicide intent, we should look for biochemical suicide markers that have use in the medical praxis. Suicide behavior is associated mainly to alterations of the serotoninergic system. The most consistent indicator of suicide risk in the history in course is the metabolism of the serotonine, 5HIAA, mainly in the CSF, also can be use like helpers in the increase of the urinal 17 hidrocortizone, the increase of plasmatic cortisol higher than 20mcg per cent, positivity of the dexametazone suppression test, the answer of TSH to TRH, the latency of REM increase in the electroencephalogram of sleep and seric cholesterol decrease. Perhaps all this investigations in the biochemical of suicide have a little application in medicine. That's why we make a revision in the principal and probable suicide biologic markers and we intent to help in the search of one that have application in the medical praxis, like cholesterol. We are doing a investigation work between cholesterol association, suicide behavior and depression, based in the serotoninergic hypothesis of suicide etiopathogeny.