Although chemotherapy treatment is associated with an increased risk of thrombosis, the pathogenic mechanisms for the thrombogenic effect of chemotherapeutic drugs are poorly understood. We hypothesize that exposure of vascular endothelial cells to chemotherapeutic agents results in the loss of a thromboresistant phenotype. In this study, we examined the effects of the chemotherapeutic agent doxorubicin on the endothelium-based protein C anticoagulant pathway. The endothelial cell protein C receptor (EPCR) and thrombomodulin are two endothelial cell surface receptors required for the conversion of zymogen protein C to the anticoagulant enzyme activated protein C. Exposure of human umbilical vein endothelial cells (HUVEC) to doxorubicin resulted in a dose-and time-dependent decrease in cell surface EPCR levels. This decrease occurred as a result of receptor shedding as well as from a down-regulation in EPCR mRNA levels. In contrast, doxorubicin treatment of HUVECs resulted in a dose-and time-dependent increase in cell surface thrombomodulin attributed to an up-regulation of thrombomodulin mRNA levels. The net effect of the doxorubicininduced changes in EPCR and thrombomodulin levels was a decrease in the capacity of HUVECs to convert protein C to activated protein C. Preliminary studies suggest that doxorubicin free radical metabolites mediate the doxorubicin-induced changes in EPCR expression but not those of thrombomodulin expression. In summary, these results suggest that doxorubicin alters the hemostatic balance of endothelial cells by down-regulating the endotheliumbased protein C anticoagulant pathway.
C olloid cysts are benign intracranial lesions usually located in the anterosuperior part of the third ventricle.7 Rarely, they arise from the lateral ventricles, fourth ventricle, 1,4 or outside the ventricular system. 7 Between 40% and 50% are asymptomatic and account for approximately 0.5%-1% of intracranial tumors. A large colloid cyst is usually defined as > 3 cm and is extremely rare.2 Few cases have been reported of so-called huge colloid cysts that are > 5 cm. We present a case of a giant 8-cm third ventricle colloid cyst; larger than any other reported in the literature, it was a diagnostic challenge due to its atypical clinical presentation and unique imaging appearance. Case ReportHistory and Examination. A 42-year-old woman presented to the emergency department with acute onset of complete vision loss in her left eye that later resolved. She also reported a 6-month history of progressive memory loss, left hemiparesis, and an unsteady gait. On physical examination she had an ataxic, unsteady gait, and funduscopic examination showed bilateral papilledema.Neuroimaging. Contrast-enhanced head CT scans demonstrated a large cystic mass, probably within the ventricular system. It measured approximately 8 cm in maximum diameter, lacked calcification, contained a small area of enhancement, and was causing obstructive hydrocephalus (Fig. 1A and B). A contrast-enhanced MRI study of the brain showed a largely cystic lesion arising from the third ventricle that was predominantly T2 hypointense (Fig. 1C) and T1 hyperintense, with an enhancing nodule ( Fig. 1D and E). It demonstrated a focus of restriction on diffusion-weighted imaging and foci of blooming, suspicious for hemorrhage on susceptibilityweighted imaging (Fig. 1F and G). The differential diagnosis at that time included craniopharyngioma, ependymoma, neuroenteric cyst, teratoma, cystic intraventricular cavernous malformation, and a large colloid cyst. Operation.A left frontal craniotomy with resection of the cystic lesion was performed. Intraoperatively the cyst wall was very tough, and a thick "anchovy paste"-type substance was drained. Under intraoperative mi- The finding of a colloid cyst on neuroimaging is often incidental. These lesions are usually located at the foramen of Monro, are hyperdense on CT scans, and generally demonstrate signal intensity of water on MR images, although this depends on their content. When symptomatic, they frequently present with headaches and nausea due to an obstructive hydrocephalus. The authors describe a case of a giant colloid cyst in a patient presenting with complete left-sided vision loss and progressive memory loss, two very atypical findings in colloid cyst presentation. Imaging findings were also atypical, and this case proved to be a diagnostic dilemma because of its clinical and radiological presentation. Histopathological investigation was of utmost importance in the final diagnosis of a colloid cyst. To the authors' knowledge this colloid cyst is larger than any other described in the literature.
SummaryBackgroundA cerebral spinal fluid (CSF) cavity within the conus medullaris has been described by the term ventriculus terminalis (VT) or the fifth ventricle. The finding of a VT on MRI imaging of the lumbar spine is often incidental but may be found in patients with low back pain or neuromuscular deficits. These lesions, when identified, are thought to regress or remain stable in terms of size, although some have been described to enlarge in the presence of post-traumatic meningeal hemorrhages or deformities of the vertebral canal.Case ReportWe describe a case of a slowly growing VT in a patient with progressing lower limb weakness without any history or imaging findings of trauma or spinal canal abnormalities.ConclusionsWe present an intriguing case of a slowly growing VT in a woman with progressive neurological symptoms. Surgical fenestration provided complete symptomatic relief and follow-up imaging two years after surgery demonstrated no evidence of recurrence. This, to our knowledge, is the first described case of a slowly enlarging VT independent of any other imaging findings.
Pre-procedural blood screening did not predict bleeding in hospitalized children without a known bleeding diathesis undergoing PICC insertion. The rarity of major bleeding complications and need for conversion to a central venous line did not support a need for laboratory screening.
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