Central nervous system lymphoma in children

This paper describes the rare MR and CT features of central nervous system (CNS) lymphoma in immunocompetent children and in survivors of childhood acute lymphoblastic leukemia (ALL) and discusses the causative role of cranial irradiation and/or leukoencephalopathy preceding central nervous system (CNS) lymphoma in survivors of childhood leukemia. The authors reviewed MR and CT scans of 3 children with biopsy-proved CNS lymphoma. One child had tumor infiltration within the optic nerve sheaths and optic chiasm by previously known non-Hodgkin lymphoma. In 2 patients, CNS lymphoma developed 8 and 10 years after initial ALL treatment. In both cases CNS lymphoma was preceded by cranial irradiation and leukoencephalopathy. A single lesion was present in 3 out of 4 patients. All lesions were isointense or hypointense on the T1-weighted images relative to gray matter and showed homogeneous enhancement. One lesion was centered in the central gray matter, one lesion was centered within a cerebral hemisphere, one lesion was in optic nerve, and there were 2 parasellar lesions. CNS lymphoma has a variable appearance in children. Knowledge of risk factors in children may help in the early recognition of disease, allowing for timely intervention. This may prompt early biopsy or a conservative management in the appropriate clinical setting.     

Assessment of paramedian thalamic infarcts: MR imaging,clinical features and prognosis

Considering the highly variable vascular supply of the thalamic nuclei, MRI and clinical syndromes can be heterogeneous in ischemic diseases. We attempt to determine MRI pattern and to analyse neurological features and prognosis of paramedian infarcts. In a prospective case series within 5 years from 1999 to 2003, MRI, MRA and clinical symptoms of 38 consecutive patients were analysed. The inferomedial (posterior thalamoperforating artery) territory was affected in 89%, and lesions in the anterolateral (tuberothalamic artery) territory occurred in 42%. However, definite attribution to anterolateral or inferomedial territories was not possible in 13%. Neurological manifestations were somnolence (87%), hemisyndromes (79%), cognitive deficits (58%), oculomotor nerve palsies (53%) and vertical gaze palsies (39%). The most common aetiologies were cardiac embolism (42%), intraarterial embolism (16%), small vessel disease (13%) and large artery arteriosclerosis (13%). Pathological MRA findings were encountered in 55%, and in 18%, lesions were only visible on diffusion-weighted imaging. Correlation of MRI pattern and neurological symptoms points out anterolateral thalamic lesions as the cause of amnestic deficits. Intracranial MRA allows a non-invasive prediction of basilar tip occlusion. Our results underline the necessity of additional diffusion-weighted imaging in detecting small thalamic and midbrain lesions.     

Granulocytic sarcoma in children

We report three children with leukaemia (two acute myeloid and one acute lymphoblastic) and granulocytic sarcoma in the skull, orbit and sinuses. Lesions in these sites in children, with or without bone changes, are suggestive of systemic diseases such as lymphoproliferative conditions. Although involvement by granulocytic sarcoma, with or without acute myeloid leukaemia, is described, an association with acute lymphoblastic leukaemia is rare. Recognition of this rare entity is important, because early aggressive chemotherapy can bring about regression of the tumour and improve survival.     

Typing of pneumococcal surface protein A (PspA) in Streptococcus pneumoniae isolated during epidemiological surveillance in Brazil: towards novel pneumococcal protein vaccines

Pneumococcal protein vaccine based on pneumococcal surface protein A (PspA) is in development with the potential to offer broad range of protection against different strains. We have investigated the frequency of PspA family 1 (Fam1) and family 2 (Fam2) proteins among Streptococcus pneumoniae recovered from ongoing surveillance in Brazil. Fam1 and Fam2 were expressed in comparable rates among 366 isolates, with the potential coverage of 94.3%. PspA families were not associated to age group or source of isolates. However, considering the significant tendency of increasing prevalence of Fam2 associated to widespread dissemination of the genetically-related resistant strains, the monitoring of the PspA families derived from population-based data may be necessary in the context of vaccine development.     

Characterization of haemophilus influenzae isolated from invasive disease in Brazil from 1990 to 1999

The Haemophilus influenzae serotype b (Hib) conjugate vaccine was introduced in the National Immunization Program in Brazil in the second half of 1999. A retrospective analysis on serotypes, biotypes, and antimicrobial resistance of Hi invasive strains obtained through Hi survey was conducted to document the characteristics of this pathogenic agent during a decade prior the use of Hib vaccine. A total 3,204 strains from 1990 to 1999 were studied, being 88.2% isolated from cerebrospinal fluid, 10.7% from blood, and 1.1% from pleural fluid. The rate of 90.9% of strains was obtained from children up to 4 years old, and the age group >6 months old to 1 year was the higher risk to Hi infection. Type b was, by far, the most common type (97.8%), followed in frequency by type a (0.5%); only 1.5% was a nontypable strain. Biotypes I and II accounted for 97.8% of isolates. Resistance to ampicillin (AM) and chloramphenicol (CO) was detected at rates of 18.1% and 19.1%, respectively, whereas simultaneous resistance to AM and CO was identified in 13.9% of strains. Total concordance was found between AM resistance and beta-lactamase production. No strain showed resistance to ceftriaxone and rifampicin. In conclusion, the data generated through this laboratory-based surveillance should serve as a reference for assessing the impact of Hib vaccination and to detect changes on the pattern of Hi diseases in the country.     

Wernicke encephalopathy: MR findings and clinical presentation

Wernicke encephalopathy (WE) is a severe neurological disorder caused by vitamin B1 deficiency. The aim of the study was to analyse MRI findings typical for this disease and to evaluate the significance of their correlations with clinical symptoms. Magnetic resonance images and clinical features of 12 patients with WE were analysed. The patients underwent MR imaging within 3–14 days after onset of clinical symptoms. In 7 of 12 patients MR imaging showed symmetrical diencephalic and midbrain lesions. Postcontrast T1-weighted images from 5 of 9 patients examined during the initial 6 days of acute WE showed a subtle enhancement of the mamillary bodies, the tectal plate, the periaqueductal area and the periventricular region of the third ventricle including the paramedian thalamic nuclei. In addition, T2-weighted and fluid-attenuated inversion recovery (FLAIR) images revealed hyperintense signals in these regions (except for 2 patients where the mamillary bodies were normal). Hyperintense lesions on T2-weighted images without any enhancement on postcontrast T1-weighted images were detected in 2 patients by MR imaging performed 11 or 14 days after onset of WE. Patients with hyperintensities on T2-weighted images of the periventricular region of the third ventricle and the paramedian thalamic nuclei had poor recovery from their mental dysfunction. The MR examination in case of WE shows a typical pattern of lesions in 58% of cases. Enhancement of the mamillary bodies, the periventricular region of the third ventricle including the paramedian thalamic nuclei, and the periaqueductal area on postcontrast T1-weighted images can be observed in the initial period after clinical onset of symptoms and are characteristic signs of the acute stage of WE. Hyperintense lesions in the periventricular region and the paramedian thalamic nuclei on T2-weighted and FLAIR images in the subacute stage of WE and enhancement on postcontrast T1-weighted images of the mamillary bodies and the paramedian thalamic nuclei are indicators of poor prognosis despite vitamin B1 substitution. Electronic Publication     

Correlation of Tc-99m-red blood cell phleboscintigraphy with clinical severity of chronic venous disease

Equilibrium red blood cell phleboscintigraphy of the lower limbs for the diagnostic management of chronic venous disease has been proposed. The aim of this study was to verify the correlation of the phleboscintigraphic assessment of chronic venous disease with the clinical grading of the severity of the disease, since other diagnostic modalities have been recently demonstrated a poor and only partial correlation. Equilibrium Tc-99m-red blood cell phleboscintigraphy was performed in 27 patients with chronic venous disease. Scintigraphic images of 52 limbs were classified according to a four-class qualitative grading of the severity of the venous disease, and a quantitative scintigraphic index (saphena /femoral ratio) was assigned to each limb. The scintigraphic qualitative grading showed a highly significant correlation with the clinical grading (Rs=0.82, p<0.01), a good interobserver and intraobserver agreement (86.5% and 92.3%, respectively) and more than 90% sensitivity and specificity to identify the categories "minimal or no chronic venous disease" or "more significant disease" (assessed according to the Bayes theorem). Sensitivity and specificity results for the quantitative assessment were not as good. Phleboscintigraphy correlates well with the clinical grading of the severity of chronic venous disease of the lower limbs and may have potential as a valuable diagnostic tool for the noninvasive assessment of chronic venous disease.