SOMATIC DEFICIENT MISMATCH REPAIR ASSESSED BY IMMUNOHISTOCHEMISTRY AND CLINICAL FEATURES IN BRAZILIAN GLIOBLASTOMA PATIENTS.

BACKGROUND: Glioblastoma (GBM) is the most frequent primary malignant CNS tumor. Deficient mismatch repair (dMMR) is associated with better prognosis and is a biomarker for immunotherapy. Evaluation of MMR by immunohistochemistry (IHC) is accessible, cost effective, sensitive, and specific. AIM: Our objective was to investigate MMR proteins in adult GBM patients. MATERIALS AND METHODS: We retrospectively analyzed 68 GBM samples to evaluate the proficiency of MMR genes expression assessed by IHC. Clinicopathologic and molecular features were compared in proficient (pMMR) or dMMR. RESULTS: 10 (14.7%) samples showed dMMR, and the most frequent was MSH6 (100%) followed by MSH2, PMS2, and MLH1. We observed heterogeneous expression of dMMR in 5 GBMs. The median overall survival did not differ between pMMR (19.8 months; 0.2-30) and dMMR (16.9 months; 6.4-27.5) (p = 0.31). We observed a significantly higher overall survival associated with gross total resection compared to subtotal resection or biopsy (30.7 vs. 13.6 months, p = 0.02) and MGMT methylated status (29.6 vs. 19.8 months, p = 0.049). At the analysis time, 10 patients were still alive, all in the pMMR group. CONCLUSIONS: Our data demonstrated dMMR phenotype assessed by IHC in an expressive portion of GBM patients, however without significant impact on overall survival.

Neuroradiologic Phenotyping of Galactosemia: From the Neonatal Form to the Chronic Stage.

Galactosemia is a rare genetic condition caused by mutation of enzymes involved in galactose and glucose metabolism. The varying clinical spectrum reflects the genetic complexity of this entity manifesting as acute neonatal toxicity syndrome, requiring prompt diagnosis and treatment, to more insidious clinical scenarios as observed in the subacute and chronic presentations. The current literature predominantly focuses on the long-standing sequelae of this disease. The purpose of this multicenter clinical report comprising 17 patients with galactosemia is to highlight the MR imaging patterns encompassing the whole spectrum of galactosemia, emphasizing the 3 main clinical subtypes: 1) acute neonatal presentation, with predominant white matter edema; 2) subacute clinical onset with a new finding called the "double cap sign"; and 3) a chronic phase of the disease with heterogeneous imaging findings. The knowledge of these different patterns together with MR spectroscopy and the clinical presentation may help in prioritizing galactosemia over other neonatal metabolic diseases and prevent possible complications.

Gadolinium-Enhanced Susceptibility-Weighted Imaging in Multiple Sclerosis: Optimizing the Recognition of Active Plaques for Different MR Imaging Sequences.

BACKGROUND AND PURPOSE: Gadolinium SWI is MR imaging that has recently been reported to be effective in the evaluation of several neurologic disorders, including demyelinating diseases. Our aim was to analyze the accuracy of gadolinium SWI for detecting the imaging evidence of active inflammation on MS plaques when a BBB dysfunction is demonstrated by a focal gadolinium-enhanced lesion and to compare this technique with gadolinium-enhanced T1 spin-echo and T1 spin-echo with magnetization transfer contrast. MATERIALS AND METHODS: MR imaging studies of 103 patients (170 examinations) were performed using a 1.5T scanner. Two neuroradiologists scrutinized signal abnormalities of the demyelinating plaques on gadolinium SWI and compared them with gadolinium T1 before and after an additional magnetization transfer pulse. Interrater agreement was evaluated among gadolinium T1 magnetization transfer contrast, gadolinium SWI, and gadolinium T1 spin-echo using the κ coefficient. The T1 magnetization transfer contrast sequence was adopted as the criterion standard in this cohort. Thus, the sensitivity, specificity, positive predictive value, and negative predictive value were calculated for gadolinium T1 spin-echo and gadolinium SWI sequences. RESULTS: Differences in BBB dysfunction were evident among gadolinium SWI, gadolinium T1 spin-echo, and gadolinium T1 magnetization transfer contrast. Gadolinium T1 magnetization transfer contrast demonstrated the highest number of active demyelinating plaques. Gadolinium SWI was highly correlated with gadolinium T1 magnetization transfer contrast in depicting acute demyelinating plaques (κ coefficient = 0.860; sensitivity = 0.837), and these techniques provided better performance compared with gadolinium T1 spin-echo (κ coefficient = 0.78; sensitivity = 0.645). CONCLUSIONS: Gadolinium SWI was able to better detect BBB dysfunction in MS plaques and had a better performance than gadolinium T1 spin-echo. Increasing SWI sequence applications in clinical practice can improve our knowledge of MS, likely allowing the addition of BBB dysfunction analysis to the striking findings of the previously reported central vein sign.

Combined pituitary hormone deficiency and PROP-1 mutation in two siblings: a distinct MR imaging pattern of pituitary enlargement.

Mutations of the PROP-1 gene are the most frequent genetic defect in patients with combined pituitary hormone insufficiency. We present the cases of 2 siblings with PROP-1 mutations whom we observed longitudinally. Their initial pituitary MR imaging examinations showed identical findings: an enlarged adenohypophysis, with striking hypointensity on T2-weighted images and slight hyperintensity on T1-weighted images. In one of the children, the follow-up MR imaging obtained 3 years after hormonal replacement revealed a decrease in the size of the anterior pituitary lobe.

Multinodular and Vacuolating Neuronal Tumor of the Cerebrum: A New "Leave Me Alone" Lesion with a Characteristic Imaging Pattern.

Multinodular and vacuolating neuronal tumor of the cerebrum is a recently reported benign, mixed glial neuronal lesion that is included in the 2016 updated World Health Organization classification of brain neoplasms as a unique cytoarchitectural pattern of gangliocytoma. We report 33 cases of presumed multinodular and vacuolating neuronal tumor of the cerebrum that exhibit a remarkably similar pattern of imaging findings consisting of a subcortical cluster of nodular lesions located on the inner surface of an otherwise normal-appearing cortex, principally within the deep cortical ribbon and superficial subcortical white matter, which is hyperintense on FLAIR. Only 4 of our cases are biopsy-proven because most were asymptomatic and incidentally discovered. The remaining were followed for a minimum of 24 months (mean, 3 years) without interval change. We demonstrate that these are benign, nonaggressive lesions that do not require biopsy in asymptomatic patients and behave more like a malformative process than a true neoplasm.

Recognizing Autoimmune-Mediated Encephalitis in the Differential Diagnosis of Limbic Disorders.

Limbic encephalitis is far more common than previously thought. It is not always associated with cancer, and it is potentially treatable. Autoantibodies against various neuronal cell antigens may arise independently or in association with cancer and cause autoimmune damage to the limbic system. Neuroimaging plays a key role in the management of patients with suspected limbic encephalitis by supporting diagnosis and excluding differential possibilities. This article describes the main types of autoimmune limbic encephalitis and its mimic disorders, and emphasizes their major imaging features.