Tumefactive demyelination, an uncommon form of tacrolimus neurotoxicity

Immunopathology of Tumefactive Demyelinating Lesions-From Idiopathic to Drug-Related Cases

Tumefactive demyelinating lesions (TDL) represent a diagnostic dilemma for clinicians, and in rare atypical cases a collaboration of a neuroradiologist, a neurologist, and a neuropathologist is warranted for accurate diagnosis. Recent advances in neuropathology have shown that TDL represent an umbrella under which many different diagnostic entities can be responsible. TDL can emerge not only as part of the spectrum of classic multiple sclerosis (MS) but also can represent an idiopathic monophasic disease, a relapsing disease with recurrent TDL, or could be part of the myelin oligodendrocyte glycoprotein (MOG)- and aquaporin-4 (AQP4)-associated disease. TDL can appear during the MS disease course, and increasingly cases arise showing an association with specific drug interventions. Although TDL share common features with classic MS lesions, they display some unique features, such as extensive and widespread demyelination, massive and intense parenchymal infiltration by macrophages along with lymphocytes (mainly T but also B cells), dystrophic changes in astrocytes, and the presence of Creutzfeldt cells. This article reviews the existent literature regarding the neuropathological findings of tumefactive demyelination in various disease processes to better facilitate the identification of disease signatures. Recent developments in immunopathology of central nervous system disease suggest that specific pathological immune features (type of demyelination, infiltrating cell type distribution, specific astrocyte pathology and complement deposition) can differentiate tumefactive lesions arising as part of MS, MOG-associated disease, and AQP4 antibody-positive neuromyelitis optica spectrum disorder. Lessons from immunopathology will help us not only stratify these lesions in disease entities but also to better organize treatment strategies. Improved advances in tissue biomarkers should pave the way for prompt and accurate diagnosis of TDL leading to better outcomes for patients.

Imaging spectrum of central nervous system complications of hematopoietic stem cell and solid organ transplantation

Neurologic complications are common after hematopoietic stem cell transplantation (HSCT) and solid organ transplantation (SOT) and affect 30-60% of transplant recipients. The aim of this article is to provide a practical imaging approach based on the timeline and etiology of CNS abnormalities, and neurologic complications related to transplantation of specific organs. The lesions will be classified based upon the interval from HSCT procedure: pre-engraftment period <30 days, early post-engraftment period 30-100 days, late post-engraftment period >100 days, and the interval from SOT procedure: postoperative phase 1-4 weeks, early posttransplant syndromes 1-6 months, late posttransplant syndromes >6 months. Further differentiation will be based on etiology: infections, drug toxicity, metabolic derangements, cerebrovascular complications, and posttransplantation malignancies. In addition, differentiation will be based on complications specific to the type of transplantation: allogeneic and autologous hematopoietic stem cells (HSC), heart, lung, kidney, pancreas, and liver. Thus, in this article we emphasize the strategic role of neuroradiology in the diagnosis and response to treatment by utilizing a methodical approach in the work up of patients with neurologic complications after transplantation.

Rapid Resolution of Tacrolimus Intoxication–Induced AKI With a Corticosteroid and Phenytoin

Objective: To report a novel approach to the management of tacrolimus intoxication that leads to rapid normalization of serum tacrolimus concentrations. Case Summary: A 9-year-old female renal transplant recipient developed a severe tacrolimus intoxication as a result of prolonged diarrhea, which resulted in acute kidney injury, severe dehydration, and neurological symptoms. We used a combination of intravenous steroids and intravenous phenytoin to normalize the tacrolimus level from 32 to 5 ng/mL in less than 24 hours, with complete resolution of symptoms and signs. Discussion: Tacrolimus intoxication is a rare event but may result in life-threatening complications. Treatment recommendations beyond holding the drug and enzyme induction with phenytoin or phenobarbital are elusive. This approach leads to a relatively slow normalization of the tacrolimus level over 72 hours. The authors hypothesized that additional induction of the p-glycoprotein through steroids was synergistic. Conclusions: The combination of phenytoin and a corticosteroid may be an effective approach that leads to rapid normalization of severely elevated tacrolimus levels.

Lesser-known myelin-related disorders: focal tumour-like demyelinating lesions

INTRODUCTION

Focal tumour-like demyelinating lesions are defined as solitary demyelinating lesions with a diameter greater than 2 cm. In imaging studies, these lesions may mimic a neoplasm or brain abscess; as a result, invasive diagnostic and therapeutic measures may be performed that will in some cases increase morbidity. Our aim was to analyse and characterise these lesions according to their clinical, radiological, and pathological characteristics, and this data in addition to our literature review will contribute to a better understanding of these lesions.

METHODS

This descriptive study includes 5 cases with pathological diagnoses. We provide subject characteristics gathered through reviewing their clinical, radiology, and pathology reports.

RESULTS

Patients' ages ranged from 12 to 60 years; 3 patients were female. The time delay between symptom onset and hospital admission was 3 to 120 days. Clinical manifestations were diverse and dependent on the location of the lesion, pyramidal signs were found in 80% of patients, there were no clinical or radiological signs of spinal cord involvement, and follow-up times ranged from 1 to 15 years.

CONCLUSION

Brain biopsy is the gold standard for the diagnosis of demyelinating tumour-like lesions; however, their clinical features, along with several magnetic resonance imaging features such as open ring enhancement, venular enhancement, the presence of glutamate in spectroscopy, and others, may be sufficient to differentiate neoplastic lesions from focal tumour-like demyelinating lesions.

Tumefactive demyelination: an approach to diagnosis and management

Tumefactive lesions are an uncommon manifestation of demyelinating disease and can pose a diagnostic challenge in patients without a pre-existing diagnosis of multiple sclerosis. Choosing when to biopsy a tumefactive lesion to exclude alternative pathology can be difficult. Other questions include how best to treat an acute attack as well as the optimal timing of therapy to prevent relapse. This article aims to review the available literature for tumefactive demyelination and to propose an approach to diagnosis and management. We argue that disease modifying therapy should be considered for acute tumefactive demyelinating lesions only once criteria of dissemination in time and space are fulfilled and the diagnosis of multiple sclerosis is confirmed.

Neurological complications of transplantation: part I: hematopoietic cell transplantation

Hematopoietic cell transplantation (HCT) is the preferred treatment for an expanding range of neoplastic and nonmalignant conditions. Increasing numbers of solid organ transplantations (SOTs) add an additional population of immunosuppressed patients with multiple potential neurological problems. While the spectrum of neurological complications varies with conditioning procedure and hematopoietic cell or solid organ source, major neurological complications occur with all transplantation procedures. This 2 part review emphasizes a practical consultative approach to central and peripheral nervous system problems related to HCT or SOT with clinical and neuroimaging examples from the authors' institutional experience with the following conditions: the diversity of manifestations of common infections such as varicella zoster virus, Aspergillus, and progressive multifocal leukoencephalopathy (PML), drug therapy-related complications, stroke mechanisms, the spectrum of graft versus host disease (GVHD), and neurologically important syndromes of immune reconstitution inflammatory syndrome (IRIS), posterior reversible encephalopathy syndrome (PRES), and posttransplantation lymphoproliferative disorder (PTLD). These complications preferentially occur at specific intervals after HCT and SOT, and neurological consultants must recognize an extensive spectrum of syndromes in order to effect timely diagnosis and expedite appropriate treatment.

CNS infections in patients with cancer

PURPOSE OF REVIEW

This article provides a practical clinical approach to potential CNS infections in patients with cancer, discusses problematic presentations of posterior reversible encephalopathy syndrome and immune reconstitution inflammatory syndrome, and includes specific testing and treatment recommendations for bacterial meningitis, invasive fungal infections, and opportunistic viral infections.

RECENT FINDINGS

The major deficits predisposing patients with cancer to CNS infection are neutropenia, barrier disruption, B-lymphocyte or immunoglobulin deficiency, and impaired T lymphocyte-mediated immunity. Evolving patterns of drug resistance and prophylactic antimicrobial regimens have altered the timing and range of organisms causing infections. Increasingly intensive immunosuppression has made new groups of patients vulnerable to infections such as progressive multifocal leukoencephalopathy. New MRI sequences offer the potential to diagnose such infections earlier, at a stage when they are more treatable.

SUMMARY

Despite improved prophylactic and therapeutic antibiotic regimens, CNS infections remain an important source of morbidity and mortality among several cancer patient groups, particularly those patients undergoing craniotomy and those with hematologic malignancies receiving either hematopoietic cell transplantation or other intensive chemotherapy regimens.

Conventional and advanced magnetic resonance imaging in tumefactive demyelination

BACKGROUND

Tumefactive demyelination (TD) is a relatively uncommon entity which mimics other focal intracranial lesions. Conventional radiological findings in tumefactive demyelination have been well described. However, DTI and MRS findings in TD have not been studied in detail.

PURPOSE

To evaluate the usefulness of conventional magnetic resonance imaging (MRI), multivoxel 1H spectroscopy (MRS) and diffusion tensor imaging (DTI) in diagnosis and follow-up of TD of the brain.

MATERIAL AND METHODS

Clinical and imaging findings of 18 patients were reviewed. MR imaging data which included conventional imaging as well as MRS and DTI were reviewed. At TE 135ms MRS various metabolite ratios were calculated at different depths of the demyelinating lesions. At TE 30 ms, glutamate-glutamine (GLX-2.1-2.5 ppm) was compared in the lesion to the contralateral normal side. DTI data were available for 15 patients and Dav (mean diffusivity) and trace values were recorded from central and peripheral layers of the index lesion. Histopathological (9 patients) and therapeutic response (9 patients) on follow-up imaging were taken as the diagnostic criterion. In addition, the follow-up MRI scans available were also reviewed.

RESULTS

Characteristic peripheral 'broken ring' type of contrast enhancement was noted in 12 cases. Two or three concentric distinct zones were noted on imaging with distinct metabolic and structural signature in most cases. On TE 135ms, the central part showed variable Choline (Cho) and significantly low N-Acetyl Aspartate (NAA). DTI demonstrated high Dav and very low trace value in this zone. The intermediate area showed higher Cho and lower NAA compared to contralateral normal side. The outermost layer, which corresponded to the contrast enhancing areas on MRI, showed high Cho, lower NAA, and restricted diffusion on DTI. The GLX increase was noted in tumefactive lesions. Lactate was observed in all patients and it appeared higher at the center compared to the periphery of lesions. Follow-up imaging showed shrinkage of index lesions, disappearance of contrast enhancement, and diffusion restriction. MRS showed, persistent abnormalities on follow-up imaging.

CONCLUSION

Tumefactive demyelinating lesions reveal different microstructural changes at different depths of the lesion and this unique feature may be useful in differentiating them from other focal lesions of brain.