Gadolinium enhancement patterns of tumefactive demyelinating lesions: correlations with brain biopsy findings and pathophysiology

Isolated large demyelinated plaque with clinical and radiologic appearance suggestive of cervical intramedullary tumor diagnosed after surgery

Isolated spinal demyelinating lesions are rare and often associated with multiple sclerosis. While initial radiological findings may suggest a tumor, a definitive diagnosis requires a histological diagnosis. A 45-year-old woman presented with progressive spastic tetraparesis for 1 week. She had no prior history of neurological or systemic illness. Brain and thoracic magnetic resonance imaging (MRI) were normal, but cervical MRI revealed an intramedullary tumor extending from C3 to C4. Surgery was performed. Histopathological examination revealed an inflammatory demyelinating plaque, not a tumor. The patient experienced significant improvement in her clinical condition postsurgery and remains under neurological follow-up. We discuss this case alongside a review of similar cases reported in the literature, focusing on clinical presentation, laboratory findings, MRI features, and follow-up of patients with tumor-like inflammatory demyelinating diseases of the spinal cord initially diagnosed as intramedullary tumors.

Emergent Management of Central Nervous System Demyelinating Disorders

OBJECTIVE

This article reviews the various conditions that can present with acute and severe central nervous system demyelination, the broad differential diagnosis of these conditions, the most appropriate diagnostic workup, and the acute treatment regimens to be administered to help achieve the best possible patient outcomes.

LATEST DEVELOPMENTS

The discovery of anti-aquaporin 4 (AQP4) antibodies and anti-myelin oligodendrocyte glycoprotein (MOG) antibodies in the past two decades has revolutionized our understanding of acute demyelinating disorders, their evaluation, and their management.

ESSENTIAL POINTS

Demyelinating disorders comprise a large category of neurologic disorders seen by practicing neurologists. In the majority of cases, patients with these conditions do not require care in an intensive care unit. However, certain disorders may cause severe demyelination that necessitates intensive care unit admission because of numerous simultaneous multifocal lesions, tumefactive lesions, or lesions in certain brain locations that lead to acute severe neurologic dysfunction. Intensive care may be necessary for the management and prevention of complications for patients who have severely altered mental status, rapidly progressive neurologic worsening, elevated intracranial pressure, severe cerebral edema, status epilepticus, or respiratory failure.

Tumefactive demyelinating lesions versus CNS neoplasms, a comparative study

BACKGROUND

Differentiating tumefactive demyelinating lesions (TDL) from neoplasms of the central nervous system continues to be a diagnostic dilemma in many cases.

OBJECTIVE

Our study aimed to examine and contrast the clinical and radiological characteristics of TDL, high-grade gliomas (HGG) and primary CNS lymphoma (CNSL).

METHOD

This was a retrospective review of 66 patients (23 TDL, 31 HGG and 12 CNSL). Clinical and laboratory data were obtained. MRI brain at presentation were analyzed by two independent, blinded neuroradiologists.

RESULTS

Patients with TDLs were younger and predominantly female. Sensorimotor deficits and ataxia were more common amongst TDL whereas headaches and altered mental status were associated with HGG and CNSL. Compared to HGG and CNSL, MRI characteristics supporting TDL included relatively smaller size, lack of or mild mass effect, incomplete peripheral rim enhancement, absence of central enhancement or restricted diffusion, lack of cortical involvement, and presence of remote white matter lesions on the index scan. Paradoxically, some TDLs may present atypically or radiologically mimic CNS lymphomas.

CONCLUSION

Careful evaluation of clinical and radiological features helps in differentiating TDLs at first presentation from CNS neoplasms.

Differential Diagnosis of Tumor-like Brain Lesions

Purpose of Review

Tumor-like brain lesions are rare and commonly suggest a neoplastic etiology. Failure to rapidly identify non-neoplastic causes can lead to increased morbidity and mortality. In this review, we describe 10 patients who presented with atypical, non-neoplastic tumor-like brain lesions in which brain biopsy was essential for a correct diagnosis and treatment.

Recent Findings

There has been increasing recognition of autoimmune conditions affecting the nervous system, and many of those diseases can cause tumor-like brain lesions. Currently available reports of non-neoplastic tumor-like brain lesions are scarce. Most case series focus on tumefactive demyelinating lesions, and a comprehensive review including other neuroimmunological conditions such as CNS vasculitis, neurosarcoidosis, histiocytic and infectious etiologies is lacking.

Summary

We review the literature on tumor-like brain lesions intending to increase the awareness and differential diagnosis of non-neoplastic brain tumor mimics. We advocate for earlier brain biopsies, which, in our case series, significantly changed diagnosis, management, and outcomes.

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.

Tumefactive demyelination: updated perspectives on diagnosis and management

INTRODUCTION

Tumefactive demyelination (TD) can be a challenging scenario for clinicians due to difficulties distinguishing it from other conditions, such as neoplasm or infection; or with managing the consequences of acute lesions, and then deciding upon the most appropriate longer term treatment strategy.

AREAS COVERED

The authors review the literature regarding TD covering its clinic-radiological features, association with multiple sclerosis (MS), and its differential diagnosis with other neuroinflammatory and non-inflammatory mimicking disorders with an emphasis on atypical forms of demyelination including acute disseminated encephalomyelitis (ADEM), MOG antibody-associated demyelination (MOGAD) and neuromyelitis spectrum disorders (NMOSD). We also review the latest in the acute and long-term treatment of TD.

EXPERT OPINION

It is important that the underlying cause of TD be determined whenever possible to guide the management approach which differs between different demyelinating and other inflammatory conditions. Improved neuroimaging and advances in serum and CSF biomarkers should one day allow early and accurate diagnosis of TD leading to better outcomes for patients.

A Review of Clinical and Imaging Findings in Tumefactive Demyelination

OBJECTIVE. Tumefactive demyelination mimics primary brain neoplasms on imaging, often necessitating brain biopsy. This article reviews the literature for the clinical and radiologic findings of tumefactive demyelination in various disease processes to facilitate identification of tumefactive demyelination on imaging. CONCLUSION. Both clinical and radiologic findings must be integrated to distinguish tumefactive demyelinating lesions from similarly appearing lesions on imaging. Further research on the immunopathogenesis of tumefactive demyelination and associated conditions will elucidate their interrelationship.

Differential imaging of atypical demyelinating lesions of the central nervous system

The detection of atypical and sometimes aggressive or tumefactive demyelinating lesions of the central nervous system often poses difficulties in the differential diagnosis. The clinical presentation is generally aspecific, related to the location and similar to a number of different lesions, including neoplasms and other intracranial lesions with mass effect. CSF analysis may also be inconclusive, especially for lesions presenting as a single mass at onset. As a consequence, a brain biopsy is frequently performed for characterization. Advanced MRI imaging plays an important role in directing the diagnosis, reducing the rate of unnecessary biopsies and allowing a prompt start of therapy that is often crucial, especially in the case of infratentorial lesions. In this review, the main pattern of presentation of atypical inflammatory demyelinating diseases is discussed, with particular attention on the differential diagnosis and how to adequately define the correct etiology.

Evaluation of Diagnostic Accuracy Following the Coadministration of Delta-Aminolevulinic Acid and Second Window Indocyanine Green in Rodent and Human Glioblastomas

PURPOSE

Fluorescence-guided-surgery offers intraoperative visualization of neoplastic tissue. Delta-aminolevulinic acid (5-ALA), which targets enzymatic abnormality in neoplastic cells, is the only approved agent for fluorescence-guided neurosurgery. More recently, we described Second Window Indocyanine Green (SWIG) which targets neoplastic tissue through enhanced vascular permeability. We hypothesized that SWIG would demonstrate similar clinical utility in identification of high-grade gliomas compared with 5-ALA.

PROCEDURES

Female C57/BL6 and nude/athymic mice underwent intracranial implantation of 300,000 GL261 and U87 cells, respectively. Tumor-bearing mice were euthanized after administration of 5-ALA (200 mg/kg intraperitoneal) and SWIG (5 mg/kg intravenous). Brain sections were imaged for protoporphyrin-IX and ICG fluorescence. Fluorescence and H&E images were registered using semi-automatic scripts for analysis. Human subjects with HGG were administered SWIG (2.5 mg/kg intravenous) and 5-ALA (20 mg/kg oral). Intraoperatively, tumors were imaged for ICG and protoporphyrin-IX fluorescence.

RESULTS

In non-necrotic tumors, 5-ALA and SWIG demonstrated 90.2 % and 89.2 % tumor accuracy (p value = 0.52) in U87 tumors and 88.1 % and 87.7 % accuracy (p value = 0.83) in GL261 tumors. The most distinct difference between 5-ALA and SWIG distribution was seen in areas of tumor-associated necrosis, which often showed weak/no protoporphyrin-IX fluorescence, but strong SWIG fluorescence. In twenty biopsy specimens from four subjects with HGG, SWIG demonstrated 100 % accuracy, while 5-ALA demonstrated 75-85 % accuracy; there was 90 % concordance between SWIG and 5-ALA fluorescence.

CONCLUSION

Our results provide the first direct comparison of the diagnostic utility of SWIG vs 5-ALA in both rodent and human HGG. Given the broader clinical utility of SWIG compared with 5-ALA, our data supports the use of SWIG in tumor surgery to improve the extent of safe resections.

CLINICAL TRIAL

NCT02710240 (US National Library of Medicine Registry; https://www.clinicaltrials.gov/ct2/show/NCT02710240?id=NCT02710240&draw=2&rank=1 ).

Brain biopsy in suspected non-neoplastic neurological disease

Brain biopsy has a well-established role in the diagnosis of CNS neoplasia. Nevertheless, despite being essential for the diagnosis of some benign neurological diseases, little consensus exists regarding its indications for disease diagnosis and patient orientation. Our aim was to assess brain biopsy diagnostic yield in patients with neurological deterioration of unknown etiology, to identify the clinical characteristics associated with an increased likelihood of achieving a diagnostic biopsy as well as the characteristics linked to a particular diagnosis.

METHODS

A retrospective analysis of 62 consecutive brain biopsies performed at a single tertiary care center between January 2004 and December 2015 for suspected non-neoplastic neurological disease was performed. The clinical presentation, imaging, and laboratory results were collected and compared between diagnostic groups.

RESULTS

Sixty-eight percent of the biopsies led to a definitive diagnosis. The most common histological diagnosis was central nervous system lymphoma (eight cases), followed by astrocytoma, demyelinating disease, and progressive multifocal leukoencephalopathy (four cases each). No clinical characteristics were found to predict a diagnostic biopsy or to correlate with a specific diagnosis. Importantly, a distinct diagnosis from the initially suspected was achieved in 52% of cases and biopsy findings led to a change of therapeutic orientation in 78% of the cases.

CONCLUSIONS

Our results suggest that brain biopsies have a significant impact on patient management and should be considered early in selected cases in which less invasive testing was unable to reach a definitive diagnosis.

Molecular imaging of multiple sclerosis: from the clinical demand to novel radiotracers

BACKGROUND

Brain PET imaging with different tracers is mainly clinically used in the field of neurodegenerative diseases and brain tumors. In recent years, the potential usefulness of PET has also gained attention in the field of MS. In fact, MS is a complex disease and several processes can be selected as a target for PET imaging. The use of PET with several different tracers has been mainly evaluated in the research setting to investigate disease pathophysiology (i.e. phenotypes, monitoring of progression) or to explore its use a surrogate end-point in clinical trials.

RESULTS

We have reviewed PET imaging studies in MS in humans and animal models. Tracers have been grouped according to their pathophysiological targets (ie. tracers for myelin kinetic, neuroinflammation, and neurodegeneration). The emerging clinical indication for brain PET imaging in the differential diagnosis of suspected tumefactive demyelinated plaques as well as the clinical potential provided by PET images in view of the recent introduction of PET/MR technology are also addressed.

CONCLUSION

While several preclinical and fewer clinical studies have shown results, full-scale clinical development programs are needed to translate molecular imaging technologies into a clinical reality that could ideally fit into current precision medicine perspectives.

Value of 18F-FET PET in Patients With Suspected Tumefactive Demyelinating Disease-Preliminary Experience From a Retrospective Analysis

PURPOSE

To investigate the diagnostic value of F-fluoroethyl-L-tyrosine (FET) positron emission tomography (PET) in patients with suspected tumefactive demyelinating disease.

METHODS

We retrospectively examined FET-PET and MR imaging of 21 patients (12 female, 9 male) with known demyelinating disease and newly diagnosed tumefactive lesions. The maximum standardized uptake value (SUVmax), time activity curves (TAC) and lesion-to-background ratio (TBR) of these lesions were calculated. The standard of reference consisted of biopsy and/or follow-up imaging. FET parameters of true neoplastic lesions and tumefactive demyelinating lesions were compared using Mann-Whitney U-test and receiver operating characteristic (ROC) analysis.

RESULTS

Nine patients (42.9%) had neoplastic lesions, 12 patients (57.1%) had tumefactive demyelinating lesions. TBRmax, SUVmax and TAC were significantly different between demyelinating lesions and neoplastic lesions: Tumors had a higher TBRmax (3.53 ± 1.09 vs. 1.48 ± 0.31, respectively; P < 0.001) and SUVmax (3.95 ± 1.59 vs. 1.86 ± 0.50, respectively; P < 0.001) than tumefactive demyelinating lesions. The TAC of tumors was significantly higher compared to tumefactive demyelinating lesions at all time points (P < 0.05). ROC analysis revealed that a TBRmax threshold of 2.2 and a SUVmax threshold of 2.5 could reliably differentiate tumor and tumefactive demyelination (area under the curve, 1.000 and 0.958, respectively).

CONCLUSION

In patients with demyelinating disease, FET-PET parameters TBRmax (cut-off 2.2) and SUVmax (cut-off 2.5) are able to distinguish tumefactive demyelinations from true neoplastic lesions.

Transtentorial herniation from tumefactive multiple sclerosis mimicking primary brain tumor

Background

Multiple sclerosis (MS) is a chronic central nervous system inflammatory demyelinating disease characterized by multiple lesions disseminated in time and space. The lesions often have characteristic imaging findings on magnetic resonance (MR) imaging and cerebrospinal fluid findings that lead to their diagnosis. At times, these lesions may resemble tumors due to their large size (>2 cm), significant vasogenic edema, and ring-enhancing MR imaging findings. Such lesions are described as tumefactive demyelinating lesions or tumefactive MS, and they are generally seen in aggressive forms of MS associated with rapid progression.

Case Description

We report an uncommon but clinically significant case of transtentorial brain herniation secondary to malignant cerebral edema from tumefactive MS in a 50-year-old woman. After the initial diagnosis of MS, the patient continued to have progression of her white matter lesions suggesting evolution of her MS despite treatment with intravenous (IV) steroids, IV immunoglobulin, and plasmapheresis. She was admitted to the hospital with a new, large, ring-enhancing lesion that displayed significant mass effect from vasogenic edema and progressed, necessitating a decompressive hemicraniectomy.

Conclusion

Tumefactive MS presents a unique pathology that can often mimic primary brain tumors. Although these lesions affect white matter and infrequently cause a significant amount of mass effect, they can act like a tumor, causing edema that generates sufficient intracranial pressure to cause transtentorial herniation.

Contralateral recurrence of tumefactive demyelination

Tumefactive demyelination refers to large focal demyelinating lesions in the brain, which can be mistaken for malignancy. In some patients, these lesions are monophasic with a self-limited course; however, other patients demonstrate recurrent disease with new tumefactive or non-tumefactive lesions, and a subsequent diagnosis of relapsing-remitting multiple sclerosis is not uncommon. Owing to the limited data available in the literature, many questions about the patterns and prognostic significance of recurrent tumefactive lesions remain unanswered. The current case report involves a patient who recovered from tumefactive demyelination and presented two years later with a new recurrent tumefactive lesion in the contralateral brain.

Custom fit 3D-printed brain holders for comparison of histology with MRI in marmosets

BACKGROUND

MRI has the advantage of sampling large areas of tissue and locating areas of interest in 3D space in both living and ex vivo systems, whereas histology has the ability to examine thin slices of ex vivo tissue with high detail and specificity. Although both are valuable tools, it is currently difficult to make high-precision comparisons between MRI and histology due to large differences inherent to the techniques. A method combining the advantages would be an asset to understanding the pathological correlates of MRI.

NEW METHOD

3D-printed brain holders were used to maintain marmoset brains in the same orientation during acquisition of ex vivo MRI and pathologic cutting of the tissue.

RESULTS

The results of maintaining this same orientation show that sub-millimeter, discrete neuropathological features in marmoset brain consistently share size, shape, and location between histology and ex vivo MRI, which facilitates comparison with serial imaging acquired in vivo.

COMPARISON WITH EXISTING METHODS

Existing methods use computational approaches sensitive to data input in order to warp histologic images to match large-scale features on MRI, but the new method requires no warping of images, due to a preregistration accomplished in the technique, and is insensitive to data formatting and artifacts in both MRI and histology.

CONCLUSIONS

The simple method of using 3D-printed brain holders to match brain orientation during pathologic sectioning and MRI acquisition enables rapid and precise comparison of small features seen on MRI to their underlying histology.

Neuro-oncology dilemma: Tumour or tumefactive demyelinating lesion

Tumefactive demyelinating lesions (TDLs) are not an uncommon manifestation of demyelinating disease but can pose diagnostic challenges in patients without a pre-existing diagnosis of multiple sclerosis (MS) as well as in known MS patients. Brain tumours can also arise in MS patients and can be seen in chronic MS patients as co-morbidities. Delayed diagnosis or unnecessary intervention or treatment will affect the ultimate prognosis of these patients. In this article, we will review some typical cases illustrating the dilemma and review the information that helps to differentiate the two conditions. The intention is not to present an extensive differential diagnosis of both entities, but to examine some typical examples when the decision arises to decide between the two. We take a somewhat different approach, by presenting the cases in "real time", allowing the readers to consider in their own minds which diagnosis they favour, discussing in detail some of the pertinent literature, then revealing later the actual diagnosis. We would urge readers to consider re-visiting their first thoughts about each case after reading the discussion, before reading the follow-up of each case. The overall objective is to highlight the real possibility of being forced to decide between these two entities in clinical practise, present a reasonable approach to help differentiate them and especially to focus on the possibility of TDLs in order to avoid unnecessary biopsy.