Methionine-PET to differentiate between brain lesions appearing similar on conventional CT/MRI scans

BACKGROUND AND PURPOSE

11 C-Methionine (MET)-PET is a useful tool in neuro-oncology. This study aimed to examine whether a combination of diagnostic variables associated with MET uptake could help distinguish between brain lesions that are often difficult to discriminate in conventional CT and MRI.

METHODS

MET-PET was assessed in 129 patients with glioblastoma multiforme, primary central nervous lymphoma, metastatic brain tumor, tumefactive multiple sclerosis, or radiation necrosis. The accuracy of the differential diagnosis was analyzed using five diagnostic characteristics in combination: higher maximum standardized uptake value (SUV) of MET in the lesion/the mean normal cortical SUV of MET ratio, overextension beyond gadolinium, peripheral pattern indicating abundant MET accumulation in the peripheral region, central pattern denoting abundant MET accumulation in the central region, and dynamic-up suggesting increased MET accumulation during dynamic study. The analysis was conducted on sets of two of the five brain lesions.

RESULTS

Significant differences in the five diagnostic traits were observed among the five brain lesions, and differential diagnosis could be achieved by combining these diagnostic features. The area under the curve between each set of two of the five brain lesions using MET-PET features ranged from .85 to 1.0.

CONCLUSIONS

According to the findings, combining the five diagnostic criteria could help with the differential diagnosis of the five brain lesions. MET-PET is an auxiliary diagnostic technique that could help in distinguishing these five brain lesions.

Specific myeloid signatures in peripheral blood differentiate active and rare clinical phenotypes of multiple sclerosis

Current understanding of Multiple Sclerosis (MS) pathophysiology implicates perturbations in adaptive cellular immune responses, predominantly T cells, in Relapsing-Remitting forms (RRMS). Nevertheless, from a clinical perspective MS is a heterogeneous disease reflecting the heterogeneity of involved biological systems. This complexity requires advanced analysis tools at the single-cell level to discover biomarkers for better patient-group stratification. We designed a novel 44-parameter mass cytometry panel to interrogate predominantly the role of effector and regulatory subpopulations of peripheral blood myeloid subsets along with B and T-cells (excluding granulocytes) in MS, assessing three different patient cohorts: RRMS, PPMS (Primary Progressive) and Tumefactive MS patients (TMS) (n=10, 8, 14 respectively). We further subgrouped our cohort into inactive or active disease stages to capture the early underlying events in disease pathophysiology. Peripheral blood analysis showed that TMS cases belonged to the spectrum of RRMS, whereas PPMS cases displayed different features. In particular, TMS patients during a relapse stage were characterized by a specific subset of CD11c+CD14+ CD33+, CD192+, CD172+-myeloid cells with an alternative phenotype of monocyte-derived macrophages (high arginase-1, CD38, HLA-DR-low and endogenous TNF-a production). Moreover, TMS patients in relapse displayed a selective CD4 T-cell lymphopenia of cells with a Th2-like polarised phenotype. PPMS patients did not display substantial differences from healthy controls, apart from a trend toward higher expansion of NK cell subsets. Importantly, we found that myeloid cell populations are reshaped under effective disease-modifying therapy predominantly with glatiramer acetate and to a lesser extent with anti-CD20, suggesting that the identified cell signature represents a specific therapeutic target in TMS. The expanded myeloid signature in TMS patients was also confirmed by flow cytometry. Serum neurofilament light-chain levels confirmed the correlation of this myeloid cell signature with indices of axonal injury. More in-depth analysis of myeloid subsets revealed an increase of a subset of highly cytolytic and terminally differentiated NK cells in PPMS patients with leptomeningeal enhancement (active-PPMS), compared to those without (inactive-PPMS). We have identified previously uncharacterized subsets of circulating myeloid cells and shown them to correlate with distinct disease forms of MS as well as with specific disease states (relapse/remission).

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.

[Difficulties of cerebral toxoplasmosis diagnosis in a patient with multiple sclerosis and HIV]

Toxoplasmosis is a widespread parasitic disease. It is caused by an intracellular parasite Toxoplasma gondii. It can affect various tissues and organs, forming cysts and continuing to replicate within them. In people with intact immune system, tissue cysts remain in latent state throughout their whole life. However, in cases of cellular immunodeficiency the infection can be reactivated, which leads to secondary generalization of the process. People with HIV most commonly present with cerebral toxoplasmosis. Non-specific neuroimaging signs, as well as absence of pathognomonic symptoms and specific laboratory data lead to difficulties of cerebral toxoplasmosis diagnosis, particularly in the cases with a history of multiple sclerosis that has similar clinical symptoms and brain MRI data suggesting of tumefactive multiple sclerosis image. A clinical case of cerebral toxoplasmosis in a female patient with multiple sclerosis and HIV infection is described.

Case Report: A Case of Severe Clinical Deterioration in a Patient With Multiple Sclerosis

Tumefactive multiple sclerosis (MS) is a rare variant of MS that may lead to a rapidly progressive clinical deterioration requiring a multidisciplinary diagnostic workup. Our report describes the diagnostic and therapeutic approach of a rare and extremely severe course of MS. A 51-year-old man with an 8-year history of relapsing-remitting MS (RRMS) was admitted with a subacute progressive left lower limb weakness and deterioration of walking ability. After extensive investigations including repeated MRI, microbiological, serological, cerebrospinal fluid (CSF) studies, and finally brain biopsy, the diagnosis of a tumefactive MS lesion was confirmed. Despite repeated intravenous (IV) steroids as well as plasma exchanges and IV foscarnet and ganciclovir owing to low copy numbers of human herpesvirus 6 (HHV-6) DNA in polymerase chain reaction (PCR) analysis, the patient did not recover. The clinical presentation of tumefactive MS is rare and variable. Brain biopsy for histopathological workup should be considered in immunocompromised patients with rapidly progressive clinical deterioration with brain lesions of uncertain cause.

Recurrent Fulminant Tumefactive Demyelination With Marburg-Like Features and Atypical Presentation: Therapeutic Dilemmas and Review of Literature

Atypical forms of demyelinating diseases with tumor-like lesions and aggressive course represent a diagnostic and therapeutic challenge for neurologists. Herein, we describe a 50-year-old woman presenting with subacute onset of left hemiparesis, memory difficulties and headache. Brain MRI revealed a tumefactive right frontal-parietal lesion with perilesional edema, mass effect and homogenous post-contrast enhancement, along with other small atypical lesions in the white-matter. Brain biopsy of cerebral lesion ruled out lymphoma or any other neoplastic process and patient placed on corticosteroids with complete clinical/radiological remission. Two years after disease initiation, there was disease exacerbation with reappearance of the tumor-like mass. The patient initially responded to high doses of corticosteroids but soon became resistant. Plasma-exchange sessions were not able to limit disease burden. Resistance to therapeutic efforts led to a second biopsy that showed perivascular demyelination, predominantly consisting of macrophages, with a small number of T and B lymphocytes, and the presence of reactive astrocytes, typical of Creutzfeldt-Peters cells. The patient received high doses of cyclophosphamide with substantial clinical/radiological response but relapsed after 7-intensive cycles. She received 4-weekly doses of rituximab with disease exacerbation and brainstem involvement. She eventually died with complicated pneumonia. We present a very rare case of recurrent tumefactive demyelinating lesions, with atypical tumor-like characteristics, with initial response to corticosteroids and cyclophosphamide, but subsequent development of drug-resistance and unexpected exacerbation upon rituximab administration. Our clinical case raises therapeutic dilemmas and points to the need for immediate and appropriate immunosuppression in difficult to treat tumefactive CNS lesions with Marburg-like features.

Usefulness of [11C] Methionine PET in the Differentiation of Tumefactive Multiple Sclerosis from High Grade Astrocytoma

Tumefactive multiple sclerosis (tumefactive MS) is an atypical variant of MS characterized by a large isolated demyelinating lesion. Because tumefactive MS mimics high grade astrocytoma clinically and radiologically, it is difficult to distinguish between the two using only traditional diagnostic modalities, such as routine magnetic resonance imaging. [¹¹C] methionine positron emission tomography (MET PET) has been known as a useful diagnostic tool for glioma. However, it has not been established as a diagnostic tool for tumefactive MS yet. Therefore, the objective of this study was to evaluate the performance of MET PET in differentiating tumefactive MS from high grade astrocytoma. We studied patients with tumefactive MS [six patients (three men, three women), 7 lesions] and 77 patients with astrocytoma (World Health Organization grade II: 13 patients, grade III: 28 patients, and grade IV: 36 patients), and we compared MET uptake of tumefactive demyelinating lesions and astrocytoma. For MET PET analysis, Lesion/Normal region ratios (L/N ratios) were calculated and compared between tumefactive demyelinating lesions and astrocytoma. On MET PET, the L mean/N ratio of tumefactive MS was 1.18 ± 0.50, which was significantly lower than that of high-grade glioma (astrocytoma grade III: 1.95 ± 0.62, P = 0.006; grade IV: 2.35 ± 0.54, P <0.0001). The L maximum (L max)/N ratio of tumefactive demyelinating lesion was also significantly lower than that of high grade astrocytoma (tumefactive MS: 1.89 ± 0.55; astrocytoma grade III: 3.37 ± 1.36, P = 0.0232; astrocytoma grade IV: 4.35 ± 1.30, P <0.0001). In conclusion, MET PET can help differentiate tumefactive MS from high grade astrocytoma.

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.

A challenging diagnosis of late-onset tumefactive multiple sclerosis associated to cervicodorsal syringomyelia: doubtful CT, MRI, and bioptic findings: Case report and literature review

BACKGROUND

Tumefactive multiple sclerosis (MS) is an unusual variant of demyelinating disease characterized by lesions with pseudotumoral appearance on radiological imaging mimicking other space-occupying lesions, such as neoplasms, infections, and infarction. Especially when the patient's medical history is incompatible with MS, the differential diagnosis between these lesions constitutes a diagnostic challenge often requiring histological investigation. An older age at onset makes distinguishing tumefactive demyelinating lesion (TDL) from tumors even more challenging.

METHODS

We report a case of brain TDL as the initial manifestation of late-onset MS associated with cervico-dorsal syringomyelia. A 66-year-old Caucasian woman with a 15-day history headache was referred to our hospital because of the acute onset of paraphasia. She suffered from noncommunicating syringomyelia associated to basilar impression and she reported a 10-year history of burning dysesthesia of the left side of the chest extended to the internipple line level.

RESULTS

Computed tomography (CT) and magnetic resonance imaging (MRI) examinations revealed a left frontal lesion with features suspicious for a tumor. Given the degree of overlap with other pathologic processes, CT and MRI findings failed to provide an unambiguous diagnosis; furthermore, because of the negative cerebrospinal fluid analysis for oligoclonal bands, the absence of other lesions, and the heightened suspicion of neoplasia, the clinicians opted to perform a stereotactic biopsy. Brain specimen analysis did not exclude the possibility of perilesional reactive gliosis and the patient, receiving anitiedemigen therapy, was monthly followed up. In the meanwhile, the second histological opinion of the brain specimen described the absence of pleomorphic glial cells indicating a tumor. These findings were interpreted as destructive inflammatory demyelinating disease and according to the evolution of MRI lesion burden, MS was diagnosed.

CONCLUSION

TDL still remains a problematic entity clinically, radiologically, and sometimes even pathologically. A staged follow-up is necessary, and in our case, it revealed to be the most important attitude to define the nature of the lesion, confirming the classic MS diagnostic criteria of disseminate lesions in time and space. We discuss our findings according to the recent literature.

Neuromyelitis Optica Spectrum Disorder with Tumefactive Demyelination mimicking Multiple Sclerosis: A Rare Case

Neuromyelitis optica spectrum disorder (NMOSD) is a diverse condition which not only encompasses isolated longitudinally extensive transverse myelitis (LETM) and optic neuritis but also includes area postrema syndrome, acute brainstem syndrome, symptomatic narcolepsy or acute diencephalic clinical syndrome, and symptomatic cerebral syndrome. Imaging may reveal periependymal lesions surrounding the ventricular system or involvement of corticospinal tracts, area postrema, diencephalon, and corpus callosum. Rarely, there may be hemispheric tumefactive lesions that enhance in a "Cloud-like" fashion on gadolinium injection unlike in tumefactive multiple sclerosis where there is incomplete ring enhancement. Here, we present a case of aquaporin-4 positive relapsing NMOSD who presented to us with recurrent episodes of paraparesis with LETM and tumefactive lesions of brain on imaging, which enhanced in an incomplete ring like pattern resembling multiple sclerosis.

18F-fluoroethyl-L-tyrosine positron emission tomography for the differential diagnosis of tumefactive multiple sclerosis versus glioma: A case report

Large demyelinating inflammatory central nervous system (CNS) lesions may present with contrast enhancement on magnetic resonance imaging and may mimic CNS tumors such as glioma. In ambiguous cases, new diagnostic tools that may be helpful for distinguishing between demyelinating inflammatory and neoplastic CNS lesions are required. The current study presents the case of a patient with a large contrast-enhanced frontal brain lesion, who was initially diagnosed with tumefactive multiple sclerosis. Following the progression of the brain lesion, an ¹⁸F-fluoroethyl-L-tyrosine positron emission tomography (¹⁸F-FET PET) was performed, revealing markedly elevated static ¹⁸F-FET uptake parameters along with time activity-curves consistent with glioma. Subsequently, a biopsy was undertaken, which confirmed the presence of anaplastic oligoastrocytoma. This case illustrates that ¹⁸F-FET PET may provide useful diagnostic information in cases where distinction between neoplastic and demyelinating inflammatory CNS lesions is challenging. However, further systematic and prospective analyses are warranted to explore the value of this method in this setting.

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.