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Published on: September 25, 2019
Pathologic and MRI analysis in acute atypical inflammatory demyelinating lesions
Xavier Ayrignac1,2, Valérie Rigau3, Benoit Lhermitte4
1Department of Neurology, Multiple Sclerosis Center, Montpellier University Hospital, 80 rue Augustin Fliche, 34295, Montpellier, Cedex 05, France. xavier.ayrignac@yahoo.fr.
Background:
The diagnosis of atypical inflammatory demyelinating lesions can be difficult. Brain biopsy is often required to exclude neoplasms. Moreover, the relationship between these lesions and multiple sclerosis and NMOSD is not clear.
Objectives:
Our objectives were to describe radiological and pathological characteristics of patients with acute inflammatory demyelinating lesions.
Methods:
We retrospectively identified patients with brain biopsy performed for diagnostic uncertainty revealing a demyelinating lesion. A complete clinical, biological, radiological and pathological analysis was performed.
Results:
Twenty patients (15 with a single lesion) were included. MRI disclosed a wide range of lesions including infiltrative lesions (40%), ring-like lesion (15%) Baló-like lesion (15%) and acute haemorrhagic leukoencephalitis (20%). In spite of a marked heterogeneity, some findings were common: a peripheral B1000 hyperintense rim (70%), a slight oedema with mild mass effect (75%) and an open-rim peripheral enhancement (75%). Histopathology revealed that all cases featured macrophages distributed throughout, extensive demyelination, axonal preservation and absence of haemorrhagic changes. In the majority of cases, macrophages were the predominant inflammatory infiltrate and astrocytes were reactive and dystrophic. Aquaporin-4 staining was systematically preserved. After a mean follow-up of 5 years (1-12), 16/20 patients had a diagnosis of monophasic acute atypical inflammatory demyelinating lesion. One patient was diagnosed with MS and 3 with AQP4 negative NMOSD.
Discussion:
Although imaging findings in patients with atypical inflammatory demyelinating lesions are heterogeneous, some common features such as peripheral DWI hyperintense rim with open-rim enhancement and absence of oedema argue in favour of a demyelinating lesion and should preclude a brain biopsy. In this context, AQP4 staining is systematically preserved and argues against an AQP4-positive NMOSD. Moreover, long-term follow-up is characterized by low recurrence rate.
Insights
Diagnosing atypical inflammatory demyelinating lesions can be challenging. Common MRI findings like peripheral DWI hyperintense rim and open-rim enhancement suggest demyelination, potentially avoiding brain biopsy.
Area of Science:
- Neurology
- Neuroimaging
- Pathology
Background:
- Atypical inflammatory demyelinating lesions pose diagnostic challenges, often necessitating brain biopsy to rule out neoplasms.
- The precise relationship between these lesions and conditions like multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) remains unclear.
Purpose of the Study:
- To delineate the radiological and pathological features of patients presenting with acute inflammatory demyelinating lesions.
- To identify common diagnostic characteristics that may help differentiate these lesions from other neurological conditions.
Main Methods:
- Retrospective analysis of patients who underwent brain biopsy for diagnostic uncertainty, revealing demyelinating lesions.
- Comprehensive clinical, biological, radiological, and pathological evaluation of included patients.
Main Results:
- Twenty patients were analyzed, exhibiting diverse MRI findings including infiltrative, ring-like, Baló-like lesions, and acute hemorrhagic leukoencephalitis.
- Consistent features included a peripheral B1000 hyperintense rim (70%), mild edema with mass effect (75%), and open-rim peripheral enhancement (75%).
- Histopathology showed macrophages, extensive demyelination, preserved axons, and preserved Aquaporin-4 (AQP4) staining. AQP4 staining was preserved in all cases, arguing against AQP4-positive NMOSD.
Conclusions:
- Heterogeneous imaging findings in atypical inflammatory demyelinating lesions are common, but specific features like peripheral DWI hyperintense rim and open-rim enhancement suggest demyelination and may obviate the need for brain biopsy.
- Preserved AQP4 staining is a key indicator against AQP4-positive NMOSD.
- Long-term follow-up reveals a low recurrence rate for these lesions, with most patients diagnosed with monophasic lesions rather than MS or NMOSD.
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