CASE 15617 Published on 23.04.2018

Tumefactive demyelinating lesion

Section

Neuroradiology

Case Type

Clinical Cases

Authors

Klemen Mihelčič, Jernej Avsenik

Clinical Institute of Radiology,
University Medical Centre Ljubljana;
Zaloska cesta 7,
1000 Ljubljana, Slovenia
Patient

45 years, male

Categories
Area of Interest Neuroradiology brain ; Imaging Technique MR, MR-Spectroscopy
Clinical History
45-year-old man with 7 year history of dysarthria presented in 2018 with clinical worsening. Past MRI showed multiple brain lesions, biopsy showed no tumour cells but was otherwise inconclusive. LP was negative for oligoclonal bands. The patient was diagnosed with status post ADEM. There was moderate improvement after corticosteroids.
Imaging Findings
MRI from 2015 showed small T2/FLAIR hyperintense lesion in the left frontal white matter (Fig. 1). No post-contrast enhancement was seen. Small area of atrophy with surrounding gliosis after biopsy was present on the right.
MRI in 2018 (Fig. 2) showed enlargement of the previously described lesion in the left frontal lobe and newly developed round lesion in the right upper frontal gyrus. Both lesions were clearly hypointense on T1, hyperintense on T2 / FLAIR imaging and were surrounded by marked focal oedema. Intense post-contrast open ring enhancement was present as well, best seen on coronal and sagittal reformations (Fig. 3).
MR spectroscopy in the right frontal lobe lesion showed elevated choline, low N-acetyl aspartate and pathological lactate-lipid peak (Fig. 4).
DSC MRI showed low rCBV in the centre of the lesions (Fig. 5).
DWI showed low diffusion peripherally and high ADC values centrally as well as in the perilesional oedema (Fig. 6).
Discussion
Background
Tumefactive demyelinating lesions (TDL) are a rare disease of the central nervous system (CNS). TDLs are most commonly observed in the context of multiple sclerosis (MS). Other primary demyelinating diseases such as acute disseminated encephalomyelitis (ADEM) and acute haemorrhagic leukoencephalitis can also manifest as TDL. It remains unclear whether TDLs represent a variant of MS or a demyelinating disease on its own [1, 2].
The prevalence of TDL is estimated to be 1–3/1000 cases of MS with an annual incidence of 0.3 per 100000. They may occur at any age but are most prevalent between 20-40 years of age [1].

Clinical Perspective
Clinical presentation is often atypical for a demyelinating disease and usually polysymptomatic. Motor, sensory, cognitive and cerebellar symptoms are predominant and they may develop over days or weeks. TDLs are often supratentorial with the most common symptoms being memory dysfunction (17%), aphasia (17%), apraxia (4%), Gerstmann syndrome (4%), seizures, impaired consciousness and visual field deficits [2, 3].

Imaging Perspective
Diagnosis of TDL is not always straightforward since the clinical and radiological findings can mimic other lesions such as brain tumour. MRI is the gold standard imaging modality for TDL diagnosis, including gadolinium enhanced images. TDLs are mainly localised in the subcortical hemispheric white matter but may also be found in the corpus callosum. Most are focal and supratentorial with a tendency towards the frontal and parietal lobes [3-5]. MRI features consist of: size of more than 2 cm, incomplete ring enhancement (as compared to the complete ring of enhancement seen in abscesses and tumours) and large number of lesions [2-5]. High apparent diffusion coefficient (ADC) values are typical, however, low diffusion has been observed in active demyelinating lesions.
Perfusion images may aid in the differentiation of TDL from brain tumours by measuring the mean relative cerebral blood volume within the TDL which will be significantly less than in the brain tumours. However, perfusion imaging may not be conclusive in the cases of glioblastoma multiforme (GBM) and primary CNS lymphoma for example. To differentiate between primary CNS lymphoma and TDL, magnetic resonance spectroscopy (MRS) and CSF analysis may be useful. MRS of TDLs could show an increased choline and/or lactate peaks although these are not specific and may be observed in neoplasms as well [6].
Differential Diagnosis List
Tumefactive demyelinating lesion
CNS neoplasm
Brain metastasis
Brain abscess
Granulomatous disease
Vasculitis
ADEM
Final Diagnosis
Tumefactive demyelinating lesion
Case information
URL: https://eurorad.org/case/15617
DOI: 10.1594/EURORAD/CASE.15617
ISSN: 1563-4086
License