A novel radiological appearance of meningeal extranodal marginal-zone B-cell lymphoma

Abstract

Neurological examination revealed left arm and leg weakness of 2e3/5, with no other significant findings, and computed tomography (CT) was performed to confirm a clinical diagnosis of right hemisphere infarct. Pre and post-contrast enhanced CT examinations of the head demonstrated patchy periventricular low-attenuation changes consistent with small-vessel disease that were not felt to be responsible for the new neurological symptoms, and also an area of non-enhancing gyral swelling in the right parietal lobe (Fig. 1). In view of the clinical presentation, a diagnosis of subacute infarct was considered, but the appearances were atypical and differential radiological diagnoses of low-grade neoplasm and focal encephalitis were also made. In view of the radiological uncertainty, magnetic resonance imaging (MRI) was performed. This showed an area of apparent gyral swelling confined to the right parietal lobe, without signal change in the cortex or underlying white matter. There was no evidence of haemorrhage or of altered diffusivity and no enhancement after gadolinium administration (Fig. 2). At this stage the radiological appearances were felt to be atypical of an infarct, but the clinical condition of the patient improved and an interval MRI examination was planned. However, during this interval the patient became more unwell with increasing leftsided weakness and headaches. The headaches were occipital, at their worst in the mornings, but not associated with nausea or vomiting. There was no papilloedema on fundoscopic examination. Interval MRI examinations did not reveal any change in the appearances of the right parietal abnormality. After a sudden deterioration the patient was admitted to the neurosurgical unit bed-bound with severe left hemiparesis, and having had a transient episode of aphasia. Further imaging revealed no change, and a probable diagnosis of low-grade astrocytoma was made. After discussion at the regional neuro-oncology multi-disciplinary meeting, the decision was made not to treat empirically. The neuropathologist requested that the surgeon include some meningeal tissue in the biopsy as it may be helpful in ascertaining a histological diagnosis. Subsequently surgical biopsy of the right parietal lobe and overlying meninges was performed.