Neuronavigated-biopsy in the diagniosis of demyelinating pseudotumoral brain lesions. Case report.

Abstract

Introduction: Pseudotumoral-demyelinating lesions are typically characterized by severe difficulties in differential diagnosis from gliomas, metastatic tumors and abscesses. Marburg’s disease (MD) is an extremely rare and aggressive form of Mutiple Sclerosis (MS) with acute onset, rapid neurological deterioration, and poor prognosis. MRI images often show pseudotumoral lesions characterized by mild and focal or, sometimes, ring enhancement. Perhaps, radiological aspect can vary, making necessary hystopathological confirmation. Objectives: There is increasing interest in the role of surgical biopsy for a correct and early diagnosis of pseudotumoral demyelinating lesions. We report an histopathologically confirmed case of MD. Thanks to the analysis of actual literature, our purpose is to ameliorate diagnostic criteria, the timing of treatment and, subsequently, the prognosis of patients affected. Matherials and methods: A 24 years-old woman presented with a sudden onset of motor subaphasia and numbness to the right hemiface, followed, in a few hours by rapid deterioration with mild pyramidal right hemiparesis and complete aphasia. Patient underwent to a CT brain examination which showed three unspecific hypodense lesions: the bigger one, in the left subcortical frontal white matter, and two smaller lesions in the deep parietal and in the right paratrigonal white matter. For better characterization, a brain MRI was performed. The lesions in the right paratrigonal and left parietal white matter where appreciable as highly hyper-intense on TSE-T2 and FLAIR-T2 sequences, hypo-intense on TSE-T1, and responsible for a moderate mass effect on the surrounding structures; the left parietal white matter lesion also showed an incomplete and irregular ring-enhancement. The left subcortical frontal lesion was only mild hyper-intense on TSE-T2 and FLAIR-T2 but strongly hyper-intense on DWI, and a subsequent MRI scan showed a pseudotumoral development with an atypical patchy enhancement. Total body CT scan, auto-antibodies and viral serology on blood and CSF were negative. Isoelectric focusing in agarose gel detected the presence of CSF oligoclonal bands. Steroids were administrated without significant improvement. On the basis of the obtained data, and in consideration of the poor responsiveness to steroids, we performed a neuronavigator-aided biopsy of the main lesion through an open microsurgical approach. Preoperative planning was performed the day before by using contrast agent-enhanced brain CT scan, after positioning markers on the scalp. The exam was then transferred on a data storage device to insert CT images on the neuronavigator. The principal landmarks were used to realize a temporal craniotomy and a small corticectomy centred on the lesion. Finally, we detected, at a depth of about 2 cm, a pathological curdy and whitish tissue, ablated in small fragments and sent for hystological examination. A post-operative CT scan excluded any complications and the patient had a regular course. At demission, neurological exam was slightly better with partial regression of hemiparesis and partial amelioration of speech function. Hystopathological report confirmed the hypothesis of Marburg’s variant of MS. Results and Conclusions: Initial therapeutic approach to MS is pharmacological. However, in some atypical cases, CSF analisys, MRI images and/or clinical course after sterioids administration are not sufficiently diagnostic to completely rule out tumors or abscesses. So, early biopsy is an unavoidable necessity for the differential diagnosis of pseudotumoral-demyelinating lesions, to prevent inappropriate surgical or irradiative treatments and ameliorate the prognosis.