PITFALLS IN DIAGNOSIS OF PSEUDOTUMORS OF THE CENTRAL NERVOUS SYSTEM--A TUMEFACTIVE MULTIPLE SCLEROSIS LESION MIMICKING A GLIOBLASTOMA

Background: Pseudotumors of the central nervous system are rare lesions. Patients often present symptoms suggesting a space-occupying tumor or an ischemia. On imaging they can mimic a broad range of underlying diseases like ischemia, tumor lesions, inflammatory and demyelinating ailments. We intend to highlight such a case and the redundant pitfalls in the diagnosis of such cases. Methods: Case report about a 34y old female patient that was hospitalized under the suspicion of having a stroke. Result: All radiological criteria of the initial cCT and cMRI (Sequences: T2, T1-/+ contrast, FLAIR, DWI, ADC, TOF) strengthened the diagnosis of a fresh ischemia of the right frontoparietal region. In combination with results from a liquoranalysis the stroke was deemed post-infectious. Because of a clinical deterioration a follow-up MRI was conducted 6 weeks later. What had previously been described as an ischemic area now showed the characteristics of a tumorous lesion with signs of malignancy. Furthermore a new lesion was found in the frontal region which was then biopsied. The lesion showed areas of demyelination. Consequently the diagnosis was Multiple Sclerosis (MS). After a cortisone treatment the clinical symptoms decreased and there was an improvement of the radiological findings. A maintenance therapy with Interferon-[beta] followed. Discussion: In some cases MS-lesions can mimic radiographic and histologically neoplasia like high-grade gliomas. The lesions can show a rapid enlargement, a surrounding edema and a marginal contrast-enhancement. Such lesions lead to the term: Tumefactive multiple sclerosis (1). A special entity of such tumor-like MS-lesions is the concentric sclerosis balo (2). The pathologically and radiologically criterias are concentric rings of demyelination and myelin-preserved regions of the white matter with a corresponding concentric contrast-enhancement. The parietal lesion, found in this case, showed such radiographic criteria. Conclusion: The initial diagnosis and also the subsequent management of a Pseudotumor, as shown in this case, can be difficult.